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Power transmission harmonic current and its use in geophysical exploration McCollor, Douglas Clayton 1982

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c.  POWER AND  ITS  TRANSMISSION USE IN  HARMONIC  GEOPHYSICAL  CURRENT  EXPLORATION  by  DOUGLAS B . S c ,  A  The  THESIS THE  CLAYTON M COLLOR c  University  SUBMITTED  of  IN  PARTIAL  REQUIREMENTS MASTER  B r i t i s h  Columbia,  FULFILLMENT OF  FOR THE DEGREE OF OF  SCIENCE  in THE  FACULTY OF GRADUATE  (Department  We  accept to  THE  of  Geophysics  this  the  UNIVERSITY  Douglas  Clayton  Astronomy)  conforming  standard  OF BRITISH  March  ©  as  required  STUDIES  and  thesis  COLUMBIA  1982  M Collor, c  1979  1982  In p r e s e n t i n g  t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of  requirements f o r an advanced degree a t the  the  University  o f B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make it  f r e e l y a v a i l a b l e f o r reference  and  study.  I  further  agree t h a t p e r m i s s i o n f o r e x t e n s i v e copying o f t h i s t h e s i s f o r s c h o l a r l y purposes may department or by h i s or her  be granted by the head o f representatives.  my  It is  understood t h a t copying or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l gain  s h a l l not be allowed without my  permission.  Department o f  G)lffllwft€l$ '  f  u  4^J^ ^^ ) ; '  The U n i v e r s i t y of B r i t i s h Columbia 1956 Main Mall Van couve r , Canada V6T 1Y3 Date  DE-6  (.3/81)  >  U  written  i i  ABSTRACT  Commercial as  an  electrical  economical  exploration.  The  source  aspect  of  signal  that  line.  The  extraneous proposed which  isolated  region  West  from  sources  power  500  KV  of  well  this  proposed  method the  Meridian  substation,  correspondence  relation  given,  as  harmonic An situated  to  well  line  near  was  B.C.  current  natural  B.C.  GIC  and  illustrative  A  be  isolated  built  the  area  (near  from  was  yielded In  field  current  an  i n an  East-  made  was the to  through  quantitative addition,  the  activity  and  in  discussion  current the  of  Access  (GIC)  theoretical  showing  through begins.  exploration.  and  in  viability  current  the  areas,  Vancouver)  the  harmonic  data  remote  transmission  extending  geomagnetic  determined.  between  of  strength.  induced  the  developing  line  harmonic  the  s i g n a l s . However,  determine  loco,  in  i s commonly  electromagnetic  between  as  loco,  to  harmonic  line  line  used  multi-frequency  must  Hz  urbanization  geomagnetically  transmission the  for  suitable  transmission  transmission  on  area  be  thesis  monitor  the  60  Nicola  of  current  be  geophysical  include  strong,  commercial  before  Hydro  from  in  information  existing  can  of  technique the  i s that  lines  method  the  plus  transmission  utilized  quasi-DC  the  would  B.C.  direction  of  method,  limitation  a  A  the  technique  transmission  reconnaissance  advantages  arises  main  power  generation  effect  of  GIC  the of is on  currents. extensive to  the  EM  north  survey of  the  was  undertaken  Nicola-loco  i n an  isolated  transmission  region  line.  The  magnitude  of  four source measured  the  frequencies  at  66  survey  the v e r t i c a l  relation as  (60 Hz,  1/r  this  3  with  ambient f i e l d  field Hz,  km  a r e a . The  2  aspect  theoretical  data  calculations  addition, different features  of  the  source  supports  on  and  by  the  practicable  contrasts,  and  reconnaisance  results  of  this  an  terms  inverse  to f a l l  off  the  distance  of  frequency model,  and  half-  and  some  the t r a n s i t i o n d i s t a n c e are  data,  to  given.  correlate  indicating conductivity contrasts  regions.  r e s u l t s presented technique  for  could  a  be  was  begins  Thus t h e p r o p o s e d method o f e l e c t r o m a g n e t i c shown,  Hz)  of t h e model i s  g e o l o g i c r e g i o n s were f o u n d  a s s o c i a t e d w i t h the g e o l o g i c  420  exhibits  s o u r c e , and  d e p e n d a n t on  and  interpreted in  a t g r e a t e r d i s t a n c e s from the s o u r c e , being  component, at  300  component  d i s t a n c e near the  transition  with  Hz,  e a r t h m o d e l . One  s p a c e c o n d u c t i v i t y . The  In  180  were q u a l i t a t i v e l y  a uniform conducting  that  v e r t i c a l magnetic  s t a t i o n s w i t h i n a 120  the experimental of  total  exploration for  exploration  in this thesis, mapping  geologic  t o be a  is  viable  conductivity  s u c c e s s f u l , i n e x p e n s i v e method of orebodies.  iv  Table  of  Contents Page  Abstract  i i  List  of T a b l e s  List  of F i g u r e s  v  Acknowledgments  Chapter  I:  i  Introduction  C h a p t e r I I : Power 2.1 G e n e r a l 2.2 H a r m o n i c s  i  v  Systems  x  1 6 6 8  Chapter I I I : Experimental Procedure 3.1 E x p e r i m e n t a l O b j e c t i v e s 3.2 I n s t r u m e n t a t i o n 3.3 C a l i b r a t i o n P r o c e d u r e  17 17 22 25  C h a p t e r IV: Experimental Results 4.1 GIC's d e t e c t e d i n 5L82 a t M e r i d i a n S u b s t a t i o n 4.2 H a r m o n i c C u r r e n t M e a s u r e m e n t s i n M e r i d i a n 4.3 E f f e c t s of GIC on H a r m o n i c C u r r e n t s  29 29 30 34  Chapter 5.1 5.2 5.3 5.4  48 48 49 60 61  V: EM S u r v e y : E x p e r i m e n t and R e s u l t s I n t r o d u c t i o n t o EM E x p e r i m e n t P r e l i m i n a r y Experiment and Apparatus R e s u l t s of t h e 1981 S u r v e y A n a l y s i s and I n t e r p r e t a t i o n  Chapter  VI:  Conclusion  References  82  90  Appendix  A:  Harmonic A n a l y s i s  Appendix Appendix  B: C:  I n s t r u m e n t a t i o n and C a l i b r a t i o n EM-Survey D a t a A n a l y s i s  93 96 113  V  List  of  Tables Page  Table  2.1  Phase  Table  4.1  Maximum H a r m o n i c C u r r e n t Measurements at Meridian Substation  Table  6.1  Sequence C u r r e n t s  11 on 5L82  D e t e r m i n i n g 6 / c (minimum d i s t a n c e from l i n e s o u r c e f o r w h i c h ay>6 and y>>h), w h i c h corresponds to a t o t a l f i e l d - distance r e l a t i o n of 1 / r  85  Magnetic F i e l d Strengths (15:50 L T , 2 2 / 7 / 8 1 )  88  3  Table  6.2  .32  at  base  station  vi  L i s t  of  Figures  Page  F i g .  2.1  A  generator  and  F i g .  2.2  a  connected  high  voltage  through  line  to  a  transformers distant  load  7  A three-phase transformer bank, the disconnect switches, and a three-phase c i r c u i t breaker connecting to a three-phase transmission line  F i g .  2.3  A  three-phase  F i g .  2.4  Two  F i g .  2.5  Three-phase  common  system  7  ,  three-phase  impedance  transformer  system  connections  2.6  Diagram  F i g .  2.7  GIC  in  of  10  an  idealized  (geomagnetically  ground  of  AC machine  induced  transformer  flowing  bank  F i g .  3.2  Topographical  F i g .  3.3  Schematic  F i g .  3.4  Harmonic  F i g .  4.1  Effect  geomagnetic  f i e l d  on  GIC  in  5L82  4.2  (3 M a r c h 1981) Effect of geomagnetic (4 A p r i l 1981)  f i e l d  on  GIC  in  5L82  of  survey  representation  current  and  for  14  Location  map  area  current)  3.1  F i g .  survey  10  F i g .  of  of  9  in  Y-connection  F i g .  9  of  EM f i e l d  work  18  area  20  apparatus  23  GIC c a l i b r a t i o n  c i r c u i t s  . . . . 2 7  36 37  vii  Page Fig.  4.3  Harmonic c u r r e n t  levels  (3 M a r c h 1981)  Fig.  4.4  Harmonic c u r r e n t (1 1 J u n e 1981 )  levels  and geomagnetic  Fig.  Fig.  Fig.  Fig.  Fig.  4.5  5.1  5.2  5.3  5.4  Correspondence calibration  38 field 42  of  relative  v a l u e s and  current 47  L o c a t i o n of m o b i l e r e c e i v e r survey area  stations  within 51  R e s u l t s o f t h r e e s u r v e y s ( 1 9 7 9 , 8 0 , 81) t o show 1/r d e p e n d a n c e o f t o t a l f i e l d s t r e n g t h AF-measurements at base (3 M a r c h 1981)  station  AF-measurements at base  station  (11 J u n e  ......52  55  1981)  57  Fig.  5.5  EM s u r v e y c o n t o u r e d  Fig.  5.6  Reference  Fig.  5.7  Profile  Fig.  5.8  P r o f i l e data -  Section A-B  73  Fig.  5.9  P r o f i l e data -  S e c t i o n C-D  75  Fig.  5.10  Geologic  map of  Fig.  5.11  Geologic  cross-section  6.1  Lake r e g i o n V e r t i c a l Induced  Fig.  data  63  field  67  locations  72  survey area  Field  (E-W) (H ) z  79 through  Jacobs  calculations  81 84  vi i i  Page  Fig.  A.1  Graphical  Fig.  A.2  Hysteresis  Fig.  B.1  Schematic  Fig.  B.2  Calibration  and  analysis  of  harmonic  generation  94  loop  ...95  representation  c i r c u i t s  of  for  apparatus  harmonic  97  currents  GIC detector  98  F i g .  B.3  Calibration  Fig.  B.4  Schematic  B.5  calculations for mobile AF receiver system Sensitivity (mV/nT) c a l i b r a t i o n c h a r t for mobile AF r e c e i v e r system  111  Fig.  Contoured  118  l  charts  diagram  Fig.  C  Fig.  C.2  Theoretical  data  Fig.  C.3  Geomagnetic  f i e l d  Fig.  C.4  Base  103  of  c a l i b r a t i o n  c i r c u i t  and  data  Station  in  SCATCN  program  112  122  data  (22/7/81  -  23/7/81)  123  AF S i g n a l  (22/7/81  -  23/7/81)  125  ix  Acknowledgments  I  would l i k e t o acknowledge the c o o p e r a t i o n and a s s i s t a n c e  of Mr. R.M. Shier and Mr. Ron F i n n i e , of B.C. Hydro Research and Development, Surrey, B.C., and as w e l l the s u p e r v i s o r y personnel and t e c h n i c i a n s of M e r i d i a n s u b s t a t i o n , l o c o , B.C. For t h e i r a s s i s t a n c e i n the design and c o n s t r u c t i o n of the receiver the  i n s t r u m e n t a t i o n systems I acknowledge Dr. K. Tsuruda of  Institute  Tokyo;  of  A e r o n a u t i c s and Space S c i e n c e , U n i v e r s i t y of  Dr. K. Hayashi of the  U n i v e r s i t y of Tokyo; I  Geophysics  Research  Laboratory,  and Mr. B r i a n E. Chapel of U.B.C.  would l i k e t o thank Dr. J u l e s L a j o i e of Cominco L t d . f o r  initiating  the g e o l o g i c  i n t e r p r e t a t i o n d u r i n g one of h i s  visits  to U.B.C. I would l i k e to acknowledge the a d m i n i s t r a t i o n and s t a f f of the  U.B.C. Research  Forest,  where  much  of  the work of t h i s  t h e s i s was done. I would l i k e t o take t h i s space t o have  assisted  this thesis: students  me,  e i t h e r d i r e c t l y or i n d i r e c t l y ,  The people who  and  acknowledge  ended  up  started  out  with  those  who  i n preparing  me  as  fellow  as f r i e n d s - N e i l B i r d , Rob Coenraads,  Jim Horn, Tim Scheuer, and Kerry S t i n s o n ;  with t h e i r  presence,  the time I spent i n the Geophysics department here at U.B.C. was enjoyable  and  enlightening;  Miss Kathryn Belevsky,  for  i n d i r e c t l y f i l l i n g my n o n - t h e s i s hours and days. I would l i k e t o thank my for  his  invaluable  help  supervisor, with  every  Dr. Tomiya Watanabe, aspect  of  this  X  thesis;  suggesting  the  topic,  collecting  a n a l y z i n g the r e s u l t s , and p r o o f r e a d i n g  the  field  data,  the manuscript.  I would l i k e t o thank Dr. R.D. R u s s e l l and Dr. W.F. Slawson for  their  discussions  and  supervision  throughout the p e r i o d  spent on t h i s t h e s i s . Financial #17(GC-1),  assistance  was  provided  by  G.R.E.A.T.  co-sponsored by the S e c r e t a r i a t on Science,  and Development, Government of B r i t i s h Columbia, and Corporation.  The  project  was  Award  Research  B.C. Hydro  a d d i t i o n a l l y f i n a n c e d by U.B.C.  Committee on N a t u r a l , A p p l i e d and Health  Sciences  no. (21-9602).  1  Chapter I  INTRODUCTION  Geophysical of  the  e x p l o r a t i o n can  principles  (Heiland,  1940,  p.  systematic  efforts  about  earth's  the  observations  were  constitution expansive of  of  the  of  3).  be  considered  geophysics From  have  the  been  time  first  used  earth. Early  geologic  accuracy  coincident  with  advances  implementation exploration  known  as  and  need  an  "electromagnetic  fields  circuit  a  insulated  wire).  in contact  with  the  potentials  the  The  and  were  arose  in  The  (generally  at  the  a  of  and  measuring c i r c u i t opposed  currents are  The  methods, electronic  motivation as  for  economies  Wars.  The  induced coil  with  substantial  field  materials  and  location  deposits.  from  method."  a  shape  concerned  enhanced  of  information  the  f o r m of g e o p h y s i c a l (EM)  century,  gravitational  general  the World  measurement  g r o u n d , as  and  mineral  f o r raw  the  19th  to y i e l d  reliability  e a c h of  t h e s i s * d e a l s with  by  which  the  the  methods aim and  in physics  after  characterized in  and  particular.  came from  expanded d u r i n g This  in  of  to determine  development of e x p l o r a t i o n g e o p h y s i c s in  exploration"  studies  structures  increase  geologic  Magnetic  regional features;, present  local  "application  undertaken  interior. the  to  an  exploration method  is  electromagnetic  of  low-resistance  (or c o i l )  to p o t e n t i a l  measured u s i n g  does not methods,  come in  electrodes in  2 contact  with  exploration, supplying induced total  the  conductive  then,  consists  the primary field  field  directly effects  in  the  of  an  and  a  direction  due  the  source  coil  EM  of the  in  receiving  method current  measuring  of the a x i s  (primary  to c u r r e n t s induced  r e g i o n of the  The  alternating  r e p r e s e n t s t h e v e c t o r sum  from  localized  field,  ground.  of  coil  total  the c o i l .  The  originating  and  conductive  source  the  field  field)  of  any  secondary  bodies  (secondary,  or  in  the  anomalous,  field). Consider consists be  a  simplified  of t r a n s m i t t e r ,  r e p r e s e n t e d by a  electromagnetic inductive from may  receiver,  trio  (that  in  invariably best  to  (Telford  of  induction. i s , the  direct  good  The  source be  with by  electrical p.  the  fundamental  construction  connected  a coil  of wire coil,  different  components  stationary  reference c o i l  can  be  (the  secondary  primary  designed  field,  of  on  an  in  is the  by  i s usually originating  antenna),  ground.  though i t  The  The  detector  method  at  responds  shallow  also  shifted vicinity  can  consists  insulating  the t o t a l may  and  oriented  t o measure b o t h  field  coupled  depth  500).  complex. T h e i r  one  can  field,  conductors  diversified  have more t h a n  EM  induction.  devices are  may  circuits  which  and  (transmitter)  an  Receiving  to  exploration  buried conductor,  wire or a r a d i a t i n g  i t s signal  e t a l . , 1976,  EM  electrical  contact  receives  of  and  s o u r c e may  a current carrying be  version  so  field  be  in of  extremely  of an  frame. that  amplifier A  it  receiver measures  s i m u l t a n e o u s l y , and  employed.  amplitude  be  and  phase,  a  The  amplifier  phase  components  relative  to  the  a good c o n d u c t o r ) . O t h e r  3  possible  a m p l i f i e r designs  result  i n measured  components, o r i n ' e l i m i n a t i o n o f t h e p r i m a r y Transmitters of  long  cables,  current  most  battery source  field  sinusoidal (Telford  often  supplied  loops,  The  too i n e f f i c i e n t , and  p. 7 6 3 ) .  discriminate  produce  Some  the  conductivity  In  general,  a m p l i f i e r . The f r e q u e n c y  the distance  i s only  This  means  a very  Lower  coordinate  two  for frequencies  fraction  of a  can  be  depth  (Heiland, to  smaller  i s of the than  wholly  5 KHz  wavelength. are  disregarded  are disadvantages associated  with providing  f o r EM e x p l o r a t i o n ;  out  tedious  and  may  laying  be d i f f i c u l t  extra  involved  are  lack  1965, p. 4 4 5 ) .  c a n be cumbersome a n d d i f f i c u l t  of  energy  which o b s e r v a t i o n s  alternator  use  make  or t o i n d i c a t e  free-space  propagation  cost  5 KHz  s o u r c e and r e c e i v e r  of  is  to  ( T e l f o r d e t a l . , 1976, p . 5 2 0 ) .  made, t h e e f f e c t s  wires  of  Hz  frequencies  and deep c o n d u c t o r s  within  transmitter  depth  generally  interference  much  the regions  There  100  of the  is  frequencies  in  and West,  output from  that  (Grant  the  too  between  or l e s s ; small  range,  and  the  a l t e r n a t o r or  frequencies  of a s t r u c t u r e  of a k i l o m e t e r  this  shallow  coils;  and h i g h e r  systems  between  i n t h e form  circular  transmitter  e t a l . , 1976, p. 5 2 0 ) .  various  effect.  wires  by a g a s o l i n e - f u e l e d  and i n t h e l o w e r a u d i o  penetration  or  d e p e n d s on t h e t e c h n i q u e u s e d , desired.  transmission  order  rectangular  of  field's  of c u r r e n t - c a r r y i n g  powered o s c i l l a t o r - p o w e r  penetration  1940,  consist  ratios  i n m a c h i n e r y and  alternative  V L F and AFMAG,  use  of  transmission  i n rough t e r r a i n , t h e to transport,  personnel.  s o u r c e s h a s been  w h i c h make  long  a source  studied. remote  and t h e  Therefore  the  Two s u c h methods EM  sources  and  4  consequently  do  primary  field  i n the  method  is  thunderstorm range,  of  activity.  from  (audio-frequency  discharges The r e s u l t  signals  sferics;  less  than  similar coils  The  d e t e c t i o n systems, (one  narrow-band This  used  thesis  as  incorporates  presents  an  the  source  signal  relatively  low  sensitivity  considered  inaccessible,  immobile, power l i n e s  audio is  transmission line  and  set  methods  of  share  perpendicular a n d one o r two  as  a  the  area  than  of  line, source.  to  come  is  be  subsequently  needed.  Areas  interference  mind:  source.  select  and i t s  the  a  once from a  using  Several r e s t r i c t i o n s to  method  of  60 Hz  surveyed,  be s u r v e y e d  the primary  EM  schemes, a n d ,  number  strong,  signal  can  a  namely  detector to  of  This  remote s o u r c e  range,  due  method  source.  relatively  immediately  other  by  i n high-voltage transmission  consists  the  method  broadcast  AFMAG  experimental  the advantages of other  harmonics;  proposed  a  electromagnetic  i n t h e lower  transmission  1 Hz  i n the category  signals  and  generally  frequencies  high-voltage  about  i n the a m p l i f i e r .  remote  addition:  i n the ELF  f o r EM e x p l o r a t i o n , i n t h e  VLF  which uses t h e c u r r e n t a  5 Hz f a l l  to provide a reference signal),  filters  exploration lines  5-25 KHz.  worldwide  g r e a t e r than  uses  n a v i g a t i o n systems as s o u r c e s range  with  fields)  e t a l . , 1976, p . 5 3 4 ) . N a t u r a l  m i c r o p u l s a t i o n s . The V L F method  frequency  of t h e  magnetic  associated  with a frequency those  origin  i s a random s i g n a l  1 t o 1000 Hz ( T e l f o r d  denoted  certain  in  AFMAG  lightning  electromagnetic are  n o t need a t r a n s m i t t e r . The main  the  with the  source  is  must be i s o l a t e d  from  5 The this and  u s e o f a power  thesis,  only  and  as  sources  intensities  must  be  currents  with  with  when u s i n g  geomagnetic objectives  of  transmission  drawn  and  next  instrumentation  chapter  details  harmonic of  EM  using five.  survey  Also,  suggested presented included interest.  the  or,  more  is  source  thesis details  with  an  line  chapter  power  f o r use i n EM  research  directed  results.  the operation to t h i s  o f power  study.  Chapter  procedures.  of t h e e x p e r i m e n t a l transmission  as a  source, of  are  line.  systems three  involving results  of t h e method of  given  in  and t h e c o n c l u s i o n  of t h e  appendices  The f o u r t h  The  survey  information  the  work  EM  s i x . 'Three  to give d e t a i l e d  are  An a f f i r m a t i v e c o n c l u s i o n  and c a l i b r a t i o n  interpretation five,  the  concisely,  work, t o show t h e p r a c t i c a b i l i t y  i n chapter in  the system? These a r e e s s e n t i a l l y  in a particular  a transmission  loads  method o f o b t a i n i n g measurements, and  the r e s u l t s  currents  do v a r y i n g  of  as r e l a t e s  includes  harmonic  effect  deals  the experimental  of  and how  what  and e x p e r i m e n t a l  describes  fundamental)  be  the above q u e s t i o n s .  lines  power  the generation  variation  levels,  currents  use  the  i s , how  in  can t h i s  of t h i s  chapter  transmission  to  a v i a b l e and p r a c t i c a l  from t h e study  The  harmonic  thesis;  e x p l o r a t i o n ? The b u l k towards answering  the  be known; t h a t  on  this lines  (relative  t h e method? A l s o ,  activity  i f the a c t u a l  frequencies,  Additionally,  system a f f e c t  as suggested  s y s t e m a r e known. To  of d i f f e r i n g  t i m e must  field,  prove p r a c t i c a l  of the harmonics  studied.  t h e power  dealt  is  as a s o u r c e  c o n f i g u r a t i o n s of t h e power  harmonics  on  will  line  chapter  results i s thesis  is  to the text are  of p a r t i c u l a r  subjects  of  6 Chapter II  POWER SYSTEMS  2.1  General The  (figure  most 2.1)  consists  transformer mover  general  which  example h e a t , which  three  converts  falling  some  with  line,  form  2.3.  The  voltages  Vab,Vcd,Vef,  of  a f u n c t i o n of time  voltages  between balanced  any  of  s e t of c o i l s  (ab,cd,ef)  2.3(c).  a  The  system  rotation  of a  circuit  shaft,  i s u s u a l l y an  power s y s t e m s  consist  of  breakers  and  illustrated  in  ( f i g u r e 2.2). voltages in figure  is  2.3(a) r e p r e s e n t s bank  which  2.3(b) and a s a i s said  m a g n i t u d e and  two i s o n e - t h i r d c y c l e Vab,Vcd,Vef  hydraulic  a v a i l a b l e energy ( f o r  The g e n e r a t o r  transformer  in figure  generator,  or  r e s p e c t i v e l y . The v o l t a g e s  have e q u a l  voltages  a  system  and t h e l o a d . The p r i m e  of  associated  system  windings  figure  Practical  f o r each c o n d u c t o r  three-phase  figure  mover,  water, or f u e l ) i n t o  conductors,  A  three  prime  transmission  s u c h a s a steam d r i v e n t u r b i n e  (or a l t e r n a t o r ) .  disconnects  in  the  power  i n turn d r i v e s the generator.  AC m a c h i n e  as  of  of  banks, a h i g h - v o l t a g e  i s a device,  turbine,  form  can  are presented  phasor  time  (120 d e g r e e s ) . be  generate  diagram  t o be " b a l a n c e d " the  three  i f the  displacement That  represented  as  i s , the three  7  Prime Mover  o—o  Fig.  2.1  Transformer  Transformer  Load  Generator High-voltage line  :  A generator connected through transformers and a high v o l t a g e line to a d i s t a n t load (Eaton, 1972, p. 8 ) .  Of -P Ol— O  Ho-Or— Ho_Oj— Ho-Or— O Of Transformer Bank  Fig.  2.2  Disconnects  o o o  Circuit Breaker  Disconnects  Transmission Line  "^="  A three-phase transformer bank, the disconnect switches, and a three-phase circuit breaker connecting to a three-phase transmission line (Eaton, 1972, p. 19).  8 equal-magnitude  sinusoids,  with  respective  0 , 2 i r / 3 , and  phases  4ir/3. The and  coils  may  2 . 3 ( a ) a r e independant  in figure  be c o n n e c t e d a s d e s i r e d .  shown i n f i g u r e  2.4.  t o form a t h r e e - p h a s e  The  configuration  in  system  c o n n e c t i o n . The common p o i n t is  of a  neutral  and  windings  of a three-phase system  schematically  2.2  are connected i n  the in  is  letter  a  X,Y,Z.  conductors the  Y-connection  by  other  Y- ( o r s t a r )  is  N.  termed  The  Y-connection  the  secondary are  shown  2.5.  in figure  Harmonics The  designed  power  speed  frequency.  of the r o t o r  60 Hz  shown  The  here  configuration arrangement voltages  with respect  such  induced  as  in  (V ,V ,V )  from  B  figure  2 . 3 ( b ) , 2 . 3 ( c ) ) . With  mind,  i t can  exist  be  at  the n e u t r a l  prime  mover  i s governed  in  figure  other  of t h i r d position.  2.1 i s at  2.6)  (figure  be two  2.4.  each  of  that  in  harmonic  and  v o l t a g e s Vab,Vcd,Vef  figure 2.6,  a  by t h e a n g u l a r  equal (as  Due of  in  a  to the  the  three  magnitude and expressed  the Y-connection of f i g u r e  determined  only multiples  figure  A,B,C) a r e t h e n a r r a n g e d  will  C  the  the  The t h r e e l i n e  shown  coils A  from  in  to the stator  s i m p l y as phases  of the  degrees  circuit,  schematically  frequency  i n North America.  (mentioned  ±120  system  t o g e n e r a t e an AC v o l t a g e  specific  is  designated  with l i n e 2.4(b)  figure  each  Two common c o n f i g u r a t i o n s a r e  2 . 4 ( a ) the c o i l s  In f i g u r e  delta  of  in  2.4(b) in  a balanced three-phase v o l t a g e s and  The t r i p l e - f r e q u e n c y  currents quantities  9  F i g . 2.3  A three-phase system, (a) C o i l s i n which v o l t a g e s a r e g e n e r a t e d , (b) The s i n e wave v o l t a g e s produced i n the t h r e e c o i l s , (c) Phasor r e p r e s e n t a t i o n of the t h r e e v o l t a g e s ( E a t o n , 1972, p. 5 3 ) .  (a)  Fig.  2.4  (b)  Two common three-phase impedance connections, (a) D e l t a - c o n n e c t e d impedances. (b) Y-connected impedances ( E a t o n , 1972, p. 5 2 ) .  10  3-PHASE TRANSMISSION LINE  B  TRANSFORMER BANK  -ww-  F i g .  2.5  Three-phase  F i g .  2.6  Diagram Harley,  i  transformer  of an 1975, p.  system  idealized 6).  in  Y-connection,  AC m a c h i n e  (Adkins  and  11  are  c a l l e d  "zero  "zero-sequence"). cancel  at  the  phase-sequence" That  neutral,  components  at  Non-triple  harmonics  be  either  table  2.1  i s ,  this  a l l  but  due  to  point, are  while  termed  positive-sequence (Blume,  1938,  p.  PHASE BETWEEN  1 st 2nd  o, o,  3rd  o,  4th  o,  5th  o,  6th  o,  7th  o,  9th  o,  t r i p l e the  v e c t o r i a l  t r i p l e  or  (or  harmonics  w i l l  simply tend  addition  harmonics  three-phase  w i l l  quantities,  negative-sequence,  to of  add.  and  w i l l  as  seen  p.  39).  in  39).  TABLE  HARMONIC  quantities  2.1  ANGLE A , B, C  120, 240, (-120) 360, (0) 480, (+120) 600, (-120) 720, (0) 840, (+120) 1080, (0)  PHASE SEQUENCE  240 480 (-240) 720 (0) 960 (+240) 1 200 (-240) 1 480 (0) 1680 (+240) 21 6 0 (0)  Positive Negat i v e Zero Positive Negat i v e Zero Positive Zero  etc.  2.1  Table  A  and  Sequence  d i s t i n c t i o n  between that,  Phase  t r i p l e  on  a  made,  and non-triple  Y-connected,  currents  harmonics  is  are  Currents  exist  based  suppressed.  the  on  harmonics.  balanced  at  (from  system,  neutral  The existence  1938,  Blume,  the  above  This  is  third point, of  due  discussion, to  harmonic while  non-triple  the  fact  voltages  non-triple harmonic  12  quantities of  the  are  at  the  imbalance  not  of  The  neutral  of  equal  the  is  three-phase  considered  system  (in  an  which  indication Vab,Vcd,Vef  magnitude).  discussion  to  this  zero-phase  quantities  harmonics  (3rd,6th,9th,etc.)  superposition.  generally  The  point  has  which at  following  the  indicated  the  aspect  give  rise  neutral  position  discussion  to  of  t r i p l e due  regresses  a  to  step  and  (  points line  to  of  the  a  origin  transformer.  of  The  for  saturation  non-linearity  of  The  effect  can  core  material,  of  force  supplied  magnetic  flux  most  common  the  induced  of  A  for  However,  if  a  was  a  single  line  the  weight  of  hysteresis  current as  graphical  consists the  order  analysis  f i e l d  exists  only  of in  the  AC f i e l d s ,  an  p.  94).  results  transformer  results  in  the  magnetic  the and  with of  of  resultant  the  system,  secondary (one  1965,  of  (hysteresis).  force  of  power  cores  the  of  generator,  curve  the  relation  current  the  the  practice  and  power  transformer  assumed  this  saturation  a  in  (Say,  c i r c u i t  In  to  requirement  magnetizing  magnetizing  DC m a g n e t i c it  to  traced  densities  force  to  density.  one  is  designers,  due  magnitude a  regard  the  of  magnetic  sinusoidal  decreasing  now  system  stated:  line  by  flux/magnetic  the  a  reduction  secondary  Appendix  (until  imposed  the  by  with  induction  the  drives  form  in  of  flux  primary  with  is  power  a  represents  high  and  be  non-sinusoidal  harmonics  harmonics  use  design  Unfortunately  a l l  system.  transformers  economical  in  of  three-phase  The  power  origin  a  transformer the  resulting  current. point  For  the  symmetry),  odd  harmonics  only,  is  increased  (see  harmonic  content).  transformer due  to  the  core  primary  13 current,  exist),  symmetry.  In  the  the  hysteresis  latter  case,  curve  exhibits  a l l m u l t i p l e s of  no  the  point  fundamental  v exist,  and  the  particular  specific  h y s t e r e s i s curve  Therefore, ferromagnetic are  harmonics  due  core  expected  transformer.  are  to  i n the t o the  additional  content  in three-phase  pattern  of  the  three  delta-connected Y-connected  of  grounded  of  first  1976,  p.  the  power  core,  Harmonic due  all  currents  to  effects  interference  on  but  can  of  even  the  with  harmonic connection  suppressed  in  enhanced  in  are  harmonics  magnetic  field  (Hayashi  e t a l . , 1979).  by  a DC  operating  be  w i t h i n the  level  a t e a c h end  s e v e r a l hundred  flowing  (figure  conditions,  British  468)).  The  by  Barlow  i n 1847  telegraph earth  currents  been core  Practically,  current  bank  has  high-** m e t a l  60  the of  the  kilometers  i n the  this  in  the  signal  is  2.7).  natural large-scale earth currents  established  the  of  the  harmonics are  windings,  through a transformer  existence (first  triple  of a t r a n s f o r m e r  normal  which  and  i s dependant  occurrence  i s caused  ground c o n n e c t i o n  line,  the  level  field  Under  in  of  components  p r o t e c t i o n e q u i p m e n t . The  phases:  transformer  magnetic  loss  systems  the  windings.  t o a DC  a  exists  power s y s t e m d e s i g n e r ,  transformer  Theoretically, traced  harmonic  secondary c i r c u i t .  and  on  magnetization  secondary c i r c u i t  field  power  circuits  in  current  the  magnetic  exist  communication  in  depend  e t a l . , 1979).  non-linearities  exist  I f a DC  may  as  to  magnitudes  (Hayashi  m a t e r i a l s , odd  disadvantageous  such  harmonic  transmission in length.  is  course  system (telluric  Hz  well of  (Telford  The  known  studying et a l . ,  currents)  are  14  TRANSMISSION LINE  TRANSFORMER BANKS GIC  F i g . 2.7  J  POTENTIAL DIFFERENCE  GIC ( g e o m a g n e t i c a l l y induced ground of t r a n s f o r m e r bank.  current)  flowing i n  15  induced  by  fields  (in  these  large the  at  each  to  a  in  of  current  signal  since  it  stated,  the  is  connection  quasi-DC  harmonic  It  earth  to  e t ' a l . , is  at  by  by  becomes  (denoted  GIC:  leads  are  than  The  termed  the  60  Hz  l e v e l .  The  outside  diurnal and  can  variations auroral  t e l l u r i c  currents  currents.  As  in  the core  strength  concurrently  and  are  give  of  previously  with  ground  core.  rise  each  are  responsible  transformer then  the  ionospheric  transformer  currents  be  a c t i v i t y .  that  the  on  in  influence  in  the  originate  direct  t e l l u r i c  in  to  fluctuations  ionospheric  fields  stage  that  interested  in  geomagnetically  association  of  GIC  been  and  reported  studied  course,  to  changes  harmonic  geomagnetic  The  has  a c t i v i t y  1979).  this  designer  a  fields  change  known  as  currents  caused  current  grounds  transformer.  lower  eruptions,  thought  magnetic  found  solar  generally  magnetic  much  are  such  has  are  of  to  distances  two  connection  transient  a c t i v i t y  quasi-DC  quasi-DC  fields  and  f i e l d ,  the  the  the  Due  system.  phenomena  magnetic  in  (Hayashi  the  of  great  of  This,  ground is  s f e r i c s ) .  the  potential  connection  magnetotelluric  and  and  different.  frequency  periodic  induced  been  their in  magnetic  be  the  transformer's  with  currents;  in  ground  frequency  currents  lines, may  low  micropulsations  scale  magnetotelluric  correlated  for  line  the  earth;  earth's  large  the  inherent  The  Such  the  in  in  "quasi-DC"  of  transmission  end  currents  generally  range  time-varying,  involved  the  scale,  level  with by  the  power  quasi-DC  system  transformer  induced geomagnetic  Boteler  protection  (1979;  currents  currents). f i e l d to  be  a c t i v i t y  The has  published).  16  Even  though  frequently  in  associated  with  latitudes as  have  tripped  overloads  geomagnetic  effects  the  latitudes,  higher  power  systems  experienced safety  which  have  solar  relays blown  in  most  strongly  protection the  a c t i v i t y  and  open  occur  more  c i r c u i t  transformers  engineers  populated  related  middle  problems  breakers, (Fisher,  and  and 1981).  such even  17 Chapter  III  Experimental  3.1  Experimental  The this  Objectives  transmission  work  is  B.C.  line  used as  Hydro  Creek g e n e r a t i n g  station,  Meridian  and  3.2  show  the  U.B.C. R e s e a r c h Ears  Provincial  in  a  Forest  because  (5L82),  yet  sources  of  harmonic  current  ground  it  b a s e d on  levels are  at Meridian  location:  KV  near  through  near  Nicola  includes  southwestern  line  direction,  just  high-voltage remote and  most  line  from  GIC  the  (MDN)  the  transmission  on  the  situated  was  Access  made, w i t h  the  area  isolated  in  3.1  Golden  below  signals.  and  of  is  elecromagnetic 5L82  power  Figures  survey  in  terminal  s e c t i o n of  transmission  a  source  l o c o , B.C.  b o u n d a r y . The  is fairly  commercial  Experimental  500  exploration  5L82, w h i c h c a r r i e s  which  the  southern  is  otherwise  connection  personnel,  and  East-West  U.B.C. R e s e a r c h F o r e s t chosen  area,  P a r k . The  EM  station,  substation,  survey  generally  an  power l i n e  from t h e M i c a to  Procedure  cooperation  other  to a c t u a l transformer  of  B.C.  Hydro  substation.  measurements c a n  be  divided into  three  groups,  18  Fig.  3.1  Location of survey area (from B o t e l e r et a l . , t o be  for EM field published).  work  INSET  Fig.  3.1  Continued  Fig.  3.2  21 (a) Harmonic c u r r e n t l e v e l s on 5L82, a n d GIC made a t MDN s u b s t a t i o n ;  measurements,  (b) M a g n e t i c f i e l d s i g n a l s , i n d u c e d from AC c u r r e n t l e v e l s i n 5L82, made at a "base station" located i n the U.B.C. R e s e a r c h Forest, approximately 350 m ( p e r p e n d i c u l a r ) from 5L82 ( t h e s e signals are denoted "AF s i g n a l s " , a s t h e y l i e within the audio frequency range); a l s o g e o m a g n e t i c f i e l d components, m e a s u r e d a t the base s t a t i o n ; (c) M a g n e t i c f i e l d measurements ( u s i n g 5L82 a s s o u r c e ) on an a r r a y o f 66 " s t a t i o n s " t o c o m p l e t e an EM s u r v e y . The stations are located throughout the survey area ( f i g u r e 3.2). Consider  the o b j e c t i v e s of the experimental  work  of  this  thesis:  (a) The f i r s t o b j e c t i v e i s t o d e t e r m i n e t h e m a g n e t i c f i e l d strength as a function of the d i s t a n c e from t h e transmission l i n e . F o r t h e p r o p o s e d e x p l o r a t i o n method t o be e f f e c t i v e , t h e m a g n e t i c f i e l d s t r e n g t h must fall off as 1/r ( r i s t h e p e r p e n d i c u l a r d i s t a n c e t o t h e transmission l i n e ) . The w e l l known Biot-Savart law states t h a t t h e m a g n e t i c f i e l d due t o an i n f i n i t e l i n e c u r r e n t i n n o n - c o n d u c t i n g s p a c e f o l l o w s a 1/r r e l a t i o n . However in considering the r e a l , situation, this relation cannot be assumed, for in fact the transmission line consists of three equally-spaced conductors over a conducting earth. Therefore experimental verification o f t h e 1/r r e l a t i o n is necessary b e f o r e p r o c e e d i n g . I t s h o u l d be n o t e d t h a t a survey which monitored a single harmonic component (180 Hz) a t v a r i o u s distances from t h e t r a n s m i s s i o n l i n e (5L82) was u n d e r t a k e n i n 1979 (Watanabe et. al., 1981). The s u c c e s s of t h i s survey i n e x p e r i m e n t a l l y d e t e r m i n i n g a 1/r r e l a t i o n w a r r a n t e d f u r t h e r work, and a s i m i l a r s u r v e y , i n c o r p o r a t i n g more s o u r c e frequencies and slightly different methods, was done i n 1980. An additional objective o f t h e 1980 s u r v e y was to determine limits on t h e d i s t a n c e one c o u l d r a n g e from the transmission line and s t i l l receive a useful signal; (b) A n o t h e r primary o b j e c t i v e i n t h e e x p e r i m e n t a l work i s to ensure t h a t t h e c u r r e n t i n 5L82 i s in fact the source of the s i g n a l d e t e c t e d by t h e r e c e i v i n g u n i t ( l o c a t e d a t t h e base s t a t i o n ) . As s e e n from f i g u r e 3.1, t h e r e a r e a d d i t i o n a l power l i n e s i n t h e r e g i o n , though 5L82 i s by f a r the nearest t o the survey area. S i m u l t a n e o u s measurements o f h a r m o n i c c u r r e n t l e v e l s i n 5L82 and AF signals are needed to show that  22  transmission l i n e c u r r e n t h a r m o n i c s i n 5L82 a r e solely responsible for the primary magnetic signal received at the U . B . C . Research Forest base s t a t i o n . In addition, it s h o u l d be v e r i f i e d e x p e r i m e n t a l l y that the AF s i g n a l received at the base station is represented by the vectorial sum o f the c u r r e n t s in the three conductors of 5L82. Comparison of AF s i g n a l harmonic content with neutral current harmonic content s h o u l d show t h i s to be the case;  3.2  (c)  A third experimental objective is to show qualitative measurements o f G I C a t MDN s u b s t a t i o n and simultaneous magnetometer data taken at the base station. If possible, effects of G I C on h a r m o n i c c u r r e n t a r e t o be measured at MDN;  (d)  F i n a l l y , it is t o be shown t h a t the transmission line is an effective source f o r EM e x p l o r a t i o n . From the results of the experiment completed i n 1980 (previously mentioned in 3.1(a)),an extensive survey was planned for 1981 (for the results of each of these surveys, see Chapter 5).  Instrumentation  To U.B.C. AF  obtain Research  signals,  instruments were  simultaneous  and were  obtained  equipment  Forest)  (see  data  concerning  geomagnetic employed.  at  3.3  for  two  levels  substation, a  locations:  harmonic  a c t i v i t y ,  Current  Meridian  figure  (at  current a  number  and  levels, of  GIC  using  schematic  MDN a n d  the  GIC,  different  measurements the  following  representation  of  apparatus):  (a)  A four-channel audio-frequency direct was u s e d t o r e c o r d c u r r e n t l e v e l s . One reserved for (i) neutral current; (ii) ( i i i ) A-phase current with (iv) time code  (b)  recording device channel each was A-phase current;  harmonic current (that the 60 H z fundamental information;  A m u l t i - c h a n n e l FM r e c o r d i n g s y s t e m GIC l e v e l and time code information.  was  is, A-phase removed); and  used  to  record  23  SL82  AUDIO FREQUENCY TAPE (O)  FM  TAPE  (b)  A F  ANTENNA  o—t>  AUDIO FREQUENCY TAPE TIME CODE  N-S E-W  (0  HI-* V/F  CONVERTER  ~L  FM TAPE  (d)  AUDIO FREQUENCY TAPE  (e)  Z 3 COMPONENT MAGNETOMETER  AF ANTENNA  o—\t> •  o  WWV AUDIO RECEIVER PICKUP  F i g . 3.3  Schematic r e p r e s e n t a t i o n o f a p p a r a t u s .  24 Instruments activity,  used  placed  f o r AF  in  the  measurements and U.B.C.  Research  geomagnetic Forest,  are  field listed  below:  ( c ) An AF a n t e n n a - r e c e i v e r u n i t was used to detect the magnetic field due to harmonic current in the t r a n s m i s s i o n l i n e . The signal from the antenna was recorded on one c h a n n e l o f an a u d i o - f r e q u e n c y d i r e c t r e c o r d i n g m a c h i n e , w i t h t i m e c o d e on a n o t h e r c h a n n e l ;  (d) A t h r e e - c o m p o n e n t m a g n e t o m e t e r , set up at the base station, was used to measure the geomagnetic f i e l d variation. The i n f o r m a t i o n was recorded on three channels of an FM tape system, w i t h a n o t h e r c h a n n e l used f o r time code.  The  total  harmonic  simultaneously be  analyzed  recorded for  analog-input levels  indicate  that  at  by  MDN  of  The  two  AF  show in  field,  and  content  in  signals,  signal  over  since  the  current  equipment  the  used  lab the  a period  correlation  the line  North-South lies  levels  then  using  an  to  will  station  is  measurements magnetometer  component  of  the  East-West. included  i n 5L82 as  in this  can  of t i m e ,  GIC  are  particular  d e t e c t e d a t the base  direct  particular  signal  t a p e s , and  c u r r e n t s i n 5L82. A l s o , a  AF  Comparing  s t a g e o f e x p e r i m e n t a l work  harmonic  the  audio-frequency  analyzer.  the harmonic  next  s o u r c e . The  the  the  measurements,  using  spectral  should  geomagnetic  on  spectrum  harmonic  induced  current level  survey  an  EM  the p r i m a r y  survey inducing  follows:  (e) A mobile AF receiver, using a battery-powered, light-weight c a s s e t t e r e c o r d e r ( c h a n n e l one f o r t h e AF s i g n a l , c h a n n e l two f o r r e c o r d i n g t i m e i n f o r m a t i o n ) ;  25  3.3  (f)  A s t a t i o n a r y AF r e c e i v i n g u n i t , l o c a t e d at the base station, to use as a r e f e r e n c e s i g n a l f o r harmonic amplitudes ( l i s t e d p r e v i o u s l y in section 3.2(c));  (g)  A t h r e e - c o m p o n e n t magnetometer, t o measure geomagnetic f i e l d a c t i v i t y ( l i s t e d p r e v i o u s l y i n s e c t i o n 3.2(d)), a good p r a c t i c e i n e l e c t r i c a l e x p l o r a t i o n m e t h o d s .  C a l i b r a t i o n Procedure  Accurate quantitative  calibration measurements  procedures  are  by  calibrating  s y s t e m as is  through  current as  the  current  secondary  probe  t o an  current  AC  probe  transformer,  and  attached  to a t e s t  attached  For  The  the  data  data  and  reliable  test relation  particular important  of  circuit in  be  noted,  recording  access  set  to  5L82  three  400:1  A device  known  of  recording from t h e  line  purposes, the  current data  the  level  current the  p r o b e s were  is  accurately  at  generator  each  harmonic  f o r both  recorded  signal  one  from  signal  analysis  corresponding however:  a  AC  the  current  includes  an  periods, A-phase  to a  ( s p e c t r a l a n a l y s i s of  the  and  inductively converts  line  i n which  i s known between  f a c t s must  at  a  i s attached  same method of  f r e q u e n c y and  done  shows the  data  to a  test  calibration  frequency. Using  l e v e l s was  i n f i g u r e 3.3).  calibration  circuit  ( f i g u r e 3.4>. allows  CT  During  another probe  position.  3.3  i s u t i l i z e d , , which  is  the  amplifying,  windings  (labelled  voltage.  neutral  which  detecting,  unit. Figure  transformers  a current  known  the  a complete  for  involved.  Determing q u a n t i t a t i v e harmonic c u r r e n t MDN  essential  on  current  real  signal), tape  at  i n 5L82.  a a Two  26  as  (i)  E a c h c u r r e n t t r a n s f o r m e r i s c a l i b r a t e d a t 400:1 only at t h e 60 Hz f u n d a m e n t a l ; i t must be assumed that the same ratio holds f o r harmonic c u r r e n t s as w e l l ( t h a t is, in the frequency range 60 Hz-1 KHz). This assumption can be s u b s t a n t i a t e d , however, by s p e c t r a l comparison of the neutral current and the AF signal; s i m i l a r s i g n a l s would i n d i c a t e the r e l i a b i l i t y of t h e a s s u m p t i o n , s i n c e t h e AF s i g n a l i s an i n d i c a t i o n of a c t u a l h a r m o n i c c u r r e n t s i n 5L82;  (ii)  The n e u t r a l c u r r e n t d i s c u s s e d i n t h i s s e c t i o n does not exist, per s e , i n 5L82, s i n c e 5L82 c o n s i s t s of t h r e e s e p a r a t e c o n d u c t o r s A, B, and C. The neutral current represents the vectorial sum of t h e c u r r e n t i n the t h r e e c o n d u c t o r s . I t e x i s t s i n the c u r r e n t transformer circuit, since the secondary windings of the t h r e e c u r r e n t t r a n s f o r m e r s on 5L82 are Y-connected (as in f i g u r e 3.3). The a d d i t i o n of the t h r e e m a g n e t i c f i e l d s ( g e n e r a t e d by c u r r e n t s i n conductors A, B, and C) at the AF antenna will appear to originate from a " n e u t r a l c u r r e n t " i n 5L82.  The  GIC  the  measuring  system  harmonic c u r r e n t  Hall-effect connected  transducer  t o the  circuit  is  i s c a l i b r a t e d i n the  detection  device  transformer again  (discussed  used  to  is  current  thought  discussed "in  the The  of  an  i s passed  that in  "on  this  site"  a p p a r a t u s used antenna, to  record  station.  The  calibration  placing  the  antenna  on  tape.  The  and  f o r the  the  in a  the  this  once,  detector of an  EM  of  and the  (direct  field  signal  system  recording EM  is a  which i s A  test entire  which  a  3.4).  It  e n t i r e system,  as  to  on  (figure  relying  components.  exploration DR  in  was  survey  the  mobile  consisted  recording) at  each  tape mobile  accomplished  s i n u s o i d a l l y - v a r y i n g magnetic  frequency  calibration  and  total of  calibrate  superior  individual  amplifier,  recorder  known s t r e n g t h  of  is  B)  5L82.  calibration  section,  lab", c a l i b r a t i o n  the  manner  detector  of  system at  through  GIC  i n Appendix  ground c o n n e c t i o n  detection-amplification-recording known DC  s y s t e m . The  same  by  field  of  subsequent s i g n a l system  and  base  CURRENT HARMONICS CALIBRATION CIRCUIT CURRENT PROBE  SIGNAL GENERATOR  D  (AMPLIFYING & RECORDING SYSTEM  GIC CALIBRATION CIRCUIT DC SOURCE  . 3.4  0  HALL-EFFECT TRANSDUCER  5°  Harmonic c u r r e n t and GIC c a l i b r a t i o n  I AMPLIFYING & RECORDING SYSTEM  circuits.  28  station  system  detailed  discussion  is  in  found  is  Appendix  further  discussed  including  graphical  B.  in  section  results  of  5.2,  and  a  c a l i b r a t i o n  29 Chapter  IV  EXPERIMENTAL  4.1  G I C s  detected  Section data  and  to  associated  5L82  described  harmonic  substation  chapter  3.2  in  system  current  data.  and  data  to  w i l l  Substation  measure  The  record  B . C . Hydro  specific  Meridian  a  detect  with  at  RESULTS  system  GIC  and  transmission  be  and  presented  was  record set  up  harmonic line  and  GIC  at  MDN  currents  5L82.  In  this  discussed  in  the  text. The presented is  theory  for  in  previous  shown  the  e x p l i c i t l y  measurements of  5L82.  0.l5y ±1  at  Amp.  a  is  also  geomagnetic during  geomagnetic  line. f i e l d , the  exists f i e l d  figures  a  150s)  is  clear  though  in  of  The 4.1  and  it  4.2  the  is  the  variations.  is  a  N-S  another  event  to  of  of  the of  is  (about  level  in  record  line,  5L82  v i c i n i t y  component  Nevertheless,  reasonable  in  the  GIC  f i e l d  was  simultaneous  GIC measured  transmission It  in  lines  GIC  with  for  the  geomagnetic  measurement.  of  geomagnetic  is  the  4.2, f i e l d  responsible that  transmission  existence  moderate  influences  Figure  time  GIC in  geomagnetic  4.1,  which  of  chapter.  in  figure  f i e l d  o r i g i n  changing  of  It  Amp  the  period  transmission  ±1/8  of  In  geomagnetic  quiet  the  the E-W  GIC  and  relatively a  due  current to  expect  of  small that  a  30 quasi-DC during  current a  of  Harmonic  several  Current  Harmonic 5L82  presented  indicate  current  (A-phase)  harmonic point.  To the  in  of  currents  The  figures  least  data  4.3(c), f u l l y  following  is  to  ±2  active  Measurements  levels this  Amps  could  period,  exist  with  in  5L82  possible  to  shown  understand  to  the  in  the  should  the  be  11th  way  and in  noted:  transmission 4.3(a)  11th  4.3(b)  terms  4.4(c),  with  Figures  Figures  up  Meridian  associated  up  5L82. (also  in  section.  levels  4.3(d),  items  ±1  Amps.  current  are  phase  at  geomagnetically  fluctuations  4.2  of  harmonic  and  at  harmonic  4.4(a) in  4.4(b)  harmonic) of  and  line  one depict  the  neutral  spectra  in  4.4(d). which  the  data  is  presented,  '  (a)  Each trace represents the current level ( i n RMS A m p s ) measured at a p a r t i c u l a r harmonic frequency, as a function of time (the last trace gives time code information).  (b)  The c u r current which multipl factor  (c)  Each trace is r e c o r d e d on a l o g a r i t h m i c amplitude scale for relative c a l i b r a t i o n . The major divisions correspond to a 10 d B change in current, with the -20 dB mark on e a c h t r a c e labelled on the right side with the c a l i b r a t e d c u r r e n t measurement. An a c c e p t a b l e S/N r a t i o is in the range from 0 dB to -50 dB for the A-phase system (-10 dB to -60 dB for the neutral current system). Note that a relative difference of 20 d B c o r r e s p o n d s to a factor ten in current; that is, a level of -40 dB i s 1/10th the c u r r e n t of -20 dB, and -60 dB i n d i c a t e s 1/100th the current of -20 dB. The b a s i s of this convention is that the signal given i n dB  rent stated for each harmonic represents the in 5L82. That is, the a c t u a l current measured, is from the current transformers, has been ied by the constant current transformer (400).  31 is in fact the RMS a m p l i t u d e of t h e v o l t a g e s i g n a l recorded on tape, using the definition: dB=201og(V/Vref), where the reference voltage V r e f = 1 . 0 Vrms. Due t o l a c k of space a full current scale on each h a r m o n i c i s n o t i n c l u d e d , however f u l l i n f o r m a t i o n i s a v a i l a b l e w i t h use of the calibration charts (Appendix B ) . To e n s u r e c l a r i t y i n r e a d i n g the d a t a , r e f e r t o f i g u r e 4.5. The c o n v e n t i o n a d o p t e d here i s constant throughout t h i s r e p o r t . (d) The data i s also presented i n the s p e c t r a t o g i v e an o v e r a l l view of t h e harmonic c u r r e n t s . In regard  addition, to  (f)  the  following  f i g u r e s 4.3(a),  4.3(b),  form of harmonic relation among  information  should  4.4(a),  4.4(b):  and  be  noted  in  To s a v e t i m e i n p r o c e s s i n g t h e data, each trace was analyzed individually at four times real time. T h e r e f o r e t h e s i g n a l was sampled a t 1/4 the r a t e of a corresponding real time signal, which p r o v e d t o be s t i l l a l a r g e enough s a m p l i n g r a t e t o a v o i d any l o s s of information. The data shown in f i g u r e s 4.4(a) and 4.4(b) cover, a s h o r t e r t i m e segment, however, and t h u s were a n a l y z e d i n r e a l t i m e .  (g) F l a w s i n t h e d a t a of f i g u r e s 4.4(a) and 4 . 4 ( b ) , caused by a f a u l t y c o n n e c t o r , a r e d e s i g n a t e d by m a r k e r s on the time trace, and do not represent any changes in harmonic c u r r e n t l e v e l . With data  in  general  the  preceeding  terms terms  harmonics  (in  establishes of  relative  harmonic  the  a  fact  magnitude strengths  decrease with h a r m o n i c can  the  can  strength.  current  phase)  look  As  should  exist,  hysteresis  relationship.  that  odd  harmonics are  current  odd as  than  harmonic  the  data  strongest  even c u r r e n t  currents  shows t h a t  the  odd  due  to data  generally  harmonics.  not  the  fifth  in  at  The  do  A-phase harmonic  at  discussed  strengths  the  stronger  of  order', be  only  particular  in  i n mind, one  current  i n s e c t i o n 2.2,  non-linearities  order  of  comments  an The  necessarily or  current.  seventh  32 The c u r r e n t given  strengths  representing  i n f i g u r e s 4.3(b) and 4 . 4 ( b ) . The l a r g e 60 Hz component i s  a measure o f t h e i m b a l a n c e if  the three  only  the n e u t r a l p o s i t i o n are  current  was m o n i t o r e d  some i n f o r m a t i o n  imbalance waveform  i t w o u l d be  zero  p h a s e s (A, B, and C) were o f e q u a l m a g n i t u d e .  A-phase  current,  of t h e system, s i n c e  of does  not  i n a d d i t i o n t o the n e u t r a l  on t h e i m b a l a n c e  60 Hz c u r r e n t  i s lost.  among t h e t h r e e  consist  solely  neutral  currents  Since  of  Due  to  the  phases, the n e u t r a l  zero-phase  sequence  currents. The  strongest  occur  a t f r e q u e n c i e s of  60 Hz, 180 Hz, 300 Hz, and 420 Hz, o f w h i c h  only  zero-phase  the neutral  is  s e q u e n c e q u a n t i t y . However,  t h e sum o f t h e c u r r e n t  only  zero-phase  i n a s i n g l e phase  Harmonic Frequency  i n the three  currents  that  is  a  current  phases, i t i s e s s e n t i a l l y  are stronger  i n the n e u t r a l  than  (see t a b l e 4.1).  A-Phase A(rms)  Neutral A(rms)  13:39-14:17 3/3/81 60 Hz 1 20 Hz 180 Hz 240 Hz 300 Hz 360 Hz 420 Hz 480 Hz 540 Hz 600 Hz 660 Hz  since  180 Hz  800 0.40 2.2 0.50 7.0 0.38 4.6 0.36 0.45 0.45 0.35  T a b l e 4.1 Maximum H a r m o n i c Meridian Substation.  LT  34.0 1.6 7.0 0.42 1 .9 0.6 1 .9 0.42 0.24 0.24 0.35  Current  A-Phase A(rms)  Neutral A(rms)  13:50-14:15 -11/6/81 880 0.40 4.5 0.32 3.5 0.22 4.6 0.10 0.35 0.54 0.22  Measurements  LT  42.0 1 .7 9.8 0.90 1 .9 0.72 3.6 0.35 1. 1 0.20 0.70  on  5L82  at  33 The three and  180 Hz  neutral  t i m e s t h e A-phase  420 Hz ( a s w e l l  current Other  strength  the  less  than  is  Similar  about  results in  that  zero-phase c u r r e n t s  tend  results  only  strength  i s greater  0.1  that  results  and  ratio  component in  the  fact  recording  of  neutral  each  AF  likely  the  values  antenna o b s e r v a t i o n s  due  small  indicating  currents  currents  (a c u r r e n t  a s 2.5 mA  should The  i s questionable  whose  innaccuracies  due  forthis  (see s e c t i o n 5.2).  o f 1.0 t o the  (less  than  o f t h e 120 Hz  reason,  with  1.6 Amps  i t i s an e v e n ,  be s m a l l  accuracy  correlate  in  The 120 Hz c u r r e n t  p e r i o d s ) , though  each.  not  consistent  i n A - p h a s e and a b o u t  and t h e r e f o r e  do  to  transformer).  ( f o r both data  values  and  o f t h e f u n d a m e n t a l . The  i s detected  current  in  in  i n t h e examples g i v e n , or  strength  very  line  f o r example)  current  that  0.35 Amps  that  harmonic  1.0 Amp  the  a r e most  n o n - z e r o phase' c u r r e n t  neutral  of about  i t must be n o t e d  a p p e a r s t o be 0.40 Amps  1.0 Amps,  component  t o i n c r e a s e a f a c t o r o f t h r e e when  about  of  i n the transmission  400:1  360 Hz  0.72 Amps i n t h e n e u t r a l .  for particular  per cent  inconsistent detecting  occur  neutral  strength.  A-phase a n d t h e n e u t r a l , r e s p e c t i v e l y ,  summed a t t h e n e u t r a l . However,  about  the  a r e 360 Hz a n d 540 Hz ( s e e  f o r 540 Hz show c u r r e n t s  Amps  a t 300 Hz  t h e A-phase c u r r e n t  0.22 Amps a n d a b o u t  1.1  while  60 H z ) ,  4.4(a) and 4.4(b) - 1 1 / 6 / 8 1 ) . The  A-phase  i s of the order of  strength,  fundamental  examples of z e r o - p h a s e c u r r e n t s  figures  Amp  strength  180 Hz c u r r e n t  as is  current  plus the  simultaneous  34 4.3  Effects  It  o f GIC on H a r m o n i c  was  shown  transmission hysteresis  line  fluctuations harmonic  harmonic  currents. exist  currents  0.05% o f  of  particular the  the  the  is  supports  existence  of  current  shown t o be e x c e e d i n g l y  level), small.  in  GIC  accompanied  by  be  the  (see  harmonic  nearly  even  0.50  Amps, t h e n d r o p s t o 0.10 Amps, and s u b s e q u e n t l y  current  Neutral  o f about levels  current  are unaffected fluctuations,  to follow a s l i g h t l y  currents  i n t h e A-phase  affected, GIC  differ  pattern  Odd h a r m o n i c  from t h e A - p h a s e  currents. t o about  resumes i t s passes.  interestingly  b u t t h e f l u c t u a t i o n s i n even h a r m o n i c  activity  is  Odd  by t h e GIC e v e n t .  different  conductor.  measured  rises  0.40 Amps a s t h e GIC e v e n t  observed  currents increase  even h a r m o n i c initially  order  currents are  LT, 3 / 3 / 8 1 ) ,  t h e A-phase  harmonic  240 Hz h a r m o n i c , w h i c h  even  the content  harmonic  (13:43  odd  one p e r c e n t  Note  level  the  and 4.3(a))  data  even  harmonic  A-phase  t o be o f  of  the data  however. A m o d e r a t e  fluctuations in certain  previous  that  even  t h e even h a r m o n i c  f i g u r e s 4.1 current  creating  Compared w i t h  to a  source  theory  small  (up t o  the  The change  Particular  I t i s only  a r e a f f e c t e d by GIC a c t i v i t y ,  with  very  level.  currents  of  c u r r e n t s . However  i n the the data  that  concurrently  core.  the  o f GIC a c t i v i t y .  60 Hz c u r r e n t  o f GIC i n  deformation  was shown t o  i n single-phase  a r e shown  activity  a  the e f f e c t  transformer's  data  odd h a r m o n i c  60 Hz  that  quantities, in particular  The  irrespective  of  of  the  i n harmonic  indicates  currents  of  h y s t e r e s i s curve  harmonics would also  s e c t i o n 2.2  transformers  curve  non-symmetric  in  Currents  even  enough,  than currents  were  harmonic a r e not  c u r r e n t s due t o  harmonic  components.  35 In is  the  case of the n e u t r a l c u r r e n t ,  t h e 360 Hz component  pattern  of  decrease  ( t o about  level  a  (see  small  f i g u r e 4.3(b)),  increase  (to  at  the  end  component  i n the n e u t r a l current,  the  event.  attributable involved. neutral  The a p p a r e n t  t o the  low  Therefore  the  shows an e f f e c t  three  smaller  effect  o f t h e GIC e v e n t  it  i s very To  one  conclude  GIC  this  with  picture  and  are  geomagnetically more d a t a and  determine  all  three  followed  to  inconsistency  strengths  of  zero-phase  its  a  by a  previous  GIC e v e n t . The 240 Hz  however, shows  no  effect  i n these  the  currents  component  since  of  results i s  harmonic  360 Hz  i nthe  i t i s t h e sum  t h e 240 Hz n e u t r a l component  s e c t i o n , i t must moderate  harmonic can  harmonic quiet  of t h i s  the  because, not being  of  incomplete 4.4(b)  of  follows  of  shows no  a zero-phase  current,  i n the n e u t r a l .  event,  simultaneously  0.80 Amps)  o f t h e GIC e v e n t  currents;  small  which  0.2 Amps), and a r e s u m p t i o n  (0.60 Amps)  GIC  t h e h a r m o n i c most a f f e c t e d  type  be s a i d  magnitude,  current  be p r e s e n t e d current  that,  levels, (note  data  was only  that  w o u l d be n e e d e d t o c o m p l e t e effect  only  recorded a  rather  f i g u r e s 4.4(a)  recorded  time - see f i g u r e 4 . 4 ( e ) ) .  the general  since  during  Obviously the  a much  picture  o f G I C ' s on h a r m o n i c c u r r e n t i n  p h a s e s of a t r a n s m i s s i o n  line.  14=00 L'  3381  F i g .  4.1  Effect (3  March  of  geomagnetic  1981).  Bottom  trace  f i e l d is  on  time  GIC code.  in  5L82  \y at  0.1  UUiiilliJiHiitillkll  Fig.  4.2  •^i-i..ii.niii:i)iii W I R I I I W l l l l l l 11 If I • M { J f I ! ! l i n i l T I  Effect of geomagnetic field (4 A p r i l 1981). The magnetic are the same as i n f i g u r e 4.1  on GIC in 5L82 f i e l d and GIC s c a l e s  'Vaflo 5:00  ui  ll  CO  (rms) 60  Hz  i ili.,iuil.luuum  ;!!!;!imi!i!i!!|^!!:!;!!j:HJi!!l!  HiiliilliH  ffiltifiJMjjiiD  120 Hz 180 Hz 240 Hz 300 Hz  m  360 Hz  —  m WW-WW  iiillMliifli  ' 1 • •  k f n i . u ifflti}Hi«  !!!!! _js4-*+T"f * •' ' • :  ill  miujin'Hili  420 Hz 480 Hz 540 Hz  600 Hz 660 Hz  •" " " " j — *  m  |;!it.il;i:::::::!;:i:!n!rn:m:ffit  M.  •  i a.  .2:00 UI 14:00 L1  3-3-81  Fig.  4.3(a) A-phase h a r m o n i c c u r r e n t l e v e l s ( 3 M a r c h 1 9 8 1 ) . On the vertical scale, two d i v i s i o n s c o r r e s p o n d t o a f a c t o r t e n i n c u r r e n t . Bottom t r a c e i s time code.  -300 - 9.0 5.5  60  Hz  120  Hz  180  Hz  540  Hz  600  Hz  660  Hz  mm ifitiiiiBtliili B  iiiiii;iiiiiii$iiiiiui«af£«ii>iiaiii«  • 14:(in LI  3-3-81  F i g . 4.3(b) the  Neutral  v e r t i c a l  current.  harmonic  scale,  Bottom  trace  two is  current  divisions time  code.  levels  correspond  (3 M a r c h to  a  1981).  factor  ten  On in  CO  X  o CO  JV1  o «—«  JV)  X  o  oo  TV)  JVI  JVI  X  X  X  X  X  X  X  o  o o CO  o CO  o CM  o  o  sr  m  O O CO  CM  00  HARMONIC FREQUENCY  Fig.  4.3(c) S p e c t r a l  representation  of data of 4.3(a).  X O CO CO  41  Fig.  4.3(d)  Spectral  representation  of  data  of  4.3(b).  (rms)  60  Hz  120 Hz  -300 •  i  ,  , , , ,  ,  1  ;^^^^"^'^^WIMWMMMIMf^^MMJ^^MM||IHMM^^  -ao  180 Hz  -5.5  240 Hz fe  -4,7  480 Hz 540 Hz 600 Hz 660 Hz  14:00 LT 11-6-81  Fig.  4.4(a)  A-phase  harmonic  the v e r t i c a l tactor ten xn  current  scale, current.  levels  (11  June  1981)  two d i v i s i o n s correspond'to Bottom trace is time code  On a 1  0  1  60  Hz  120 Hz 180 Hz 240 Hz 300 Hz 360 Hz 420 Hz 480 Hz 540 Hz 600 Hz 660 Hz  i 111 ij weak  21:00 UT| 14:00 LT  n-G-81  Fig. 4.4(b) N e u t r a l h a r m o n i c c u r r e n t l e v e l s the v e r t i c a l scale, two d i v i s i o n s correspond current. Bottom trace is time code.  (11 to  June 1981). a factor ten  On in  (rms)  44  Fig.  4.4(c) S p e c t r a l r e p r e s e n t a t i o n  of  data  o f 4.4(a)  45  F i g . 4.4(d) S p e c t r a l r e p r e s e n t a t i o n of data of 4 . 4 ( b ) .  Fig.  4.4(e) G e o m a g n e t i c measurements  field during current harmonic o f 4.4(a) a n d 4 . 4 ( b ) , (11 J u n e 1981). CTl  H—I—I—I—l-H—r—i —i—I—I—h J . : : I.  HARMONIC FREQUENCY  H I TTTT1  !!::|iH=  i:::  ] :;: : :i •  i n : rff!  -ITT  " ; -Iii! . . . . .!.:. . J: •;  ::;T:::I iiiiliirl •'  I  TTTT|TTTT  ; i: •  iii;  '  wvU  ........ -i — t  :  I I I I I I I I I I I I I I I I I  m$  ^ H l ! iijipnjHiilili!  LfiAC  • -frr .::i::::  "T"  :: i :  :  "  i  .  ]  ] "  :  :  -ii  ::n  : :i  TTTT :HI rm  •:t:  • • :•• • : : . . : : : ; [ : ' : :  TTTT  I  iiiuirmi  :fnf:TT! ;;;;):•:  m$  ITTTT i i III! i i l i i i i : :  I-" I  - 20 dB - 30 dB - 4 0 dB - 50 d B - 60dB - 70dB  1I ! "  REFER TO CALIBRATION CHARTS (APPENDIX B) FOR dB - Amps CONVERSION  Fig.  4.5  Correspondence calibration.  of  relative  values  and  current  48 Chapter  EM SURVEY:  5.1  I n t r o d u c t i o n t o EM  V  EXPERIMENT AND  RESULTS  Experiment  The p r o p e r t i e s o f a g e n e r a l method of EM e x p l o r a t i o n studied  in  primary  coil,  Chapter  1).  methods  terms of a s e t o f m u t u a l l y receiver The  and  primary  current  results  high-voltage  coil,  of an EM  transmission line  field.  Suggestions  e x p e r i m e n t a l method w i l l  inductive c o i l s ,  and s e c o n d a r y  chapter  coil  describes  i s used  as  further  the  work  of  survey.  spatial the  prime changes  total  primary  objective  EM methods  fall  any EM t e c h n i q u e  i n the secondary  field.  field,  of  Obviously  generally into  field  a function  signal. vertical  and  time  variations  For c o n t r o l l e d antenna,  must  of b o t h  two c a t e g o r i e s :  s u c h a s AFMAG and V L F , t h e p r i m a r y uniform,  through  something  t o improve  the  which  of the r e s u l t s  i s to  determine  measurements  of  be known a b o u t  the  space  and t i m e . Most  i s considered  monitored  s o u r c e methods s u c h a s  and l o n g w i r e ,  the  f o r remote s o u r c e  field  are  of  the chapter,  by s u g g e s t i n g a g e o l o g i c i n t e r p r e t a t i o n  The  i n which a  source  concludes t h e EM  experimental  survey  the  be d i s c u s s e d w i t h i n  denoted  (as d i s c u s s e d i n  reconnaissance  for  c a n be  as  methods spatially  a reference  horizontal  the source of the primary  loop, field  49 is  well  then The  be  controlled calculated  methods  function  of  time the  transmission source  In  frequencies  in  disadvantage source  is  analysis  l i e s both  primary  the  secondary  for  further  5.2  much  f i e l d .  to was  transmission detected  by  receiver was  a  to  done  in  total  f i e l d  and  time  be  be  major to  f i e l d  5L82  in  survey test  was  of the  the  66  1  KHz).  However,  primary  a  mobile  apparatus of  figure  5.1  within  the  survey  area).  which  the  amplitude  a l . ,  at  1981).  nine The  strength-distance  f i e l d  for  of  results  relation  The  the  of  this data  much  as  of  suggestions  stations  in  1981,  and  ensure  that  the  primary  f i e l d  location  f i r s t 180  this l / r  of of  effects  up  v e r t i c a l the  work to  of  experiment  Hz  throughout of  of  making  the  the  stations  a  determination  well  source  discrete  study,  showing  (see  measured  remote  -  as  Apparatus  a  of  results  presented,  of  number  in  a  simplifies  a  introductory  spent  f i e l d  reconnaissance  dependant,  and  receiver  et  this  only.  high-voltage  advantage  the  Experiment  done  1979  (Watanabe  that  method.  line  was  fact  can  of  Hz  the  the  the  (60  For  which  inexpensive  range  w i l l  the  f i e l d  primary  commercial  consists  Experimental w i l l  has  the  only,  improve  stations  component area  f i e l d  a  primary  coordinates  making  fast,  the  analysis  Preliminary  work  AF  d i f f i c u l t .  work  Prior  a  spatially  quantitative  the  in  of  source  lower  spatial in  EM s o u r c e  the  The  coordinates  use  being  the  more  The an  of  succeed  spatial  as  addition  transmitter.  function  here  data.  line  the  a  or  technique,  method.  the  as  mentioned  of  analysis  at  survey  indicated a  distance  50 of  about  work  eight  spurred  EM  source,  by  this  from  interest  and  done  improved  the  served  as  an  done  in  1980  by  the  year  recording  frequencies  provided  were  at  made  nine  stations  1981  survey  13 of  the  of  mobile  66  survey).  points (three  and  (numbers  10  years  data  of  station  the of  180  should  be  measurement station  available,  and  surveyat  reading  a  each for  the  of  the  1979  lines  work  are  as  an  expressed  varied  in  the  mobile  was  data  mobile the  the  and  1981). role  time  data  that  more  station  same  general  was for  (results  of  the  was  was  weighted  the  trend  of  (ii)  the  three Lake  trend  addition,  in  1981),  1/r  the  1981  used  to  year region  (for the  ' base  survey. show  two  In that  the  duration  plotted  d i r e c t l y .  extensive,  each  the  3  ±10% over  data  of  1/r ;  1/r  base  extensive  and  Alouette  the the  AF  stations  ,  over  In  the  5.2  2  in  an  general  the  f i t  station  much  13  1 / r , 1 / r  in  harmonic  measurements  of  1980,  the  given;  less  the  on was  including  and  figure  (i)  a l l  improvements  1979,  station  by  area,  5L82,  in  important  base  monitor  survey  in  expanded  technique  measurements  the  1980  thesis  receiver  Further  noted:  not  more  years,  strength  survey, 1981  do  to  Mobile  measurements  11),  this  (including  Hz,  of  of  tape  shown  curves  the  played  on  source.  stations  using  previous  source  The  and  data  two  the  further  experimental  levels  data  ( i i i )  The  simultaneous  r e p r o d u c i b i l i t y  period;  the  results  transmission  for  part  survey.  the  type  as  within  current  From  surveys,  data  the  included  survey  good  of  impetus  signal  1979  and  following  the  stations  signal  the  encouraging  subject  before.  by  station  three  The  in  survey  work  1980  5L82.  thesis.  A the  km  therefore with  p a r t i c u l a r  the  the base  frequency,  51  Fig.  5.1  Location of mobile receiver stations area.  within  survey i  52  Fig.  5.2  R e s u l t s of t h r e e s u r v e y s (1979, 80, 81) t o show 1/r dependance of total field strength and r e p r o d u c i b i l i t y of r e s u l t s .  53  increasing  the  of  i n which t h e  analysis  vertical  component  simultaneous that  of t h e measurements. I t i s t h i s mobile  base s t a t i o n  fact  that  caused  by  the  5L82.  with  closely  the  test  in  the c u r r e n t  i n 5L82. To a c c o m p l i s h  current  at  field  MDN  base  station  neutral AF  c u r r e n t data  data  (figure  AF d a t a  recorded 4.4(b)).  representations  (figure  The n e u t r a l c u r r e n t d a t a  180  Hz  neutral  signal  recorded  component  value  on t a p e  station in  clearly  i s primarily  5L82. The r e l a t i v e  that  ensure  neutral  purposes,  v a r i a t i o n s of  with  the  the induced  AF s i g n a l effect  amplitudes  of  relative  data  spectral  5.3(b)  t h e AF  t o a 180 Hz  comparison can  of the  be  made,  r e c e i v e d a t t h e base  stronger  current  .components  (60 Hz, 180 Hz, 300 Hz, and 420 Hz) o f t h e two s e t s o f d a t a a  distinct  correlation.  The o t h e r  and  so t h a t t h e  of t h e " n e u t r a l " the  5.3(a)  current  Similarly,  signals  with  5.4(a) i s a l s o  in figures  1.0.  the  Meridian  relative  way a r e l a t i v e two  of  Figure  h a s been n o r m a l i z e d is  time  simultaneously  h a s been n o r m a l i z e d  of 1.0. In t h i s  shows  by t i m e  and f i g u r e  with  magnitudes of the harmonics of the which  to  simultaneously  component  ( i n which  measurements  are presented  5.4(b).  current  done  a t the base s t a t i o n .  comparison  of t h e d a t a  the data  field.  f i e l d are  made  simultaneously For  frequency)  of the p r i m a r y  this,  4.3(b)),  by t h e  strongly  a r e caused  recorded  the  line)  was  were  measurements o f t h e AF s i g n a l is  same  transmission  variations  neutral  i s divided  the  fits  variations  further  the t o t a l  (at  method of  dependance of the p r i m a r y  spatial  A  measurement  frequency  measurement  t h a t a 1/r c u r v e  baseline coincides  suggests  receiver  at a particular  h e l p s e l i m i n a t e the time The  the  accuracy  show  f r e q u e n c i e s , much s m a l l e r i n  54  amplitude,  are  more  c o r r e l a t i o n .  As  component  not  120  Hz  at  the  fact  and  f i r s t  was  120  that  v a l i d i t y  of  Hz  the  measured the  to  be  between  spectra  360  Hz  neutral  event  -  figure  (figure of  phases  and AF  AF  which  the  AF s i g n a l measured  signals  try  at  here  correlation  of  supportive  of  only  of  source  (obviously be  station  the  of to  general  the the  negligible  the  the  data,  survey  seen  in  is  neutral  current  in  the  a  GIC  to  the  saying the  the  current  change (due  station  AF  signal  the  sum  AF  not,  not  survey  area  however.  It  show  of  origin  the  three  of  at  ensure  that  would  be  signal)  that  the  current  f i e l d  emmissions; be  in  the  time  strongly  5L82  in  two tests  and  are  the  the  two  relation  AF  any  highly  of  the  and  MDN  show  correlation  1/r  would  signal  would  however  AF magnetic  natural  does  area;  hypothesis  if  on  s i m i l a r i t i e s  MDN  for  station  current  and,  doubt  5L82.  base  primary  the  to  current  neutral  support  (determination  neutral  is  from  some  the  at  expected  phase  to  Hz The  addition  Hz  note  120  signals.  in  120  experimentally  the  ignoring  data).  in  throughout  throughout  discussed  base  be  non-zero sheds  effect  strong  the  a  signals,  same  two  would  less  the  the  component  between  correlation to  is  current)  of  two  The  at  correlation  impractical  the  is  show  4.2,  This,  A-phase,  addition  current  The  same  would  of  signal  (neutral  signal  in  4.3(b)).  5.3(a)),  the  in  the  than  component.  measurements  However,  between  component  small  hence  section  smaller  neutral Hz  noise, in  well  much  120  component. the  is  by  stated  correlate  AF component  looking the  does  affected  is  the  survey  area  presumably  these  seen  in  the  base  6C  Hz  ~  ~ -50 120 Hz  1|!f!;  180 Hz  : :\ ±';ir^ :,ti  :::  240 Hz  - 13  300 Hz 360 Hz 420 Hz 480 Hz 540 Hz  I  iT|iim]i'i"':n:'i I  i  :n  - u' i n i r n' J n n n 11 r mjn i' i in  —  "I'mwi  tmm  m mmm  mmm  w <j  600 Hz  5  660 Hz  5 -i  iI  !•  i. ;! :!  ;  •: ;  ?2:00  UT  14:00 Lf  3-381  F i g . 5.3(a) AF-measurements a t base s t a t i o n (3 March 1981). Compare w i t h f i g u r e 4 . 3 ( b ) . On t h e v e r t i c a l s c a l e , two d i v i s i o n s c o r r e s p o n d t o a f a c t o r t e n i n magnetic field.  oi  56  X  X  X  X  o  o —  o »  o N  X  X  X  X  X  X  o . n  o  o  o  g  o in  n  «  ^  X  to  o io  HARMONIC FREQUENCY  F i g . 5.3(b) S p e c t r a l representation of simultaneous neutral current signal ( t o p ) and base s t a t i o n AF s i g n a l (bottom) (3/3/81).  a) AF-measurements at base station (11 J u n e 1981) Compare with f i g u r e 4 . 4 ( b ) . On t h e v e r t i c a l s c a l e * two d i v i s i o n s c o r r e s p o n d t o a f a c t o r t e n i n m a g n e t i c f i e l d . The o r i g i n o f t h e i n c r e a s e d noise in these t r a c e s i s unknown.  OB  to  X  X  X  X  X  X  X  X  X  X  r  o CO  o fM  O CO  9  o  o  o fM  o  3  o  a (O CO  to o ro ro rsi HARMONIC FREQUENCY  i  o  CO  in  10  HARMONIC FREQUENCY  F i g . 5.4(b) S p e c t r a l r e p r e s e n t a t i o n of simultaneous neutral current signal (top) and base s t a t i o n AF s i g n a l (bottom) ( 1 1 / 6 / 8 1 ) .  59 The base s t a t i o n f o r the EM survey i s the same as that in the study of harmonic  c u r r e n t s and GIC i n  used  transmission  line  5L82 (chapters 3 and 4 ) , l o c a t e d 350 m from 5L82. The designs of the  base  station  receiver  and  mobile  s i m i l a r , c o n s i s t i n g of a loop antenna which  i s connected  ( r a d i o s t a t i o n WWV) tape  recorder,  recorder  to  a  DR  station  f o l l o w e d by  an  amplifier  tape r e c o r d e r . Time i n f o r m a t i o n  i s recorded a u d i b l y on  and  receiver are  the  mobile  through FM p u l s e s on the base s t a t i o n  (from r a d i o s t a t i o n WWVB). In a d d i t i o n , as i n  surveys,  a  station  magnetometer  tape  most  was used to monitor geomagnetic  EM  field  condit ions. As  discussed  receiver  system  previously  was  ( i n s e c t i o n 3.3),  calibrated  s i n u s o i d a l l y varying  magnetic  by  placing  field  of  frequency, and r e c o r d i n g the subsequent (see  Appendix  B  mobile  the antenna  in a  magnitude  and  known  amplified  s i g n a l on tape  f o r a schematic diagram of the apparatus and a  d e t a i l e d d i s c u s s i o n of calibration  the  signal  is  calibration then  played  procedures).  The  recorded  back through the spectrum  a n a l y z e r i n the same manner the f i e l d data i s a n a l y z e d . Thus the recorded s i g n a l strength/magnetic f i e l d magnitude known  as  a  function  of  frequency  relation  over the band of i n t e r e s t  (60 Hz - 1 KHz). S p e c t r a l a n a l y s i s of both the mobile s t a t i o n data c o n s i s t s of feeding the s i g n a l spectrum  analyzer,  is  and  base  i n t o an a n a l o g - i n p u t  on which the c o n t r o l s a r e s e t to sample the  s i g n a l 64 times, which takes the spectrum a n a l y z e r  18  Therefore  16 c y c l e s of  the  each  fundamental  samples  sample  i s 0.281 seconds, or about  frequency, and the spectrum  of  64  seconds.  consecutive  i s averaged t o g i v e the f i n a l output. T h i s a n a l y s i s i s  60 applied the  to  both  same 18  mobile  5.3  second  station,  primary  mobile  taking  a  As  more in  base s t a t i o n  data  for  value  for  each  account  time  variation  of  the  Survey results  of  survey  the  s u r v e y s done  using  i n 1979  and  as  a source  was  signal  recorded  at  5L82  1981.  stated  i n the p r e v i o u s s e c t i o n , was  a n a l y z e r . The  played  back  in  the  of  5L82, were u s e d  the  the  four strongest frequency  to  to  into  extensive  station  l a b through  components,  f o u r s t r o n g e s t h a r m o n i c c u r r e n t components  Hz,  shown  1981  t h e b a s i s of t h e  completed  (180  and  field.  On  each  data  p e r i o d to give a time-averaged  R e s u l t s of the  1980,  station  300  Hz,  i n the 420  Hz)  interpretation. p l u s the  i n p r e v i o u s c h a p t e r s t o be  The  fundamental  the  a  spectrum  corresponding i n the  three (60 Hz)  neutral  harmonics have  been  s t r o n g e s t and  most  stable  r e p r e s e n t s the  ratio  of  use. For  each  vertical  frequency,  component a t e a c h  component  station  to the  the  base  station.  The  measurement a t t h e  base  station  equals  station  at  the data  also  s e r v e d as one  resultant  data  Concerning  the  should  be  noted:  is data  shown  of  data  the m o b i l e  in  presented  figures in  simultaneous  vertical  i s normalized 1.0  (note  receiver  so  the  stations).  5 . 5 ( a ) , ( b ) , ( c ) , and  figure  5.5,  the  the  the base The (d).  following  61  (a) The a r e a r e p r e s e n t e d by e a c h f i g u r e i s t h e same as t h a t i n f i g u r e 5.1, and has been r e f e r r e d t o i n t h i s work as the "survey a r e a . " (b) The l o c a t i o n of m o b i l e r e c e i v e r s t a t i o n s i s l a r g e l y due to accessibility in the mountainous t e r r a i n of t h e survey area. Regions with few or no measurements indicate an i n a c c e s s i b l e a r e a . B a s e d on t h e r e s u l t s of t h e s m a l l e r s c a l e s u r v e y done i n 1980, t h e density of stations was i n c r e a s e d i n t h e J a c o b s L a k e a r e a and i n the r e g i o n near A l o u e t t e Lake. (c)  A  A n t i c i p a t i n g t h e 1/r r e l a t i o n shown in the 1979 1980 d a t a , t h e c o n t o u r s a r e s p a c e d a t i n t e r v a l s of n an i n t e g e r from 2 t o 50.  detailed  determined  5.4  determining  To  and  the c o n f i d e n c e  using  i n Appendix  C.  analysis  the  approach  further  any  unexplained  on  the d a t a ,  t h e B i o t - S a v a r t law free  space.  The  elements simulates  the  integer),  with  alone.  field  finite-length the  t o about  30  current  finite-length  km  r e p r e s e n t s the  survey  contours  set  the v a l u e  of  are  The  consists  transmission line  and  The  calculated  l a y o u t of  base s t a t i o n ) ,  work.  the  of  s u b s t a t i o n i n t h e west 5.6  is  i s presented  geometry  (from M e r i d i a n  figure  5.6  reference  f o r summing  consists  results.  to the c u r r e n t source  to o b t a i n i n g the  current  (n an  was  d e s c r i b i n g known  figure  reference f i e l d due  in  1/n  the data  data  results,  The  elements  of  the  component  the e x p e r i m e n t a l  in which  of  known e f f e c t s  field  theoretical of  interpretive  "reference f i e l d . "  vertical  t h e manner  i s given  investigating  study  of  Interpretation  b a s i s of an  effects,  as a  contoured  A n a l y s i s and The  of  and  description  and 1/n,  to  5L82  e a s t of area  used  values  the p o i n t c o r r e s p o n d i n g  the in of to  62 the base s t a t i o n normalized to 1.0 is  presented  in  interpretation). represents  the  the  Thus  same  the  (that  i s , the r e f e r e n c e  manner  reference  normalized primary  as  the  field  field  data  field  to  presented  aid here  i n the survey area  due  to t r a n s m i s s i o n l i n e 5L82. From the data presented general t r e n d  of  the  in f i g u r e  contours  However,  is  5.5,  i t i s c l e a r t h a t the  similar  to  that  of  aspects of the data which cannot  the  reference  field.  attributed  to the geomenty of 5L82 are seen as i r r e g u l a r i t i e s i n  the contours of the data, and e x i s t  in  three  regions  survey a r e a :  (a) The A l o u e t t e Lake r e g i o n ; (b) The  Jacobs Lake r e g i o n ;  (c) The  northwestern  p a r t of the survey a r e a .  in  be  the  63  F i g . 5.5(a) EM survey c o n t o u r e d d a t a - 60  Hz.  64  65  F i g . 5.5(c) EM survey contoured data - 300 Hz.  F i g . 5.5(d) EM survey c o n t o u r e d d a t a - 420  Hz.  67  68 The total  data  f i e l d  regions  d i f f e r s  just  survey.  c l e a r l y  The  from  mentioned,  effects  combination  of  shown  the  a l l  in  secondary structures  The  effect  of  in  the  general  of  the  must  examined.  other  power  lines  run  5L82;  a  the  eastern  line  within a  small  survey  about  16  line found  survey  area  is  that  perpendicular  5L82  has of  three  used  in  the  of  a  was  only  distance  and the to  signal  would  the  figure  set  of  200  A  shows 60  KV  south  of  edge 10  the  km  edge,  near the  of  only  southwestern  m.  its  Substation,  about  from  3.1  the  western  camp  the  of  three  to  f i n a l l y  a  in  because  km  be  measurements  but  3  to  following  lines  distinguishable of  shown  as  f i e l d  exists  power  conductive  Meridian  from  along  A  about  line  the  l i n e ,  not  observed  data,  power  have  the  been  chosen  from km  which  the  the  total  region.  area;  supplying  area  to  5L82,  d i r e c t i o n  the  survey  a  data  due  was  the  edge  within  to  in  North-South  work  signal  the  other  than  another  local  the  result  determining  the  northward  5L82,  Experimental the  exist  runs  of  of  area  other  East-West  the  the  transmission  survey  in  to  are  contours  influencing  sources  an  and  of  the  the  do  line  area;  of  lines  perpendicular survey  The  on  effects earth.  p o s s i b i l i t y  systematically  from  effects  geometry  trend  region  isolation  in  frequencies  data  measuring  f i e l d of the  configuration  be  f i e l d  measured  following:  (c)  However  four  the  random e r r o r total f i e l d ;  expected.  experimentally  for  (b)  the  the  reference  possible systematic been determined;  the  that  the  (a)  produce  is  shows  the from  power and  Loon  Lake.  local  line  from  mobile  the  5L82  receiver  69 station but  was  the  closest 750  m  well  data  from  other  the  local  unlikely  general  area that  cannot the  survey area are  in  the  region.  data  follows  that  5L82  the  not  fact  due  to  sole  In  the  is  The  about  of  fits  the  three  to  the  known what power primary  by  the  the  case.  reference  interest  reference of  one  However  produced  systematic  field it  i n the  general  trend  field  of  lines of  strongly  primary  most  data  power  or  within  is  other  field  elevation,  the  receiving in  angle  example,  if a  cosine  i n the  transmission  the  cosine  the  implies  within  is  factor  i t was  1 km  5L82 and  would be plane,  built.  As  That  m a g n i t u d e of  factor  is  the  exhibited  antenna  line.  from the  is,  and from the  the  This  is  if  the  the  by  mobile  follows  stated  the  direction  5L82,  the  of  vertical  of  and  the  station  is  0.995. In a d d i t i o n , but  may  elevation  i s determined  horizontal  between  in a h o r i z o n t a l  t e r r a i n upon w h i c h  error.  the  error the  data  receiver  station differs  station  100  lie  or  between  elevation  not  the  The  in  then  of  determining  i s introduced. the  error  horizontally-placed  difference  the  within  the  fact that  i n any  line,  from t h i s s t a t i o n  calculated.  fields  power  obtained  i t i s not  e f f e c t on  source  plane  error  of  5L82. F o r  the  the an  of  an  component  does  data  i s not  region,  local  discarded  previously.  i s , the  s o u r c e of  in  elevation  m,  the  and  be  shown by  the  that  essentially  cosine  from t h e  area.  be  5L82,  m  l o c a l i z e d r e g i o n s of  That  that is  Another by  and  trend  l i n e s i n the  the  survey  line,  i s c a r r i e d , hence the  survey  200  from w h i c h d a t a was  interest discussed  power  current  station  the  within  a point  from t h i s s t a t i o n was  receiver  r e g i o n s of  the  employed a t  5L82  relief  previously,  of the  70 data  suggests  here  are  essentially  experiment. possible lines  close  factor  negligible  refine  to  field  technique. variations  the  proposed  The  indicate  error  main  receiver  source used  signals  audio-frequency a  acceptable smallest).  of  and  t a p e . The  The  of  range  However a m p l i t u d e to l e s s  signal.  each  Since  reading divided error),  station  about  by a  than  data  the  maximum  other  power  or  total  the  systematic the  cosine  determining  current show  a of  element  that  interest  are  the not  interpretation.  The  of  and  random e r r o r ,  33  signals with  and used dB  (60  dB,  station  were r e c o r d e d  fall  within  an  300  Hz  largest,  about  determined  ±5%  the m o b i l e (each  of ±10%  p o i n t , u s i n g t h e method of T o p p i n g  on  amplitude  is limited,  of  mobile  imperfect  reading  random e r r o r  Both  in  recording  Hz  or  lies  direct  here  reproduction ±0.5  experiment  the d a t a .  point consists  base  clearly  configuration  to  in this  analyze  four frequencies  range  the  main p r o b l e m s  voltage  by  finite  sources  random e r r o r  base  experimentally,  each data  and  the  errors.  t o r e c o r d and  limited  reproduction.  itself,  r e g i o n s of  involved in  these  of  of  is  including  i n the  three  p o i n t out  it  A l s o , the o t h e r by  presented  accuracy  three-dimensional  i n the  t h e m a g n i t u d e of  the apparatus  line).  line  p r e v i o u s d i s c u s s i o n i s meant  discussion will  The  i n the  i n t o account  i n the data  the data  the e f f e c t  measurements,  i n which the  i s taken  on  method,  i n t o account  station  to a systematic  following  other  taken  mobile  source  random  the  effects  to w i t h i n the  the c u r r e n t  c o u l d be  in  reference  are  systematic  to e x p e r i m e n t a l l y determine  procedures  due  To  (by m e a s u r i n g  field  the  t h a t the  of  receiver with  i s assigned  (1966, p.  the  17)  ±5% to for  71  error  estimation: e =mobile r e c e i v e r  error  m  €. =base s t a t i o n  error  D  € =maximum random e r r o r f o r each data p o i n t =  le  1  The the  error  mobile For  that  receiver  further  could the  system  which  gives  results would the  a digital  by be  confidence commercial To a  of  against  the  shown  plotted scale the  to  of  the  the  geophysical  two  ±10%  in  be  FM  line  recording  the  survey  This  data  device  would  specific the  Also,  In  of  the  addition,  it  measurements  again  during  arranged  in  each to  a  frequencies  confidence  lines  once  source),  the  measurements.  some f i e l d  traversed  in  a  direction  increase  i s , i n f a c t , common  the  i n some  surveys. random e r r o r  the  5.7.  in figures  figures  of  c a l i b r a t i o n of  recording  random e r r o r .  i s , certain  from  figure  i n the  increase  repeat  show t h e  distance  error  would  p r o f i l e s were t a k e n ,  linearly in  amplitude  results.  graphically  set  are  could  10%  B.  amplitude  associated  that  pattern  (perpendicular  the  f e a s i b l e to  same s u r v e y ;  grid  the  readout  decreasing most  i n Appendix  i m p r o v e d . An  of  detects  I =  i t i s t h i s method of  greatly  accuracy  le  shown g r a p h i c a l l y  system,  work,  be  improve  and  is also  I +  with  the  two  5.9(b) the  5.9(a),  (with  data  i n the  data  is  profile  amplitude-distance  5 . 8 ( a ) and  5.8(b) and  associated  i n which  s o u r c e . The  The  involved  and  error  points).  data, plotted  locations  relations on  bars  a  are  log-log  indicating  72  F i g . 5.7  P r o f i l e l o c a t i o n s . D i s t a n c e s are d e t e r m i n e d from the p r o f i l e - b a s e l i n e i n t e r s e c t i o n and a r e marked a l o n g the respective p r o f i l e i n 1 km intervals. The baseline i s equivalent t o the transmission line (5L82) s o u r c e .  74  0 01 4 01  1 11 1 1 1T 'I 10  1 1 . 1 1 I.I.—l 10  - -• t ' ;i  DISTANCE FROM SOURCE (km)  F i g ,  5.8(b)  P r o f i l e d  data  -  Section  A-B.  ,  io Ol STANCE FROM SOURCE (km)  i ,—  76  DISTANCE FROM SOURCE (km)  DISTANCE FROM SOURCE (km)  DISTANCE FROM SOURCE (km)  '  F i g . 5.9(b) P r o f i l e d data - S e c t i o n C-D.  DISTANCE FROM SOURCE (km)  77 The show  intent  the  of  effect  of  presenting  the  secondary  total  f i e l d .  In  a  three  regions  of  interest,  and  stated  course, baseline Figure  5.8(b)  Note  plot  as  a  (300  Hz  that  in  distances (figures  420  geologic  found  explorat  d i o r i t e survey  is  km is  the  of  a  the  higher  deviation  the  the  the  w i l l  detailed  proposed  EM  a  method  of of  log-log  an  inverse  area  region,  error give  C-D  1/r the  possible  any  detailed would  the  (at  and  of  a  anomalies  survey  is  error  theoretical  However  geophysical  1/r  P r o f i l e  Lake  random  data.  area.  frequencies  from  given  chapter  given  on  of the  the  source).  the  data,  deviation  survey  Alouette  from  maps  from  by  The  from  data  survey  this  graphed  of  this  of  well-defined the  -1.  shows  theoretical  shown  associated of  definitions  the  is  part  in  deviation  remainder  with  regions  only of  reconnaissance  ion.  Geologic region  6  beyond  or with  slope  data  extends  though  relation  the  the  better  v e r t i c a l  p r o f i l e  of  (as  greater  5.9(b))  interpretation  about  interest  and  The  information come  than  A-B  from  error  to  measured  The  edge  region,  northwestern  well  apparatus.  with show  significant  r e l a t i o n ,  random  line  greater  a  the  is  contoured  section.  to  Lake  p r o f i l e  the  the  P r o f i l e  inverse  Hz)  the  5.9(a)  by an  straight and  relation  for  in  in  deviation  Jacobs  accounted  bars).  shows  the  seen  effects.  slight  in  interpretation,  this  northward  shows  in  in  same  (5L82)  relation nearly  the  as  data  f i e l d  reconnaissance  previously  show  the  information  given  in  figure  and  d i o r i t e  are  area.  However,  late  of 5.10. the  the  survey  Granite, main  area  surrounding  granodiorite,  geologic  (Quaternary  and  quartz  constituents  period)  g l a c i a l  of  the  deposits  78 are  also  shown,  discussed  region  survey  extending Jacobs  in  East-West  of  area a  With  no  conductivity  exists  data  deposits. to  suggests  conductivity result,  deposits.  band  than  knowing  5.11  g l a c i a l  fact  conductors,  needed  determine  results  of  this  information geologic However,  the  f e a s i b i l i t y source; Forest  of  the and  scope  Alouette  use  geologic area  amplitude  of  rocks.  of  in  the  an  rocks  a  are  within  g l a c i a l  this  study be  of left  plausible  is  for  a  would  be The  surveys  of and  material.  to  lines  the  poor  package  deposit  thesis  transmission  a  the  e l e c t r i c a l  values.  of  the  was  extremely  geophysical  of  in very  other  the  region,  information  well  and  signal  conductivity  sit  be  e l e c t r i c a l  Lake  is  only  rocks  higher  This  additional  w i l l  south  in  igneous  granitic  of  of  deposit  can  contrast  much  objective  Lake  it  are  testing  just  background  quantitative  the  detailed  region,  deposits  perhaps  a  an  Lake. the  would  section  cross-section  Alouette  however  and and  ending  as  within  with  the  that  is  northern  within  thesis  including  sampling  the  background  e l e c t r i c a l to  of  interest  area  geologic  Jacobs  the  smaller  the  a  of  feature,  significant  between  the  The  southward,  knowledge a  regions Lake  this  is  Since  be the  shows  through  further that  determined  g l a c i a l  Figure  hypothesized  the  Alouette  also  direction  with  The  narrow  Lake.  g l a c i a l  correlate  previously.  extensive the  and  show as  an  the EM  U.B.C.  Research  future  project.  79  QUATCKNAaV  C O A S T PLUTONIC R O C K S GARIBALDI GROUP i  1-A  •,bi  a  conyian—tf.  mm.nj» «nrf  co*  jg§3  CKCTACIOOS  I  ~  i;  1  ,t>2  b  3  •  1  I  E l ELI  1 MRM FORMATION:  S3  JUMASCIC « N 0 C N C T M I O U S LOWM citmciau* GAMBIfR CROUP' mil meat, J ^ D I W M  LT3: JURASSIC  HARRISON LAKE fORMATION:  rai-JUMtSMC  ISLANO GROUP:  Fig.  5.10  Geologic  map  of survey  area.  E£l  Fig.  5.10  Continued 1153A) .  (from  Geological  Survey  of  Canada  Map  Fig.  5.11  Geologic region.  cross-section  (E-W)  through  Jacobs  Lake  82 Chapter  VI  CONCLUSION  The  conclusion  of  objectives. Obviously, exploration  method  practicability carry to  this  the  had  nature to  be  o f t h e method,  out the experiment  thesis of  must the  well  effect t o be  be s u r v e y e d  i n ' terms  of  tested  to  reconnaissance Chapter  prove  the  EM the  capability  to  m e a s u r e m e n t s , had  of a r e g i o n which  because  i t would  could  have  an  o f t h e method. F i n a l l y ,  t h e method had  it  an  described  s y s t e m s and t r a n s m i s s i o n method  Chapter  Three,  fourth  chapter  dealing  with  in Meridian  of  its  to  be  useful  as  economical  method o f g e o p h y s i c a l e x p l o r a t i o n . Two  experimental  important,  with  Secondly,  the  and o b t a i n m e a n i n g f u l  was  on t h e e f f i c i e n c y  source  studied.  be known. In a d d i t i o n , t h e d i m e n s i o n  reasonably  begin  in  lines  detail  as  t h e o p e r a t i o n o f power  relates  to  o f o b t a i n i n g measurements was  including detailed  the c u r r e n t s  instrumentation the  results  of  and  line  practicability  test  t h e u s e f u l n e s s of t h e method, were g i v e n  The  results  The  and e x p e r i m e n t s  surveys,  t h e method, and an e x t e n s i v e  indicate  The  described in  5L82 and  o f two t e s t  the  work.  calibration.  of t e s t s  in transmission  s u b s t a t i o n . The r e s u l t s  clearly  this  in  systems t o show  survey,  Chapter  t h a t t h e method o f an EM  to  Five. survey  83 using  a  high-voltage  p r a c t i c a l proper  and  useful,  conditions  of  the  120  km  area  non-uniform minimal  be  of  of  ideas  interest.  An would  this  chapter  improvement be  process  to  as  as  electromagnetic in  exploration thesis,  the  secondary better  geophysics,  known  very  f a l l s  a  expected  as  in  of  figure  was  the  over  3  far the  the 6.1  to  and  source of  the  and  table  surveyed  concluding other  design.  one  the 6.1:  One  the  source, The  and  1/r  while 3  not  the  that  of  earth  of  1/r  and with in  boundary. of  that  total  f i e l d  f a l l o f f  depends  the  in  encompass  includes  the  is  this  deals  results  relation  frequency  of  e a r l i e r  1950) and  a  study  free-space  space-earth  is  the  d i r e c t i o n  of  the  of  application  d i d  and  proposed  the  the  a  the  works  The  by  earth,  of  using  as  with  a  (with  remarks,  related  (Price,  near  location  understanding  s i m p l i f i e d  uniform  source.  ground  was  expressed  EM e x p l o r a t i o n ,  from  efficiency,  pertinent  earth.  and  of  exploration  subject  a  understood  terms  experimental  as  both  the  interaction  has  the  consequence  nearer  conductivity seen  1/r  their  be  personnel-days,  with  of  conductive  current  respect  deal  model,  on  fields  line  with off  a  works  important  paper,  of  three  continue  and  calculations,  In  experimental  to  theoretical  electromagnetic  A  Due  in  are  can  of  theoretical  and  source  s u i t a b i l i t y  met.  method  the  fields  effects  particular  the  a  t e r r a i n  To  improving  work.  Biot-Savart  are  w i l l  increase  well  extensive  in  as  limitations the  however)  equipment.  remainder of  notably  mountainous  of  line  its  surveyed)  coverage,  amount  if  (most  to  area  2  transmission  on  source,  is the as  CONSIDER A PERIODIC LINE CURRENT cccos ut  IN THE  x- DIRECTION ALONG THE LINE y=0,z = h (Price's notation): •line current cccosut (§1^)  z  free space semi-infinite conductor  THE DIRECT FIELD OF THE LINEAR CURRENT CAN BE EXPRESSED IN THE FORM: HyiH =  2=*£PSHt h-iy  I  SIMILAR ARE  ,  0 fZ  =  Q  IN FORM. THE COMPONENTS OF THE INDUCED FIELD  GIVEN IN THE FOLLOWING  EXPANSION:  Hy .iH, = 2c.acosut (f'-jStC - 3C .15C . 315C . 4  2  6  )} •  S  Q)  • 2c.asinut (4C -£(C .3C .15C - 315C ... )) 3  2  4  6  8  [equation 10.7 in Price (1950)] VALID TO THREE SIGNIFICANT FIGURES  IF K|S6  WHERE: C  s  ah • iay o= 2  4na  y  0= conductivity  (sec ) 1  ^magnetic permeability (assumed to beD NOTE THAT WHEN a (AND THEREFORE a) TENDS TO INFINITY, TENDS  c.cpsnt n • iy  2  TO  SO  THAT  THE  INDUCED  FIELD  IS  THAT  H  • iHj  y  O F  A  CURRENT. EQUAL AND OPPOSITE TO THE INDUCING CURRENT, ALONG THE LINE y*O.Z=-h.  IN AGREEMENT WITH IMAGE THEORY.  IF y IS SUFFICIENTLY LARGE. THEN THE ASSUMPTIONS |C| 5 6 and y» h ARE  BOTH VALID.  IN THIS CASE. . J iay and the induced field (in the vertical direction) becomes;  r  iH = 2c. a cos wt [day) ,—J 1  • 2c, asinuit[C-—; day)3 ]  THE  TOTAL FIELD IN THE z - DIRECTION  THE  DIRECT FIELD [from equation (1)1  FIELD  (3)  IS THE SUM OF  AND  THE INDUCED  [equation (3) ], IN WHICH THE COSINE  TERMS  CANCEL: H (total field) = 2c.sinut • - U a* y  <> 4  z  EQUATION (4) SHOWS EXPLICITLY  J  THE "1/r " NATURE  OF THE TOTAL FIELD FOR SUFFICIENTLY  F i g . 6.1  3  LARGE " r "  V e r t i c a l Induced F i e l d ( H ) c a l c u l a t i o n s , z  85  TABLE 6.1 Resistivity (nm)  Rock Type  10  Granite  f  s  TO  4  3X10  2  10  Soil Waters  900  Natural Waters  300  o =8rr cr f/c (cnT ) cr=conductivity (sec' ) »i=magnetic p e r m e a b i l i t y f = f r e q u e n c y (Hz) h<20 m 2  2  2  o  (Hz)  (cm  - 1  6/c  )  (km)  60 180 300 420  2.18X10' 3.78X10" 4.87X10" 5.76x10"  60 180 300 420  2.18x10* 3.77x10" 4.87x10" 5.76X10'  60 180 300 420  1.26xl0' 2.18x102.81X10" 3.32X10"  60 180 300 420  2.18X10" 3.77x104.87xl0" 5.76X10"  60 180 300 420  7.26X10" 1.26x10" * 1.62x10' 1.92X10-  0.83 0.48 0.37 0.31  60 . 180 300 420  1.26xl0* 2.18x10" 2.81x10-" 3.32x10"  0.48 0.28 0.21 0.18  270 160 120 100  7 7 7 7  28 1 6 12 10  6 6 6  6  4.8 2.7 2.1 1 .8  5  5  5 5  2.8 1 .6 1 .2 1 .0  5 5 5  5  5  4  4  4  4  4  2  w  1  (assumed  t o be  1)  T a b l e 6.1 Determining 6/o (minimum d i s t a n c e from l i n e source f o r w h i c h oy>6 and y>>h), which corresponds to a total f i e l d - distance relation of 1/r ( s e e f i g u r e 6 . 1 ) . Rock t y p e r e s i s t i v i t y r a n g e from T e l f o r d (1976, p . 4 5 2 - 4 5 4 ) . The d i s t a n c e from t h e l i n e s o u r c e t o t h e g r o u n d , h, i s l e s s t h a n 20 m. 3  From possible the  field  the  results  of  to explain certain experiment.  the  preceeding  aspects  of the  In t h e n o r t h e r n  region  discussion data  i t  is  obtained  from  of the survey  area,  86  the  data  greater  shows  rate  p r o f i l e  the  is  of  signal  f i e l d and  it  is  frequency  affected  nearer  effect  strength, it  does  both  the  of  that  of  table  those  presented in  the  q u a l i t a t i v e l y geologic the  The varied  in  data  component  make was  it  which  in  the  within  measured  it  at  seems  f i e l d  survey  clear  f i e l d  upon  underlying (last  typical  that  are  and  to  patterns  previously)  effects,  area  are  However  effect  distances  length  secondary  that  represented  are the by  data.  method  more  total  data.  into  3  example  the  Thus  the  the  an  of  comes  1/r  frequencies as  an the  the  conductivity it  Hz)  not  dependant  data.  within  is  In is  420  is  the  (discussed  experimental to  the  and  which  v e r t i c a l of  data.  However,  intended  the  model,  f a l l o f f  widely  by  is  on  f i e l d  vary  explained  seen  6.1  reference  which  at  higher  on  f a l l o f f  Hz  source.  interpretation  and  at  Hz),  distance  f i e l d  total  (300  and  effect  the  increased  a  the  the  in  at  that  source  seen  primary  Table  fact  length  180  off data  greater  used  which  the  However  the  and  may  differences  patterns  (in  3  Hz  is  as  that  the  geologic  6.1)  f i n i t e  the  secondary  distance  the  (60  source).  1/r  source.  f a l l s  contoured  have  the  note  affect  the  would  patterns  of  effect  a  the  frequencies  length  frequency  column  seen  the  higher  the  as  The  on  to  signal  explanation  from  frequencies  the  f i e l d  both  which  based  does  source  materials.  is  into  riot  show  away  the  used comes  the  length,  f i n i t e  relation  of  possible  important  in  the  seen  exhibit  lower  of  in  One  not  the  effect  (as  5.6)  apparent  than  1/r  further  does  more  total  f i n i t e  (figure  addition,  v e r t i c a l  than  data).  source  the  u t i l i z e d  effective. in  the  The  in  this  thesis  amplitude  present  of  the  experiment;  could  be  v e r t i c a l however,  87  horizontal  components  orientation smaller  of  the  could  receiver  coil.  line  susceptible component direct  to  of  natural  the  source  o(Aboul-Atta  et  exploration, searching  current  magnetic  a l . , 1981).  including  due  to  geothermal  waters.  s y s t e m as  magnetic  field  calibrated  with  the  W i t h a more a d v a n c e d current  strengths  quantitative determined. measure  In  line  the  measure  of  present  currents  utilized neutral  are  of  the  given  here  current  field  time  of  absolute  magnetic for  information  known  the  that  EM  valuable  in ore  mineral-laden  for  absolute was  strength  (Appendix  C).  knowledge o f  not  with  for  neutral  measurements,  was  values  field  from  advantage  structures  completeness, i s not  used  survey  it  more  conductive of  a  receiver  conductivity survey,  to  mobile  and  concurrently  m e a s u r e m e n t s . However, t h e station)  the  is  as  be  theoretical basis, at  the  well  be  much  horizontal  noted  method,  since  to magnetic  the  certain  be  also  to  isolated  in c o n d u c t i v i t y  can  measurements,  a  should  l o c a t i o n s as  i t stands  respect  is  proper  respect  expected  is totally  proposed  increase  (with  However,  which  It  the  for geothermal  deposits,  The  induction  by  components a r e  would be  noise.  contribution,  measured  components  s o u r c e ) and signal  be  Horizontal  i n magnitude than v e r t i c a l  horizontal  base  easily  could  feasible  mobile  four  though  (see  table  be to  receiver  (as m e a s u r e d the  a  at  the  frequencies simultaneous 6.2):  88 TABLE  6.2 Amplitude of Magnetic F i e l d (nT(rms))  Frequency 60 180 300 420  Hz Hz Hz Hz  50 3.6 0.16 0.67  T a b l e 6.2 Magnetic field (15:50 L T , 2 2 / 7 / 8 1 ) . N o t e :  The  receiver  modified  to obtain  information systems Dr.  system  is  phase  to study  a receiver  (Frydecky,1980)  which  capabilities represented  by  information It  was  is  during  the  signal.  Phase  interpretation  Currently  underway  (U.B.C.)  harmonic  notched  previously was  field,  by  with  in  i s a study  term,  in  the  60 Hz  f o r which  extremely  Each  high-Q  harmonic  so t h a t  section  survey  activity  relative  3.2(g)  during  is phase  data  that  the  d a t a ) . With  affecting  recording  field  The  is available.  C for this  station.  levels.  filter.  monitored  the  of geomagnetic  geomagnetic  have t o be  i s used as a r e f e r e n c e  adaptive  (see Appendix  receiver  the  group  s i n e and c o s i n e  accomplished  each mobile that  a  noted  geomagnetic  indications  are  field  measurements  This  i n the f i e l d  the  would  station  i n c o r p o r a t e s an a d a p t i v e f i l t e r t e c h n i q u e  among t h e h a r m o n i c s  geomagnetic  the  of  base  i n many EM  features.  t o measure s i g n a l  harmonics  from  used  instrumentation  component d e t e c t e d subsequent  data  conductive  at  i n the experiment  information  important  R.D. R u s s e l l ' s  using  used  strengths 1r=1 nT.  nT nT nT nT •  can the  EM  the survey  the record  of  be c h e c k e d f o r measurements.  t h e t i m e o f measurement a t  In t h e p r e s e n t work, i t was was q u i e t  t o moderate  t h e measurements, and was n o t a f a c t o r  in  found  in activity  analyzing  the  89 data. the  Of  course  analysis  base  is  the  interest u t i l i z e d  to  reader.  a  the  high-voltage EM was  conductivity  induction  in  (Price,  1950;  has  line  been  the  this  AF  aspect  signal  of  at  the  works  of  to  power  be  Weaver,  pertaining, above  a l . ,  published).  1975;  Also,  is  Luette,  was  in  a  covered  by  used  region  in  GIC)  with  crust  were  to  electromagnetic is  p a r t i c u l a r ,  et  for  a l . ,  on  et  well  represented  1977;  Park,  1977).  of  of  a  1950;  The  1979;  VLF in  fields  systems  a l . ,  stimulated  Much  purpose  1981).  interaction  prevalent  (Price, the  power  obtained.  1973).  to  earth  Hayashi the  e l e c t r i c a l  Weaver,  e x p l i c i t l y  1978b;  radiation  1971;  the  (and  which  conductor  (Aboul-Atta  harmonic  upper  generally  sounding  magnetosphere  (Helliwell,  and  and  et  The  experiment  one-dimensional  lower  1951;  a c t i v i t y  et  and  the  related  line  1979).  1969),  geomagnetic (Hayashi  transmission (Lienert,  source  Spies,  mentioning  semi-infinite  done  studied  the  of  in  controlled-source  pertaining  Gordon,  electromagnetic  a l . ,  DC  of  a  current and  by A  survey  models work  line  c r i t e r i a  monitoring  extensive,  Theoretical  of  continous  concludes  survey  Wait  important  chapter  low-frequency  work  most  station. This  the  the  of  effect has  been  Boteler  transmission emissions  the  in  literature  90 REFERENCES  A b o u l - A t t a , 0., S h a f a i , L., V o h r a , D.R., 'Applicability of the Theory of Infinite Line Current Above L a y e r e d E a r t h f o r E l e c t r o m a g n e t i c Sounding', paper g i v e n at CGU Conference, C a l g a r y , A l b e r t a , May, 1981.  A d k i n s , B., Current 1975.  and H a r l e y , R.G., M a c h i n e s , Chapman  Blume, L . F . , C a m i l l i , G., Transformer Engineering, Y o r k , N.Y.,1938.  The and  General Hall,  Boyajian, John Wiley  T h e o r y of A l t e r n a t i n g Ltd., London, U.K.,  A., and  Montsinger, Sons, Inc.,  B o t e l e r , D.H., 'Hall-Effect Current U.B.C./B.C. H y d r o GIC S t u d y I n t e r n a l R e p o r t ,  V.M., New  Transducers', 1979.  B o t e l e r , D.H., 'The P r o b l e m of S o l a r I n d u c e d Currents', SolarTerrestrial P r e d i c t i o n s Proceedings, R.F. D o n n e l l y , ed., B o u l d e r , C o l o . , V o l . 2, A p r i l 1979, pp. 149-161. B o t e l e r , D.H., Watanabe, T., S h i e r , R.M., and H o r i t a , R.E., 'Characteristics of G e o m a g n e t i c a l l y I n d u c e d C u r r e n t s i n t h e B.C. H y d r o 500 KV S y s t e m , a c c e p t e d f o r p u b l i c a t i o n i n I E E E , Power A p p a r a t u s and S y s t e m s . 1  E a t o n , J.R., E l e c t r i c Power T r a n s m i s s i o n I n c . , E n g l e w o o d C l i f f s , New J e r s e y ,  Systems, 1972.  Prentice-Hall,  Fisher, Arthur, 'Science N e w s f r o n t - From the Sun: O u t a g e s ' , P o p u l a r S c i e n c e , V o l . 218, No. 6, 1981. Frydecky, M.Sc.  Ivan I g o r , 'The Induced t h e s i s , U n i v e r s i t y of B r i t i s h  Power  Polarization Receiver', Columbia, 1980.  G o r d o n , A.N., 'Electromagnetic Induction in a Uniform SemiInfinite Conductor', Q u a r t . J . Mech. A p p l . Math., V o l . 4, P t . 1, 1951, pp. 116-128.  91  Grant, F . S . And West, G . F . , Interpretation Theory in Applied Geophysics, McGraw-Hill Book Company, New Y o r k , N . Y . , 1965.  Hayashi, K . , Oguti, T . , Watanabe, T . , and Zambresky, L.F.,' A b s o l u t e S e n s i t i v i t y of a High-»i M e t a l C o r e S o l e n o i d as a Magnetic Sensor', J . Geomag. Geoelectr., 30, 1978a, pp. 619630.  Hayashi, K . , Oguti, T . , Watanabe, T . , Tsuruda, K . , Kokubun, S., and Horita, R . E . , 'Power Harmonic Radiation Enhancement D u r i n g the Sudden Commencement of a Magnetic Storm', Nature, Vol. 275, 1978b, p p . 627-629.  Hayashi, K . , Oguti, T . , Watanabe, T . , Tsuruda, K . , Kokubun, S., and H o r i t a , R . E . , 'Harmonics of 60 H z in Power Systems Caused by Geomagnetic Disturbances', S o l a r - T e r r e s t r i a l Predictions Proceedings, R . F . Donnelly, ed., Boulder, Colo., Vol. 2, April 1979, pp. 172-181.  Heiland, C . A . , Geophysical New Y o r k , N . Y . , 1940.  Exploration,  Prentice-Hall,  H e l l i w e l l , R . A . , Katsufrakis, J . P . , B e l l , T . F . , Raghram, R . J . , 'VLF Line Radiation in the Magnetosphere and Its Association With Power Radiation', J . Geophys. Res., V o l . 80, No. 31, pp. 4249-4258.  Jackson, J . D . , Classical Inc., New Y o r k , N . Y . ,  Electrodynamics, 1975.  John  Wiley  Inc.,  and Earth's System 1975,  and  Sons,  Lienert, Barry R., 'Crustal E l e c t r i c a l Conductivities Along Eastern Flank of the Sierra Nevadas', Geophysics, V o l . No. 11, 1979, pp. 1830-1845.  the 44,  Luette,' J . P . , Park, C . G . , and H e l l i w e l l , R . A . , 'Longitudinal Variations of VLF Chorus A c t i v i t y in the Magnetosphere: Evidence of E x c i t a t i o n by E l e c t r i c a l Power Transmission Lines', Geophys. Res. L e t t . , V o l . 4, No. 7, 1977, pp. 275-278.  92 Park, C , 'VLF Wave A c t i v i t y D u r i n g A Magnetic Storm: A Case Study of the Role o f Power L i n e R a d i a t i o n ' , J . Geophys. Res., V o l . 82, No. 22, 1977, pp. 3251-3260. P r i c e , A.T., 'Electromagnetic Induction in a Conductor with a Plane Boundary', Quart. Math., V o l . 3, P t . 4, 1950, pp. 385-410. Say,  M.G., Machines, 1965.  The P e r f o r m a n c e and Sir Isaac Pitman  Semi-Infinite J . Mech. A p p l .  D e s i g n of A l t e r n a t i n g C u r r e n t and Sons L t d . , London, U.K.,  T e l f o r d , W.M., G e l d a r t , L.P., S h e r i f f , R.E., K e y s , D.A., Applied Geophys i e s , Cambridge U n i v e r s i t y - Press, Cambridge, U.K., 1 976. Topping, J . , E r r o r s of O b s e r v a t i o n and and H a l l L i m i t e d , L o n d o n , 1966.  T h e i r Treatment,  Chapman  W a i t , J.R., and S p i e s , K.P., 'On t h e Image R e p r e s e n t a t i o n of t h e Q u a s i - S t a t i c F i e l d s of a Line Current Source Above the G r o u n d ' , C a n a d i a n J . P h y s i c s , V o l . 47, 1969, pp. 2731-2733. Watanabe, T., S l a w s o n , W.F., and C h a p e l , B., 'Power Harmonic R a d i a t i o n as an E.M. Prospecting Source', U.B.C. D e p t . of Geophysics and A s t r o n o m y (Aeronomy g r o u p ) I n t e r n a l R e p o r t , 1981. Weaver, J . T . , 'The G e n e r a l T h e o r y of in a Conducting Half-Space' , V o l . 22, 1971, pp. 83-100.  Electromagnetic Induction G e o p h y s . J . R. A s t r . S o c ,  Weaver, J . T . , ' I n d u c t i o n i n a L a y e r e d P l a n e E a r t h by U n i f o r m Non-Uniform Source Fields', P h y s i c s of the E a r t h P l a n e t a r y I n t e r i o r s , V o l . 7, 1973, pp. 266-281.  and and  93  APPENDIX  HARMONIC  The  use  of  transformers  is  design  the  this  and  practice  magnetic  A.1  flux  current  the  hysteresis  1965,  units  curve,  plotted  be  from  the  harmonic a  in  p.  odd  of  this  manner it  applied  content.  p.  Thus  magnetizing  situation current  The  a  In  core.  period,  T,  is  example  magnetizing here  with  is a  to  P  on  current seen  term  f i f t h .  flux  a  waveform  the  than  the  and  the  fundamental  presented  the  sinusoidal  of  sinusoidal  coupled  a  form  and  the  of  the  sinusoidal  third  a  of  e . m . f . ) ,  important  demands  However  corresponding  one  the  a  assuming  the  of  94).  plotting  material.  current.  more  voltage)  The  Q on  economical  in  of  sinusoidal the  power  r e c t i l i n e a r i t y  a  mainly  p.  of  saturation  time,  consists  94).  an  method  thro'ugh  be  of  of  for  to  cores  hysteresis  flux-density  and  the  1965,  the  from  of  to  curve  harmonics,  1965,  to  graphical  a  may  (Say,  due  effect  magnetizing  (Say,  sinusoidal  weight  function  loop  seventh  sinusoidal  a  in  requirements  departure  a  94),  and  harmonic  an  sinusoidal;  of  f i f t h  the  as  densities  problems  hysteresis  (Say,  series  of  (corresponding  shown  far  and  r e l a t i o n ,  corresponding  8  the  reduction  introduces  density  requires  by  i l l u s t r a t e s  magnetizing  ANALYSIS  induction  imposed  c i r c u i t  flux/current Figure  high  A  to  and  a  However,  the  third  (required current symmetric;  by  with a  non-sinusoidal  94  i  95 flux  (that  i s , one c o n t a i n i n g harmonics) can a l s o r e s u l t from  the same h y s t e r e s i s c u r v e . A  mathematical  (Hayashi e t a l . ,  procedure  1979)  to  determine  harmonic based on the h y s t e r e s i s material. Fourier  Essentially, series,  expressed  in  in  the  which  summation  has  loop  magnetic the  form,  the of  and  point-symmetric  v a n i s h . The l o o p f o r a (for  example,  D.C.  F i g . A.2  strength a  of  each  transformer core  Fourier  coefficients  can  be  and depends on the shape of the is  of  a  familiar  ( f i g u r e A . 2 ( a ) ) , a l l even harmonics biased  figure A.2(b)),  c o n t a i n s harmonics of a l l  developed  f l u x i s r e p r e s e n t e d as a  h y s t e r e s i s c u r v e . When the h y s t e r e s i s c u r v e shape  been  case and  the  lacks  point-symmetry  resultant  waveform  orders.  H y s t e r e s i s l o o p (a) p o i n t symmetry; symmetry (Hayashi e t a l . , 1979).  (b) no  point  96 APPENDIX  INSTRUMENTATION  The as  AND C A L I B R A T I O N  described  in  section  3.2  is  summarized  follows:  (a)  Harmonic c u r r e n t measurements at Meridian Substation;  (b)  GIC measurements  (c)  AF at  (d)  Geomagnetic  (e)  EM s u r v e y  The  harmonic  systems, and  instrumentation  B  signals the base  one  one  to  to  its  own  the  signals  are  schematically  signal  signal  in  probes generator  suggestion was  f i e l d  current  of  tape  on  a  B.1).  known  on  are  and  5L82  to  a  tape  of in  receiver  Each  c i r c u i t  the  uses and same  diagrammed  purposes, consisting  (figure  B . C . Hydro, same  devices,  is  two  (A-phase)  system  of  c a l i b r a t i o n  the  into  harmonics  apparatus  load  system.  separated  channels  test  measured  station;  amplification  (the For  base  harmonics.  resistive  R.M. Shier,  recorded  mobile  different  connected  and Mr.  probe)  the  current  current  recorder  figure were  using  single-phase  recorded  at  measurements  (current  line  b e i n g the c u r r e n t in 5L82) w i t h i n the "survey area.";  monitoring  neutral  transmission  5L82;  measurements  measure  audio-frequency  current  (source station  measure  detection  on  on  manner  B.2).  the as  the of  a  From  a  resultant the  actual  97  5L82  AUDIO FREQUENCY TAPE  (a)  FM TAPE  (b)  AF ANTENNA  O—L> N-S E-W  01  AUDIO FREQUENCY TAPE TIME CODE  (0  V/F CONVERTER FM TAPE  (d)  AUDIO FREQUENCY TAPE  (e)  Z 3 COMPONENT MAGNETOMETER  AF ANTENNA  OHt> • o-  WWV AUDIO RECEIVER PICKUP  Fig. B.1  Schematic representation of presented as figure 3 . 3 ) .  apparatus  (previously  CURRENT HARMONICS CALIBRATION CIRCUIT CURRENT PROBE  SIGNAL GENERATOR  >  -vv-<§>-  L  v  AMPLIFYING & RECORDING SYSTEM  GIC CALIBRATION CIRCUIT DC SOURCE  HALL-EFFECT TRANSDUCER  0 J  F i g . B.2  AMPLIFYING & RECORDING SYSTEM  Calibration circuits f o r harmonic c u r r e n t s and GIC d e t e c t o r ( p r e v i o u s l y p r e s e n t e d a s f i g u r e 3.4).  99  line  current  data,  thought  that  would  more  be  detecting harmonic  to  was  a  the The  effect  connection The  of  basis  placed  of  within  a  proportional current  source  is  any  c u r r e n t - l e v e l system  frequency  of  The through figure FM  GIC the  during  from  the  from  The DC  was In  resultant found  to  be  addition,  c a l i b r a t i o n ,  transmission  so  line  1  Hz,  by way  given  in  system  a  H a l l -  the  ground  Substation. which  encircles in  the  An  response  ring  is a is  adjustable  output  a  is  same  device  f i e l d  with  each  to of  remove the  low  pass  known  DC  GIC  corner  1979).  transducer  The  in  ring  transducer  to  the  Meridian  frequency  at  B.3(a)-B.3(h).  conductor.  the  the  processed  employs  this  of  tape  are  current  at  system  detection  H a l l - e f f e c t If  on  in  figures  magnetic  H a l l - e f f e c t  current.  system  a  the  to  offset.  (Boteler,  is  in  connected  current  system  5L82  c a l i b r a t e d  and  noted  Hz  of  Thus  was  testing  was  entire  signal  machine,  the  It  c a l i b r a t i o n  signal  quasi-DC  the  current  flat  of  an  Meridian.  system,  was  B.2).  tape,  the  3  is  The  input  ring.  conductor, the  measuring  detect  of  the  recording  metal  in  A-phase  transducer  to  zero  the  transformers  high-M  current-carrying  input.  detection and  Substation.  lab'  of  results  for  to  the  the used  analog  The  current  the  devices  an  charts  transducer  ' i n  amplitude  on  GIC d e t e c t i o n  Meridian c a l i b r a t i o n  an  current  analyzed.  neutral  at  site'  than  the  known  c a l i b r a t i o n  and  'on  recording  analysis  data  site  accurate  frequency,  spectral  the  this  and  c a l i b r a t e d  the  on  signal  by  passing  on was  site  that into  p o l a r i t y the the  at  to of  and  the  transformer  (see  recorded  magnitude  the  d i r e c t i o n  current  Meridian  amplified  proportional the  a  GIC  of  of  system  current  ground  is  on  was flow  shown  100 in the data  in  terms  of  conventional  current  (positive  to  n e g a t i v e charge f l o w ) . The c a l i b r a t i o n was  i n c o r p o r a t e d i n t o the  presentation  and  filter GIC  of  the  data  ( f i g u r e s 4.1  (corner frequency=2.5 Hz)  was  4.2).  A low-pass  used on the playback  the  measurements to e l i m i n a t e 60 Hz noise on the s i g n a l t r a c e . The  antenna,  AF  receiver  station  at  amplifier,  audio-frequency  DR  receiver  a  base  length  tape was  the  consisted  survey  in  For t h i s reason  The  with  s t r e n g t h was  signal  from  simultaneous  the  the  base  magnetic  readings of base s t a t i o n  station  field  ( f i g u r e s 5.3(a),  system  and  strengths 5.4(a),  induction  the  AF  and  component). The  and  magnetometer  one  high-^  performed.  signals  base  particular  station  frequencies  at  the  base  air-core coils  metal  core  station  (N-S  vertical  and  coil  a m p l i f i e d n a t u r a l s i g n a l s are recorded  r e c o r d e r . The  with  C.4(b)).  used  orthogonal  data.  the mobile r e c e i v e r system  at  C.4(a),  of two mutually  orientation)  tape  s e n s i t i v i t y of the a i r - c o r e c o i l  the  component has been c a l c u l a t e d t h e o r e t i c a l l y and  e x p e r i m e n t a l l y . I t i s convenient  to express  in terms of Caner, that i s as an e l e c t r o - m o t i v e f o r c e induced  1 mr  nn  in  amplitude  (note  that  a  in  sensor  frequency of  (Z  for  checked  the s e n s i t i v i t y  a s i n u s o i d a l magnetic f i e l d v a r i a t i o n of 1 Hz  E-W  on a slow  speed FM N-S  of  in  r e q u i r e d from base s t a t i o n  y i e l d e d a s c a l e which i s used i n the data showing  consists  an  base  monitoring  no a b s o l u t e c a l i b r a t i o n procedure was  However simultaneous  The  an  work. Thus only i n f o r m a t i o n r e g a r d i n g r e l a t i v e changes  magnetic f i e l d  both  of  of l o w - r e s i s t a n c e c a b l e , and  recorder. used  station  t r a n s m i s s i o n l i n e harmonic c u r r e n t s , and as a r e f e r e n c e EM  of  1 Caner  (V ) a  by and in  101  s e n s i t i v i t y , with  a  (10~ 1  1  placed  frequency Tesla),  2  microvolt  (Hayashi  of  voltage f i e l d  uniform  Hz  and  rise et  resistance  impedance  1  a  to  a l . ,  external  with an  an  magnetic  amplitude  f i e l d 1 my  of  electromotive  force  of  1978a)):  Caner  a  D . C .  of  gives  V = 0 . 1 27 The  within  the  for  of  the  amplifier  the  c o i l  is  7.50  amplifier,  variation  of  1 Hz  is  5.45  and  1  by ,  my  the  Therefore,  kn.  created  and  kfl  a  the  sinusoidal  w i l l  input input  magnetic  be  obtained  the  ratio  by  PP multiplying input  the  impedance  e.m.f. to  the  induced  sum  in  of  the  the  c o i l  by  input  impedance  of  and  the c o i l  resistance:  Input  voltage:  0.127  „ V X P  The  total  gain  G=2X10  of  the  0.127  „V_ P  output X  a c t u a l i t y , and  0.2  frequency.  whole  in  1.47  mVp  output  frequency.  G,  voltage  the  for  p  for  a  tape  for  less  magnetometer  The  the  system  frequencies  amplifier,  of  7.50 7.50 + 5.45  P  amplifier Hz  7.50  P  +  is  5.45  2X10 : 5  5  Therefore,  In  the  7.50  for  low-pass  N-S 1 my  at  frequencies  components  in  Therefore,  0.1 less  is  P  connected  frequency  induced  component  p p  reject  the  Hz.  is  be:  mV  5  to  e.m.f. 0.1  2X10 =14.7  f i l t e r  recorder  the  w i l l  P  However,  than the  X  e.m.f.  between higher  response  the the  calibrated  c o i l  is  output to  the than  of  the  flat  for  of  the  be:  Hz than  0.1  Hz  is  proportional  to  1 02 The  AF  antenna, of  mobile  amplifier,  the system  field  was  created  solenoid  by  is  magnetic  induced  a  at  of  function  recorder  used  amplifier  with  the a m p l i f i e r  survey.  gain  The  increase  the  B.4,  two  and  gain  and  the  gain  of  circuit  settings,  a  signal  of and  as  is  resultant  emf  on  t h e DR  tape  ( i n t h e same m a n n e r  field  position recorder  system  are given  In  and used  by  calculations  calibration  AF  was  the a m p l i f i e r  the  strength.  receiver  system  results,  in figure  a  source  i t s design. The  gain  of  The  The  treated  this  recorded  source  into  the tape  generator.  t o be  of  magnetic  i n the c a l i b r a t i o n of  settings.  position gain  in  mobile  control  the graphical gain  results  i n the lower  overall test  separate  gain  antenna  the antenna.  frequency  to record  calibration  field  and  air-core  The  the signal  data),  settings  higher  calibration figure  has  of  portable  antenna  magnetic of  a  recorder.  to a  the  i s amplified  of  a manual  the  different  The  the survey  incorporates  from  analysis  as a  the  connected  position  i n the antenna  analysis  three  enough  the  Spectral  tape  solenoid  of  tape  by p l a c i n g  source.  recorder.  consists  and p o r t a b l e  done  far  dipole  calculated  system  system  The  addition, calibrated three  i n the  field  i s designed  are  dB. given  showing B.5.  the  signals  the  22  as  to The in the  A P H A S E C U R R E N T C A L I B R A T I O N (60 Hz) -10 -20  dB  -30  -to -50 -60 -70  500  100  Amps  F i g . B.3(a) C a l i b r a t i o n c h a r t :  A-phase - 60  Hz.  1000  (rms)  o  A P H A S E C U R R E N T C A L I B R A T I O N (120 H z) — —•  1  . . :. • T  I  • :::::::: ...I.  .". i •*  :  dB  i  —  . . . . i..  : : : j • •; : : : I  . .(. :i  I  1  .  :: I." i '•I i ... i. i  T'~7."  -  ~  :  i  i" T1.  1  1  •T.  : :  ;  ; •;  ..i...  !. 1  as  -  —  - — -: • :  • i  io  i.  | 1• •-:!:. :::!:::  :  I  I •  ...1..  •  ^_  1. ..  SJO  A-phase - 120 Hz.  :• ir  1  • !: . . 1 ...  Amps (rms)  B.3(b) C a l i b r a t i o n c h a r t :  1.. 1 .  ;;;;  ! - .1r.  . 1-  .  —T—  :  • i  -  \::| •  ; ; -  :  i . i. "i-  •|  " . .1  .VM. \ 1 TTH—  .—  j  • i  1  —  •  r : >.. j : :  I-  \OJQ  ••: 1.  —  1  sao  A P H A S E C U R R E N T C A L I B R A T I O N (180 Hz) •U -10 -20  dB  -30 -40 -50 -60 -70  as  5.0  LO  Amps  F i g . B.3(c) C a l i b r a t i o n c h a r t :  A-phase - 180  Hz.  10-0  sao  (rms)  o  A P H A S E C U R R E N T C A L I B R A T I O N (240 Hz) i  r  i :  1i 1 i  -ijii:  .: _  :  J  : .-- '  .:.-|  -  -  -  — l .  dB  -~l -  ..  'z.-i-r.i _••_ : • :  .1  ,  : I" •i  J •- '  • I- : -  i. •  T[: -  1  i- :  • • • f • • •  __:  'j  ."..I : .1  .  1 - 1 - 1 1.:  i _ ' : ir—  -  ... i . .vi:-  -  :  : rl  : L:.:  :K  . -  :  • .::-;.;-:.-f•-. z  :  : :  Lift  i:"i"  -.1. ::! •  1  r- :  —— r-: r.:— ;  7—:  TT-:  '  as  :  '  _•  '' '  _i  -  ~-r-r.  '  - .-.  -—?  '  :-:  .::  i 1  -r-~  1  ...  ;  1  " -  . h ::)-: 1. L.ZL  -.-.:..  ... :  :  rr:":  ii:  :  :-r-~--  : ~T' ~: r -  ;  *f  :::•{:•:  —1— I j  .  _ 'Z . . ....  ::::|r..  :•:  I  -  I  -  LO  ...  J. •  -  ni: 1 I I I —  1  1  I  1  I  SXJ  : :r: :  I  I  I I  •  ... |:r t' 1 \ 1  -  lao  Amps (rms)  Fig.  B.3(d) C a l i b r a t i o n  chart:  A-phase  - 240 Hz.  o CTl  A P H A S E C U R R E N T C A L I B R A T I O N (300 H z ) :  ,:.r.::  ;  !ii . _-rr :  :.  : : : r  ••:  dB  '  rrr:  1 ::::)::::  : i -i.;i i1' •  |  rrrr  ...  .. j.. (... rrrr  ;  r:: :-i::  T" ;.: r. :**;  :r:  :  - ::••  — -— .-  ; r; i  -r3rrr _rfr:  ;-i:• -I.  :T:  rrj;::: :::•]::.  i  ;  -rrrrr:  :  :•:  _..p_  m  . . -;:  as  :  '  ; :  :  -  _.  ::::j:::: . -•);;::i; .. ; :i:iiii: -iiiiir  -::::: ....  ;r  i-i  loo  ;-  iiiiiii'. ....I.  •  ':•}'  .. u.  :  ;  ;  :  ;  [:;•: :.:|.::.  ::r  rf:' rrr:r:  rrrr:.: rr r:  Irrr I•"  — l.  5.0  io  . ii.  •: - ;  :;:.|:, T-T— —r-  :;;:!:.........  :  r. i: .:-:  :. 1 . :•:.!:.  rrrr :~;  \Z'.'.  .:  '""'; r :: :  ....  _-  : .1...ri-"'  r r r r : rr:  —-•  : r  • ^ :  :••;•:  ::rr:r  r.r:r;  .r.:::.:  : ::.:•  :  Lrrrri ~r?  :rr£ 7  • 7  •••• '•; :-:-T'i-L  rHlr:: ::::r::::  :.  ••• i . : . : .  ;;;.-i:r. r:r  ........  — - --  :..-|-  iri  :  ::  :  iiii  =.-;  I  • . • ^ ! : ; ; . . r .:  ::'|: ::::;::.. :  •  -: .7  :::•!::.  i I TIrufr|iii'-Liir  ::::;:::. ;;:..  :.-  "rr:  ;-• r-i  ii;'-!:.:.  !  '-_  :  1  -rirr rri:::  irLfK •:•;•;?  -;:: - -:;  h  :::i:r:  •'• rrrrf.  :  :;; - r - ; :  rtrr rr  • T-  sao  Amps (rms)  Fig.  B.3(e) C a l i b r a t i o n c h a r t :  A-phase - 300 Hz. o  A P H A S E C U R R E N T C A L I B R A T I O N (360 Hz) : ,. :  -iii  :  i ~:  :  -  -ii iiLL ii"  zrz-: rz.-  "iz  •zzz^Br. r.  zz:  -  zr  zr.: -zz-  ;...f---  -:  :  zrrr  zzz:  T=_  rrr: r L  ::  T~ -  '-.  ::•!;;;  :.  :zz  rzz rrr  --: " H  Hi! -r  •  •:::!'•*  :  rr • :  1  rfff  '-  'zz'--J \\rz-  : -  :'zz  ::-  ...  _..  :;  -'- -\  :ji: ;  -  ::..!• . .: :::...j .  z  :  fiii ii  :: :  iiiVzzl  -  ::  ;  :  .|.:  •!:'  : Hi..!.: .I.~"z:  .. ;  •-: -ir:.  '-: ~-r: •••rr:  ZZ  :l  . z :..-.-  ™ T~T' ~T:. :  . i i i".  i. : : :  -.\  z'z---z-  -. _  : ~ . ; : : .:  100  :  :.  r_-  :  •:i  '-'"}"••  :r; ::r|.:.. :.:.!. . 1 ::i:  '1 '  H— zzl—  1:1: r:  :  UTT: ii:i  '.'  "' !!•  r  1  r.-r-ff i#*:i= :  -iii- -  .[:'. : :].:•i | .  T::i r::r rrr  'il:: LT*.  :  i -\-z  ii iii-i i:  :r iii'" rrTi  SO  :::r-  rrrl  :  .::  I -r Hi: :|:r .... ... r: tr  ..  ZZ  • ::-r.-;  ;;  ••'4:;  10  :  r:  ii;  i 'z\  l  _ :r  \±  - 1:  rr-:: z::z ::  -r~r-  "\  :  "-  :' ! '  ;:;:  .. :1 ._: -  :  t ir ir  ii  : ^ :: VT  i.  -^z\:  •  ::.-  l-izizi  ~z:r:  L  : |::::l.  :>  :  :zz.  —  :  Tfzrr' ii=r i:V  rri:-'  :::: •rr  . i... rrr  z' l •  •  :  rr  T" ~ '  :._-::  - ..v.:.: : . z :  [rz  -  :- r .-"  .4  •• j:  :\-  .::  •'-.\:~r  ;  z=\  ii;  -"iirf  dB  ,:  .zr:  iiii  :  •zr.l  :  |::r :.! ; : :.: i  5O0  Amps (rms)  F i g . B . 3 ( f ) Calibration chart:  A-phase - 360 Hz.  o oo  A-PHASE CURRENT CALIBRATION (420 H z - 660 Hz) -10 -20  dB  -30 -40 -50 -60 -70  500  Amps (rms)  F i g . B.3(g) C a l i b r a t i o n c h a r t :  A-phase - 420 Hz-660 Hz.  o  to  N E U T R A L C U R R E N T C A L I B R A T I O N (60 H z 6 6 0 Hz) i . i  i' • •  1 ! • :• 1" • ! • '  : .J: : - !: i -  . |  \." 1:.:.  i. i  i  :  • 1 :  1  -j  I . I  '  !  •  • i . J..  . j .  "!' '  i  ...  :;:;| : .  • _l_  0.5  ....... --- •; 1.0  •  j  1•• :  5D  Amps  F i g . B.3(h) C a l i b r a t i o n c h a r t :  1 .  "T" •1  !  (rms)  N e u t r a l - 60 Hz-660 Hz.  • T  1  1  .  ' I  1. . .  J  -r-j--  i• i  " "j  •:::[:•• : .  L:.  ... j , •  .... ....  • • :! •l : : . .. ;  ]•  -••---1-! • •  • j  •"!'."'"  I I  •. •  - --—\- -  •  1  Fl"'  .. ! I  r•  :i  - . :.  -H-V-:  i  - — — j -  dB  -  :•• | '  i  • :  ]  ;  !  :  10.0  1 .  .  .. i': . :  • ;  i ; SOJO  -i  111  lP(x.y)  Coil  Magnetic dipole  area Ac = ( 2a f a=0.25 m d=3.50 m turn number Nc=40 Total flux through c o i l :  •=N - //B(x,y)dxdy C  c  A  Magnetic Field at P(x,y):  4irr  M=dipole moment r=J(x+d)2 +y2  3  Magnetic Flux Density at P(x,y): Therefore:  * -£  B= UH  n A M/dx/  y2]3  in 4ir ^(x+d)2 +y2  , dy 2  Upon evaluation of integral: -2P.NCM f(d2i2a2_i2da)1'2 (d2 • 2 a - 2da>' | , 2  * "  4 l r a  I  d«a  2  J  d-a  - U.NcMa j3  2  nc  Since the assumption d>>a holds, we can assume the f i e l d of the solenoid at o i s equivalent to that of a dipole, therefore: M=IA  S  I=current in solenoid A " t o t a l area enclosed by current I s  To f ind area A : s  Let n=winding per unit length of radius (assumed constant) Total turn number N,"25,000 v v N « / n ( r ) d r • n / d r • n(v-u) s  u  u  A, =/irr n(r)dr « un/ r d r 2  2  u  u  A, - l n ( v - u ) = 3  2u=38.2 mm 2v=95.3 mm  intv-uX^+uv+u )  3  2  A, =2NS (v +uv+u ) 2  2  Cross-Section of Solenoid Thus the magnitude of the flux through the c o i l  (ignoring sign):  • ' W.N N I (v +uv+u )^32  C  Then i f we define B  n g  2  S  as the average magnetic flux density at o: ZTZ."  Iivi±uv+uil 1?rt  (Tesla)  3  It i s in this manner that the mobile receiver system i s calibrated, as the E M F induced by B (which i s calculated) i s amplified and recorded on tape the same way the data i s recorded in the f i e l d survey.  F i g . B.4  Schematic diagram o f calibration circuit c a l c u l a t i o n s f o r m o b i l e AF r e c e i v e r system.  and  1 12  FREQUENCY  F i g . B.5  (Hz)  Sensitivity (mV/nT) c a l i b r a t i o n chart for mobile AF receiver system (least squares f i t to data; dashed lines indicate ±5% bounds attributable to s c a t t e r ) .  113 APPENDIX C  EM-SURVEY DATA ANALYSIS  The was  first  to assign  magnitude of  the  stage values  of  the  to  total  each  mobile  magnetic  f o u r f r e q u e n c i e s (60 Hz,  determined graph.  As  from  the  was  also  signal.  By  dividing  station lost,  signal, and  that,  used  1.0  Library  cases  in  1/4,  the  the  data this 1/50,  exhibit The  Hz,  the  300  base  of t h e  mobile  station  station  contoured SCATCN  time  of  data  the  such  the  i s then  be  data,  U.B.C.  that  contour data  equally-spaced contour  by  station  a  the  the  base  easier  to  a  (noting  station  to  the  1.0).  Computing  values.  is  stations  normalized  contours  values  of  field  between 0 and  which  fitting  was  receiver  i s • the c l o s e s t  used,  Hz),  calibration  magnetic  t o make a n a l y s i s  the  each  t h e base  signal  p o i n t s using p r e - d e f i n e d contour work,  420  The  at  dependancy  receiver  survey  station.  station,  Hz,  text,  values w i l l  was  t h e EM  u s i n g the proper  eliminate  a t the base s t a t i o n  program  scattered  to  by  5.2  m e a s u r e m e n t s . The  source, a l l mobile at  data  at each  t h e measurements a t a l l t h e m o b i l e  since  arrive  180  from  receiver  field  the a b s o l u t e v a l u e  become r e l a t i v e of  raw  discussed in section  receiver  value  i n a n a l y z i n g the data  To  Centre  a  s e t of In  are  1,  1/2,  1/r  falloff  a l l 1/3, will  lines.  p r o g r a m SCATCN c o n t o u r s  the  scattered  data p o i n t s i n a  1 14  two-stage  process.  a r t i f i c i a l  values,  a r t i f i c i a l which  values  can  regular  grid  locations  the  which  then  surrounding  each  octants.  a r t i f i c i a l  weighted  average  (the  weighting  factor  data of  point  to  a r t i f i c i a l  the  values  a r r i v i n g  at  work,  program  a  the  total  of  The taken  the  2200  the  is  1/d , 2  then  area  an  inaccurate  representation  Thus  contours  points, routine,  as  is  figures  insufficient the  data The  to  are  "reference the  is  in  of  the  very  used  of  the  data  areas  grid  CNTR.  X  In  in  this  50,  for  the  data  results  in  a r t i f i c i a l of  few  outputs  e r r a t i c  contours,  the  grid.  or  actual  an  no  data  of  the  due  to  presentation  of  5.4.  presented effect  The  frequencies.  points  in  octant the  contour  four  in  ignored  to  from  presented  to  e r r a t i c  were  into  points.  the  These  region  each  44  the  equal  to  measuring  was  the  in  a  contains  divided set  input  grid  contain  evaluated).  by  in  is  in  three-  the  is  of  CNTR,  a  distance  maps  grid  third  point  data  section  theoretical  grid  no  C . l ( d ) .  field"  the data  each or  -  a  of  and  the  being  as  here  few  points,  5.5)  where  indicated  C.1(a)  data  (figure  indicate  of  c l e a r l y  data  generated  for  Obviously  the  closest  contoured  described  grid,  of  contained  the  grid-point  d  The  dimensions  intersection)  used  a r t i f i c i a l l y  area  a  the  produced  are  and  grid  program  consists  two  intersection  SCATCN  survey  of  which  points,  (or  the  actual  process  in  of  grid  f i r s t  a  values.  Library  SCATCN  generates  value  is  the  to  data  generates data  points  the  grid-point  the  actual to  input  scattered  SCATCN  The  the  data  The  in  program  sent  contour  array,  values.  on  then  pattern.  of  the  based  is  only  dimensional  their  F i r s t ,  of  in  section  the  5.4  geometry  was of  included  the  power  115 l i n e , assuming a 1/r B i o t - S a v a r t  r e l a t i o n . T h i s was  by  of  mapping  the  configuration  transmission  s e r i e s of connected l i n e segments. The area"  was  properly  represented  region  developed which c a l c u l a t e d the t h e o r e t i c a l  at  a  e f f e c t s of the equation  point  for a l i n e  The  w i t h i n the "survey  finite  "survey  line  l i n e 5L82 i n a  of  the  "survey  i n r e l a t i o n to 5L82. A program  was  specific  accomplished  segments,  magnetic  field,  a r e a " , by summing the  using  the  Biot-Savart  segment:  area"  can  be represented  by a f i n e l y  spaced  g r i d , the value of the magnetic f i e l d B then c a l c u l a t e d at grid  point,  contoured in  and  the r e s u l t a n t g r i d of magnetic f i e l d B values  d i r e c t l y by CNTR. The  f i g u r e 5.6,  stations included  area,  the  field"  primary  s i n c e i t assumes  field  f i g u r e 5.6  for  mobile purposes  receiver of  within  the  f i g u r e C.2  was  compiled.  The  stations  were  comparison with  a c t u a l d a t a ) . To show the i n n a c c u r a c i e s inherent program,  given  independant of the l o c a t i o n of the mobile r e c e i v e r  (the l o c a t i o n s of the in  r e s u l t of t h i s method was  l a b e l l e d the " r e f e r e n c e  the t h e o r e t i c a l c a l c u l a t i o n of survey  each  same  in  the  program  the  SCATCN which  1 16 generated  the  theoretical  field  data  reference  theoretical  value  and  Thus  represent  to  profiles  graphical data,  relation log  compiled normalized  linear  log-log  gives rise ±10% are  C.2  66  mobile  only d i f f e r  form effects error  simply  plotting  and  of  f o r an  are  line given  t o the d a t a ,  to  coverage. 5.4)  was  that they  are  data.  The  original  data  measurements)  overall  in  view of  inverse plot of  size  fairly  t o show d e v i a t i o n s from  ( n o t e t h a t an  to a s t r a i g h t  the  low  the the  base s t a t i o n are  by  (section  random  tend  a  receiver  SCATCN f a i l s  i n r e g i o n s of  field  plots  random e r r o r  fitted  the  profile  to the  plots  much more c l e a r l y  the p l o t s  on  a  a  1/r log-  slope -1). Error  f o r each data  the  bars  point,  c o n s t r a i n i n g to a slope  of  and -1  possible. One  point  perpendicular locations  However, still of  presented  of to  are  constrained  shift  by  generate  the  of  secondary  to  a t the base s t a t i o n ) of  figure  in  used  the  set. Obviously  associated  the  indicating  data  the d a t a  f o r m . The  scale  where  the  and  while  and  was  i n p u t t o t h e p r o g r a m was  1.0  at each  presented  were  (referenced  5.6  show t h e  than  The  h i g h l y s c a t t e r e d data  data  intended greater  of  such  The  field  figure  coverage  field.  plots  (normalized to  f r e e - s p a c e magnetic stations.  contour  a  by  it  interest the  result  easy  h o l d s , and the  source,  vehicular  is  entire  in this  is  of  that  and  are  available  accessibility  t o show t h a t t h e in fact plot,  thesis:  the  only  the p r o f i l e s not data  do  not l i e  parallel.  p o i n t s , w h i c h were  within  the  region.  inverse r e l a t i o n change  w h i c h d o e s not  Their  is  affect  of  the  a  vertical  the  analysis  let  y(d)=^ log  The  w  d  y=-log d  geomagnetic  (l)=i_=  _L_  d  IsinG  =  constant 1  l o g w=-log 1 + l o g (constant)  field  was  monitored d u r i n g the EM  so that times of i n c r e a s e d a c t i v i t y c o u l d be recorded. As in chapter s i x , the geomagnetic f i e l d activity  during  into consideration completeness,  the  was  recorded  on  tape  was  a d d i t i o n to concurrent mobile results figure  are  the  in  not taken  results.  For  magnetometer r e c o r d i s i n c l u d e d here i n f u l l  ( f i g u r e C.3). Also., a s p e c t r a l sample signal  of  stated  moderate  EM survey measurements, and was  i n the i n t e r p r e t a t i o n  the  q u i e t to  survey,  plotted  C.4(a)-C.4(b).  as  a  taken receiver  of  the  every  base five  station  station  AF  minutes, i n  readings.  The  f u n c t i o n of time, and are g i v e n i n  118  F i g . C . I ( a ) Contoured d a t a - 60 Hz.  119  Fig.  C.1(b) Contoured d a t a  - 180 H z .  120  F i g . C.1(c) Contoured d a t a - 300 Hz.  F i g . C.1(d) Contoured data - 420 Hz.  122  F i g . C.2  T h e o r e t i c a l d a t a i n SCATCN program  123  124  BflSE-60  Hz  0 -20  dB-40 -60 -80 22 J U L Y 1981  LOCAL  23  TIME  J U L Y 1981  BASE-180 H z  (rms)  M7  22 J U L Y 1981  Fi9  ' * JS'S. anf TSS°S» ^ C  LOCAL  23 JULY 1981  TIME  4(a)  ^ 2 / 7 / 8 1 - 3 2  /  7  /  8  i  ):  BflSE-3.00 Hz  nT(rms) MO  H  1G  2 2 JULY 1981  18  I  "T" 10  20  LOCAL  ~1  12  TIME  16 23  JULY 1981  F i g . C.4(b) Base station AF 300 Hz and 420 Hz.  LOCAL  signal  TIME  20  JULY 1981  BflSE-420 Hz  22  18  (rms)  23 JULY 1981  (22/7/81-23/7/81):  

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