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The dissipation factor method of ascertaining the moisture content of newsprint Chu, Gan Dick 1949

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L  £*&7 THE DISSIPATION FACTOR METHOD OF ASCERTAINING THE MOISTURE CONTENT OF NEWSPRINT  Gan Dick: Chu A Thesis Submitted i n P a r t i a l Fulfilment of The Requirements for the Degree of MASTER OF APPLIED SCIENCE In the Department of MECHANICA1 AND EIECTRICA! ENGINEERING  Approved:  In Charge of Major Work .  fie&d dt Department.  THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1949  THE DISSIPATION FACTOR METHOD OF ASCERTAINING THE MOISTURE CONTENT OF NEWSPRINT by Gan Dick Chu  Ever since newsprint was made on a mass production b a s i s , there has been a r e a l need f o r a simple and instantaneous measurement of the moisture content of the moving sheet.  A  knowledge of the moisture content i s important both economic a l l y and t e c h n i c a l l y to the m i l l operator.  As newsprint i s  sold by weight, the moisture content of the paper must be maintained within a narrow s p e c i f i e d range.  The m i l l , natur-  a l l y , s t r i v e s to produce paper with as high a percentage of moisture as permissible. Without any s c i e n t i f i c means to guide them, however, the machine operators tend to overdry the paper because an overdried sheet i s not nearly so noticeable as one that i s too moist.  This means that less paper i s being  made than i s p r a c t i c a l l y possible f o r each cord of wood processed.  In addition, the overdried paper i s of i n f e r i o r  q u a l i t y t o that containing the proper amount of moisture. present, the only r e l i a b l e method of measuring moisture  At con-  tent i n Canadian m i l l s i s the laborious oven method which, though undoubtedly very accurate, has the great disadvantage of time l a g .  The recent development of the Q-meter offers a  method f o r the r a p i d measurement of the moisture content of the moving sheet by the d i s s i p a t i o n f a c t o r method which has the advantage that no contact with the paper i s r e q u i r e d , The f a c t that the d i e l e c t r i c constant  of water i s  very h i g h compared t o that of c e l l u l o s e suggests that the d i e l e c t r i c losses i n moist paper could be used to measure i t s moisture content*  Tests were therefore conducted i n the l a b -  oratory w i t h a Boonton Q-Meter, type 160-A, t o determine the d i s s i p a t i o n f a c t o r of newsprint samples of various moisture contents. A p a i r of p l a t e s w i t h the sample of newsprint between them, but not touching, c o n s t i t u t e s the t e s t condenser. The d i s s i p a t i o n f a c t o r of t h i s condenser depends l a r g e l y upon the amount of moisture contained i n the newsprint.  To mea-  sure the d i s s i p a t i o n f a c t o r , the t e s t condenser i s tuned to resonance with a high-Q i n d u c t o r .  The amplitude of resonance  depends on i t s <£ value which i n turn i s l a r g e l y a f u n c t i o n of the condenser l o s s e s .  Henoe the d i s s i p a t i o n f a c t o r may  c a l i b r a t e d against the percentage moisture  be  content.  R e s u l t s of laboratory t e s t s at d i f f e r e n t h u m i d i t i e s and various frequencies showed that the percentage moisture content can be measured w i t h adequate accuracy.  The speed  t e s t s showed that the speed of the paper up to a v e l o c i t y of 1800 f e e t per minute between the condenser p l a t e s has e f f e c t on the readings.  no  A l l these p r e l i m i n a r y t e s t s i n the  l a b o r a t o r y i n d i c a t e that i t i s f e a s i b l e to apply the Q-meter f o r measuring the moisture content of the moving sheet by -fflie  d i s s i p a t i o n f a c t o r method.  Exhaustive f i e l d t e s t s under  a c t u a l m i l l production c o n d i t i o n s should be made over a p e r i o d of time t o compile s u f f i c i e n t data f o r a f a i r a p p r a i s a l of the p r a c t i c a l value of t h i s method.  .  £  TABLE OP CONTENTS  PAGE  I  Introduction  4  II  Review of l i t e r a t u r e  6  III  Survey of E x i s t i n g Methods of Measurements . . . . .  10  17  Investigation  ••  15  ••••  15  A. Theory of measurement 1.  Composition and d i e l e c t r i c constant of paper  15  £•  Ideal condenser c i r c u i t  3.  Ideal r e s i s t o r c i r c u i t  17  4.  Imperfect condenser c i r c u i t  17  5.  Equivalent c i r c u i t for imperfect condenser • • • •  B.  ....  •  18  Description of test c i r c u i t and apparatus . .  SO  1.  Test c i r c u i t and analysis •  £0  £.  Q-meter theory •  £6  3.  Test condenser assembly and humidity  •  chamber 4.  £9  Test assembly for effect of speed of paper  C.  16  31  Experimental results 1. Procedure  £.  34 •  (a)  Stationary tests  (b)  Speed tests  Observations  34 34  •  35 ' 36  (a)  Data, of stationary tests  36  (b)  Data of speed tests  36  3  7  D i s c u s s i o n and Prospectus  4S  71  Literature cited  45  711  Acknowledgment...  48  T i l l l i s t of Symbols  49  IX  Graphs  •  51  X  Appendix  •  57  4  THE DISSIPATION FACTOR METHOD OF ASCERTAINING THE MOISTURE CONTENT OF NEWSPRINT I  INTRODUCTION  From the economic p o i n t of view, i t i s d e s i r a b l e i n 'a. paper m i l l to be able t o measure the amount of moisture i n the sheet of newsprint while i t i s moving through the paper machine.  Because newsprint i s s o l d by weight and t h i s weight  depends l a r g e l y upon the water contained i n the paper, the purchaser s p e c i f i e s that the water content s h a l l be kept below & c e r t a i n maximum.  On the other hand, the paper m i l l  s t r i v e s t o produce paper w i t h as h i g h a moisture content as p e r m i s s i b l e because the higher the moisture content, t h e l e s s i s the amount of c e l l u l o s e b u l k per ton.  Hence a m i l l must  maintain the percentage moisture content of i t s newsprint w i t h i n a narrow range.  A t y p i c a l working range i s from 7  to 1 0 per cent. The advantage of measuring the moisture content i n the moving newsprint before i t i s wound up i s that there i s s t i l l time f o r making adjustments t o the dryer c o n t r o l s i f necessary.  Otherwise i f measurements were made a f t e r the  paper i s wound i n t o r e e l s and should the water content be found t o be too h i g h , the whole r o l l would have t o be d r i e d out.  On the other hand, i f the paper be found t o be too dry,  very l i t t l e can be done t o the r o l l t o remedy t h i s .  The mea-  surement o f the moisture content i n a sheet of paper moving  5 a t a speed o f 1500 f e e t per minute or more through a modern paper machine,is, however, not a simple procedure. Because the d i e l e c t r i c constant of water i s very h i g h compared t o that of c e l l u l o s e , the main objeet of t h i s t h e s i s i s t o show that the d i s s i p a t i o n f a c t o r of paper oan be used f o r the r a p i d measurement of the moisture content i n the high speed moving sheet. As the p r i n c i p l e o f t h i s method depends mainly upon the d i e l e c t r i c losses i n the paper, a b r i e f review of the fundamental concept o f d i e l e c t r i c l o s s e s Of ft condenser i s o u t l i n e d , then the b a s i c t e s t c i r c u i t i s described and a mathematical a n a l y s i s i s given. Ho determine the moat s u i t a b l e frequency, t e s t s were made w i t h a Boonton S-Meter, type 160-A, a t d i f f e r e n t f r e quencies ranging from 150 Kc. t o 5 Mo. From measurements made on samples of newsprint standing s t i l l between a p a i r of condenser p l a t e s i n a humidity chamber, experimental data were c o l l e c t e d , tabulated, and p l o t t e d on graphs.  F i n a l l y to i n -  v e s t i g a t e what e f f e c t the speed of paper had on.the Q-Meter readings, measurements were made on a sample d i s c of newsprint s p i n n i n g up t o a speed of 1800 f e e t per minute between a s e t of s e m i - c i r c u l a r p l a t e s .  6  II  REVIEW OF LITERATURE  The p r i n c i p l e s of suseeptanee-variation, frequencyv a r i a t i o n , or voltage-comparison i n resonant c i r c u i t s have been used i n the determination of the power f a c t o r and the d i e l e c t r i c constant o f i n s u l a t i n g m a t e r i a l s .  Hartshorn and  Ward (12)* made use of c a p a c i t a n c e - v a r i a t i o n i n a tuned c i r c u i t w i t h a vacuum-tube voltmeter as a resonance d e t e c t o r to measure the p e r m i t t i v i t y and power f a c t o r of i n s u l a t i n g m a t e r i a l s over a range from 10 k i l o c y c l e s t o 100 megacycles. Adjustments are made by means of two micrometer condensers. Both the p e r m i t t i v i t y and power f a c t o r are obtained as the r a t i o of capacitance readings. Yager (23) used an e x t e r n a l condenser connected i n p a r a l l e l w i t h t h e - i n t e r n a l tuning*-,' condenser o f a Boonton 0-Meter, type 100-A, t o measure the frequency v a r i a t i o n o f the d i e l e c t r i c constant and d i e l e c t r i c l o s s f a c t o r o f v a r i o u s p l a s t i c s over a frequency range from 100 k i l o c y c l e s to 3 . 5 megacycles.  Wood (22) r e c e n t l y i n  England measured the moisture content of a sheet of c l o t h moving between a p a i r o f condenser p l & t e s .  The Q of t h i s  condenser i s measured and compared w i t h the Q. of a c a l i b r a t e d c i r c u i t , and any d i f f e r e n c e s are used f o r c o n t r o l purposes. Except f o r higher speeds, the problemi of moisture measurement i n paper m i l l s i s about the same as t h a t i n the ?  Cited.  *A11 numbered references are given i n l i t e r a t u r e  7 t e x t i l e m i l l s , and hence i t should be f e a s i b l e t o apply the Q-meter f o r measuring moisture i n paper m i l l s . Extensive researches have been c a r r i e d out on the measurements of d i e l e c t r i c constant, power f a c t o r , and d i e l e c t r i c l o s s e s of i n s u l a t i n g m a t e r i a l s .  I t i s well-known  that adsorption of moisture by any i n s u l a t i n g m a t e r i a l causes a large increase i n i t s d i r e c t - c u r r e n t c o n d u c t i v i t y and i n the power l o s s d i s s i p a t e d under a l t e r n a t i n g v o l t a g e , liibben (11) i n v e s t i g a t e d i n great d e t a i l , the v a r i a t i o n o f c a p a c i t y , t&nd (where 6 i s the l o s s angle of the d i e l e c t r i c ) , and the d.c. c o n d u c t i v i t y w i t h percentage moisture content f o r telephonecable paper.  As shown i n Figure 1, the increase of tancf,  and hence the power l o s s , becomes more r a p i d as the moisture content i s above 4$. Minton (15) i n v e s t i g a t i n g the v a r i a t i o n  Paper (3 Samples) Iiubben. tan6  0  0  5  0  /  J  0.020  O.0/O •1 Log 0005 rur1 o 0002 0/2 %  3^0-6 Moisture  789 Confcaf  Fig. 1 of percentage power f a c t o r w i t h percentage moisture content f o r pressboard found a s i m i l a r r e s u l t . A d i e l e c t r i c by ordinary electromagnetic theory i s  8 c h a r a c t e r i z e d g e n e r a l l y by i t s two constants:  (i) itsd i -  e l e c t r i c constant and  A c t u a l l y , how-  ( i i ) i t s conductivity.  ever, the behavior of d i e l e c t r i c s i s found (11) t o be  not  s o l e l y determined by these two constants because a l l s o l i d and l i q u i d d i e l e c t r i c s show c e r t a i n p r o p e r t i e s which seem to be quite independent of them.  These p r o p e r t i e s are u s u a l l y  c a l l e d t h e i r anomalous or abnormal p r o p e r t i e s and the most important of these anomalies i s the power l o s s occurring i n an a l t e r n a t i n g f i e l d .  Many t h e o r i e s have been suggested to  e x p l a i n these anomalous p r o p e r t i e s of d i e l e c t r i o s .  Among the  more well-known ones are Maxwell's Theory of the l a y e r D i e l e c t r i c (16), ( E l ) , and Debye's Dipole Theory (11). Maxwell s t a r t e d with the assumption that a l l d i e l e c t r i c s have both the ordinary d i e l e c t r i c constant and c o n d u c t i v i t y , and that under an e l e c t r i c force they f u n c t i o n simultaneously independently of each other.  and  For s i m p l i c i t y he assumed t h a t  a d i e l e c t r i c i s b u i l t up of a number of plane s t r a t a of d i f f e r e n t m a t e r i a l s , and stated that a medium formed of a conglomeration of s m a l l pieces of d i f f e r e n t materials would behave i n the same way.  This l a t t e r statement, however, was  not supported by f u r t h e r a n a l y s i s .  By t h i s theory, i t i s  assumed that wvery d i e l e c t r i c which shows absorption c o n s i s t s of a mixture of two or more d i f f e r e n t m a t e r i a l s even though i t may appear to be homogeneous under the c l o s e s t examination. The d i f f e r e n t values of the d i e l e c t r i c constant and  conducti-  v i t y i n the successive l a y e r s of Maxwell's l a y e r eondenser fire used t o account f o r the r e l a t i v e l y long time necessary f o r  9  complete charge and discharge of a condenser.  Debye assumed  that the molecules of some materials are not symmetrical and that they therefore possess permanent e l e c t r i c moments. When such m a t e r i a l s are placed i n an e l e c t r i c f i e l d , the molecules are  r o t a t e d so as to b r i n g t h e i r axes i n alignment with the  field.  I f the molecules are free t o r o t a t e , they assume a  d e f i n i t e o r i e n t a t i o n t o c o n s t i t u t e a p o l a r i z a t i o n of the material.  The d i e l e c t r i c constant of the m a t e r i a l i s increased  by such o r i e n t a t i o n s of the p o l a r molecules.  I t i s probable  that the r o t a t i o n of the molecules of l i q u i d s and s o l i d s are opposed by f r i c t i o n a l forces depending on the v i s c o s i t y of the  material.  The e f f e c t of these forces w i l l be t o r e t a r d  the  p o l a r i z a t i o n due t o the p o l a r molecules and thereby gives  r i s e t o the phenomenon of d i e l e c t r i c a b s o r p t i o n and power l o s s i n alternating fields.  10  III  SURVEY OF EXISTING METHODS OF MEASUREMENTS  Ever s i n c e paper waa f i r s t made on a mass production b a s i s , a r e a l need f o r a simple and instantaneous measurement of moisture content of the moving sheet has confronted m i l l operators.  To date, the only r e l i a b l e method commonly used  i n Canadian paper m i l l s t o measure moisture content i s by the weighing of a paper sample before and a f t e r d r y i n g i n an oven. The standard technique  of t h i s p e r i o d i c sampling i s s p e c i f i e d  i n TAPPI Standard T-412-m^42.  There i s no doubt of the h i g h  degree of accuracy of t h i s oven method, but i t has the b i g disadvantage of time l a g t o the extent of s e v e r a l hours. During t h i s time l a g , many r e e l s of paper are wound up before any adjustments can be made, i f necessary.  Moreover, c o n d i t i o n s  may have changed w i t h i n t h i s time l a g . Hence to overcome t h i s disadvantage, the moisture content of the moving sheet must be measured d i r e c t l y and r a p i d l y to give instantaneous readings. Some methods have been devised u t i l i z i n g such measurable c h a r a c t e r i s t i c s of the sheet as r e s i s t i v i t y , humidity, temperature, t e n s i o n , and work done by the sheet f o r an i n d i c a t i o n of the moisture contained.  One method (3) uses a  s e n s i t i v e s t r i p of cellophane i n a box s t r e t c h e d across the paper machine so that the web of the paper runs over an open face of t h i s box.  The vapour from the sheet w i l l e i t h e r  lengthen or shorten the s e n s i t i v e cellophane s t r i p , to operate a r e l a y that c o n t r o l s the dryer temperature a c c o r d i n g l y .  11 I n another method commonly used (3),  a light roller  suspended  from hinged arms r i d e s on the sheet i n the space between two dryers.  When the sheet i s damp, i t w i l l sag under the weight  of the r o l l e r s to move the arms.  This movementtwhich i s pro-  p o r t i o n a l t o the dampness of the sheet, i s used to c o n t r o l the dryer steam pressure.  I t was found that t h i s method kept  the moisture i n the sheet a t a u n i f o r m i t y that i s b e t t e r than the p r e c i s i o n of most moisture t e s t s a t the dry end of the machine• Of the e l e c t r i c a l systems devised t o date f o r moisture measurement on paper machines, none seems to have won general acceptance i n i n d u s t r y .  The Yerigraph made by the  Foxborq Company of Poxboro, Massachuettes, U.S.A. e s s e n t i a l l y measures the humidity of the moving sheet w i t h a h a i r hygrometer enclosed i n a shoe that i s r e s t i n g on the sheet. A l though i t has been i n s t a l l e d i n a few m i l l s i n Canada, the Verigraph i s not i n use because of d i f f i c u l t i e s i n g e t t i n g the e l e c t r i c a l c i r c u i t s to f u n c t i o n p r o p e r l y . Brown Moist-O-Sraph (5) of Chicago, U.S.A.  Another i s the  made by the Brown Instrument Company  This instrument uses a Wheats tone bridge  to measure the r e s i s t a n c e of the moving sheet between two rollers.  I t s operation i s based on the r e l a t i o n s h i p between  the moisture content and t h e e l e c t r i c a l c o n d u c t i v i t y of the paper sheet.  According to a June, 1948  report (18),  this  instrument has been tested i n the l a s t t e n years under a c t u a l production c o n d i t i o n s . of the Moist-O-Graph  These f i e l d t e s t s proved the a b i l i t y  t o operate s u c c e s s f u l l y i n m i l l s pro-  IE  dueing a variety o^ papers including newsprint.  Tests showed  that variations i n machine speed, mechanical draw, machine v e n t i l a t i o n , furnish, c a l i p e r , and sheet formation do not affect the c a l i b r a t i o n .  However, i t was found that changes  i n the type of dye used or i n the pH of the stook do affect the c a l i b r a t i o n .  This shift i n c a l i b r a t i o n i s said to be so  small that the instrument readings remain accurate and r e l i able within the l i m i t s of sampling as long as the changes i n dye and pH do not exceed those which can be tolerated i n the manufacture of a given type of paper.  In other words, to pro-  duce a noticeable effect i n the instrument c a l i b r a t i o n , i t i s claimed a change i n the dye or the pH must be of such amplitude that the quality of the finished products w i l l be s e r i ously affected and w i l l be r e a d i l y noticeable to the machine tender.  The biggest factor, though not mentioned i n the above  report, should be variations of c a l i b r a t i o n due to temperature changes which are inherent i n a l l r e s i s t i v i t y measurements. Because of these c a l i b r a t i o n shifts due to one or more v a r i ables, some m i l l operators have an aversion to the r e s i s t i v i t y method. According to the January, 1949 Monthly Report of th» Applied Science D i v i s i o n , Powell River Company (10), experiments are being conducted on an e l e c t r o s t a t i c dryness indicator using the varying length of glow i n a s p e c i a l l y made gas discharge lamp to indicate the amount of moisture i n the sheet.  Although the experiments were q u a l i t a t i v e l y s a t i s -  factory, the proper glow-discharge lamp has not yet been made.  13 Perhaps due to lack of a more r e l i a b l e and quick s c i e n t i f i c method, i t i s common i n the m i l l s today for an operator to test the moisture content i n a moving sheet by feeling the top of the paper with an open hand.  This method  i s , of course, subjeet to human limitations that vary with the judgments of different i n d i v i d u a l s .  Moreover, with no  indicating device to guide them, the operators tend to overdry the sheet since an overdried sheet i s not nearly so noticeable as one that i s running on the moist side.  This i s the  c r i t e r i o n machine operators used to produce an acceptable sheet, but the consistent production of overdried paper i s a detriment to both m i l l economy and paper q u a l i t y . Newsprint containing less moisture must contain more cellulose per ton so that for each eord of wood processed less paper i s being made than i s p r a c t i c a l l y possible.  In addition, the overdried  paper i s of i n f e r i o r quality to that containing the proper amount of moisture. To be accepted generally by the m i l l s , any new moisture content measuring device must overcome a l l limitactions inherent i n the principles and methods used such as low degree of accuracy, slowness i n response, o r i t i c a l n e s s to variables, and dependence on i n d i v i d u a l judgment.  It i s  believed that the d i s s i p a t i o n factor method investigated i n this thesis can give a rapid and accurate indication of the moisture content by measurement of d i e l e c t r i c losses with a Q-meter which i s a laboratory instrument developed only a few years ago.  This method has also the advantage that no contaet  14  with, the paper i s necessary. Furthermore, no s p e c i a l l y trained or h i g h l y - s k i l l e d technician i s required to operate the Q-meter i n this dissipation factor method.  15  IV A.  INVESTIGATION  THEORY OF MEASUREMENT  Composition and D i e l e c t r i c Constant of Paper Fundamentally,  paper may be defined as an  aqueous deposit o f c e l l u l o s e .  The pulp stock i s a  suspension of minute c e l l u l o s e f i b e r s i n water which a c t s as a c a r r i e r t o deposit these f i b e r s onto a wire screen. The water i n the c e l l u l o s e deposit i s s u c c e s s i v e l y removed i n the f o l l o w i n g steps:  d r a i n i n g , a p p l y i n g s u c t i o n from  the under side of the screen, p r e s s i n g the newly formed sheet between r o l l s , and f i n a l l y passing the sheet through a. s e r i e s of dryer r o l l s that are heated a l l y by, l i v e stdam.  intern-  Hence the general f u n c t i o n of a  paper machine i s t o reduce the water content o f t h i s pulp mass and smooth i t out evenly t o form a sheet. F o r newsprint, the amount of water removed i s from 95% a t the wet end down t o around 6 or 7% a t the dry end of the machine. The d i e l e c t r i c constant i n paper i s found t o be a v a r i a b l e depending upon the moisture content.  At  a low moisture content, the value of d i e l e c t r i c constant (3) i s only around 25 i n s t e a d o f i t s normal value of 80 f o r l i q u i d water.  The e x p l a n a t i o n given by Hartshorn  and Wilson (13) i s that the h i g h d i e l e c t r i c constant of water i n the l i q u i d s t a t e i s almost e n t i r e l y  due t o  16 the orientation of i t s polar molecules i n an e l e c t r i c field.  The rotation of molecules forming the top layer  of an adsorbing surface i s severely limited because they are strongly held to the surface.  In the successive  layers underneath, the molecules are less and less securel y held so that the ease for greater changes of orientation increases with each layer u n t i l such a depth at which the molecules have the same freedom as those i n the l i q u i d form. Ideal Condenser C i r c u i t .  F i g . £: Consider the case of an i d e a l condenser cons i s t i n g of two plates separated by a i r and connected to an alternating sine-wave generator, as shown i n Figure £. The condenser, C^, w i l l alternately charge and discharge for each cycle.  During the charging h a l f of the cycle,  when the voltage across C^ i s increasing, energy w i l l be received from the generator.  During the other h a l f of  the cycle, when the voltage across C^ i s decreasing, the condenser w i l l discharge and return energy to the generator.  I f a l l the energy required to charge the condenser  i s completely returned to the generator on discharge so that none i s consumed i n the process, the condenser has a zero power factor.  17 3. Ideal Resistor C i r c u i t .  T Fig. 3 Figure 3 shows the case of the perfect r e s i s t o r , l o e l e c t r i c a l energy can be stored so that the energy absorbed by R must be completely dissipated. i  This  perfect r e s i s t o r has a unity power factor, and the current i s i n time phase with the voltage. 4.  Imperfect-Condenser C i r c u i t .  W///M  Fig. 4 Uow consider the ease when the space between the ideal-condenser plates i s f i l l e d with d i e l e c t r i c other than a i r as shown i n Figure 4 .  The condenser w i l l  charge and discharge as before but the d i e l e c t r i c w i l l dissipate some of the energy absorbed.  This d i s s i p a t i o n  of energy i s caused, i n general, by two independent processes: (i)  losses due to conduction of e l e c t r i c a l charges.  (ii)  losses associated with the vibrations or movements of atoms and molecules.  18  Equivalent C i r c u i t for Imperfect-Condenser. Regardless of what process by which energy i s dissipated, the results oan he obtained by a study of the equivalent c i r c u i t .  For analysis, the imperfect condenser  may be replaced by an equivalent i d e a l or lossless condenser shunted by a resistance of conductance, Rp, as shown i n Figure 5.  In this equivalent c i r c u i t , C , the  Fig. 5 capacitance of the i d e a l condenser i s equal to 6 times that of the d i e l e c t r i c - f i l l e d one of Figure 4, where £ i s the d i e l e c t r i c constant of the i n s u l a t i n g material.  The  resistance i s of such a value that the same amount of energy w i l l be. dissipated i n this c i r c u i t as that of Figure 4. The current vector diagram of t h i s equivalent p a r a l l e l c i r c u i t i s shown i n Figure 6 . c  J  where:  0  «  Fig.  phase angle,  s  6  6=  - loss angle.  9O°-0  *p = current i n the condenser branch su>CE Ieosd =  I I  R  B  s  current i n the resistance branch jE_ - I s i n d =  t o t a l current = 1 - I . Q  R  I  19 The d i e l e c t r i c loss = W E I sincf =  r E sin  6  mCE eostf  = EwC tano It i s convenient to have the general r e l a t i o n ship between the components of the equivalent p a r a l l e l and series c i r c u i t s shown i n F i g . 7, where H and 0 s  S  are  the series components, R and Cp are the p a r a l l e l components. p  (I /VW^^WV^  enes Parol lei  Fig. 7 Equate the current drawn by each c i r c u i t : I =E Rp  E ^  =  E  B - JZ s  Rationalizing:  E__ - _ E _ % P  S  . ER R* + xg  :  EXg  S  J X  JCHJ t  Z§)  Equating the r e a l and imaginary teims: R  p  =  R (1 a  r2  +  Z|)  -  H (1 + Q ) = R s ( l + 1 2  8  )  If  Z-  Z ( l + R§) - Z ( l + 1 ) : X g d r D ) 2  =  g  Q  ^  if  where Qi = Z , and D Rs g  Dividing:  R^ = R Q Z,s a  •'•  Q  = l  =Z  =  1 - d i s s i p a t i o n factor R .1^ Z D'  =  s  s  s  =  R  p  Hence the Qi for a p a r a l l e l c i r c u i t i s the r a t i o of i t s resistance to i t s reactance.  2.0  B.  •  DESCRIPTION  QP  TEST  C I R C U I T  A H D  APPARATUS  Test C i r c u i t and Analysis* B a s i c a l l y the test c i r c u i t i s shown schematic a l l y i n Figure 8. ,  L  R,  c  TT  F,IG.  :«,  ®  8,  where: 1 R  = inductance of the e x t e r n a l i n d u c t o r . z r e s i s t a n c e o f the e x t e r n a l i n d u c t o r .  L  9A  =  o&.paei"tiQS of the main and venier tuning condensers of the Q-meter.  C B S capacity of the t e s t condenser, e x t e r n a l l y connected. R  B  s r e s i s t a n c e of the t e s t condenser e x t e r n a l l y connected.  E ^ z fcnown value of input voltage from the o s c i l l a t o r . V r vtvm reading o f the voltage across the condensers. c  21 To find the Q of the test condenser (Q^) F i r s t consider the c i r c u i t when the test condenser assembly  i s not connected.  the basic c i r c u i t of Figure /  TPPPT  /  8  This simplifies  to that of Figure "9„  ww-  Fig. 9 where C = capacity at resonance. 0  JLt resonance  o>2L = JL,  (1)  '0  (2) E  L  UJC  Q  R  L  Next consider the' c i r c u i t with the test condenser assembly connected as shown i n Figure 10, —nswp— WA /  ©  c  F i g . IP where G  r s  capacity to resonaite c i r c u i t with the test condenser connected,  let  Z-£ - impedance of the test condenser -  ~ &t*t  (3)  22  let  Zp r equivalent p a r a l l e l impedance of G Z  Z Zt + Zt  „ where Z ; - J X ,  r  r  r  T  r  and Z^.  _ Xj. -  i UJC,  -Wt  (-jX ) r  -3*t t R  Ht * J' t x  =  XyXt + (4)  Rationalizing 2p  where  R  e  (5)  =  =  (4)  + ^Xy)  ii-Rfy  X^ R  -  e  = x|xf  +  2  R|(X  t  + Xj.)  2  (6)  dx,  e  + R|(X • X )2 t  r  y ^ t ^ t » r)" xfxf + R | ( X . + XJ,) £  *e =  2  Then the c i r c u i t s i m p l i f i e s to Figure 11*  •^RW  (7)  ^  F i g . 11  (8)  23 JLt resonance then  Q  wl* - Z w  a 3  B  ~  =  L  Bi+ a  e  He  1  1 Z. _ + Q R (Z 0  Hence  _  Q  t  R  t  0  m  t  t  r  t  -  V W ^ t  -  Solving f o r Z  r  t  z  where  + Z )  t  Q R (Z * Zr) R tZ + Z ; + ^ZtZj. t  Solving f o r R  e  + Zj,  t  QQ 0  8  t  3 <5 Z e  =  *Er«r 2  "  m^Z^ (Z  t  yr + Z y J d + nT)  24 then  Z z  VT^ + > - Z ( l + m ) + m (Z ) 1  t  M  2  2  e  r  (17)  -z  e  z U  +  2  r  +  i f m i s very large, then  i £12^* -  .'. Z+ "^e ^ * ~ ~*e *r  2- 1  (18)  1  (19)  2  +  Putting Z -uiL = e  wc  r  then  1 , X^,. " Z  - ^ o ^ r t ~ ^1 + 1 UJG"£..  uuC  r  1 1  (20)  ml  1  t = m-  uuO -u)C + uuG, r  M*. Q  0  -  Q  r  ,  1  s  UJC  0  (21)  25 then hy E v e r i t t ( 6 ) p. 81 for a p a r a l l e l c i r c u i t Q  t  =  X  z  =  t <*oQ« . 1 .  1 Wi0  = Ma  ( c  o "  c  ) r  o  - c j r  ,  (S2)  26 Q-Meter Theory. B a s i c a l l y , a Q-Meter i s composed of three main units:  (a) an o s c i l l a t o r ,  (b) a measuring c i r c u i t , and  (c) a c o u p l i n g f o r the o s c i l l a t o r to the measuring circuit.  This fundamental c i r c u i t i s shown s c h e m a t i c a l l y  i n Figure 12.,  .  OSCILLATOR  Fig.  12  A c a l i b r a t e d voltage, B  i t  i s s u p p l i e d from the  o s c i l l a t o r to the s e r i e s c i r c u i t by passing a measured current through the low r e s i s t a n c e , E. A s h i e l d e d t r a n s mission l i n e terminating i n a thermocouple and at 0.04 ohm non-inductive r e s i s t o r are used as the means of c o u p l i n g . The measuring c i r c u i t c o n s i s t s of  main and  vernier  tuning condensers together with a vacuum-tube voltmeter which measures the voltage developed across the condensers.  When a c o i l i s connected t o the e x t e r n a l c o i l -  t e r m i n a l s , A and B, the s e r i e s c i r c u i t i s tuned t o r e sonance as i n d i c a t e d by a maximum d e f l e c t i o n of the Qvoltmeter t o give the Q of the c i r c u i t .  27 The c i r c u i t can be f u r t h e r s i m p l i f i e d as shown i n Figure 13 f o r mathematical a n a l y s i s . L  R  L  F i g . 13 where  1  - inductance of the e x t e r n a l inductor.  Rj  r e s i s t a n c e of the e x t e r n a l i n d u c t o r .  =  C  A  - capacitance  R  Q  z r e s i s t a n c e of the tuning condensers.  of the tuning condensers.  A t resonance, the reactances are *L  • o x  The voltage across C i s given by v  c  =  ¥ c  z Hi + R  S i ; Jo 21 X a  L t l Qi Q  ft 0  0  c  equal.  28  In most c i r c u i t s , the r e s i s t a n c e of the condenser: i s ? n e g l i g i b l e compared to that of the i n d u c t o r so that Q  0  > »  Qj,. ThJis the voltage across the con-  denser i s equal to the product of the i n j e c t e d voltage times the e f f e c t i v e Q of the resonant c i r c u i t , hence V  Q  s  Since the i n j e c t e d voltage, Bj_, i s of a fcnown  value, the voltage across the condenser, Y , may be c a l i 0  brated i n terms of  and the ammeter, M, may be c a l i -  brated as a m u l t i p l i e r of the ^-voltmeter readings. A f r o n t view of the Boonton Q-Meter type 160-A i s shown i n photograph #3 and the schematic c i r c u i t diagram i s shown i n photograph #4 i n the Appendix.  29 Teat Condenser Assembly and Humidity Chamber. The  t e s t condenser c o n s i s t e d o f two c i r c u l a r  D u r a l p l a t e s , 3 inches i n diameter and  inch thick.  E a c h p l a t e i s f a s t e n e d t o the end o f a 5 i n c h diameter  8 p o l y s t y r e n e r o d w i t h a countersunk f l a t h e a d screw a t the c e n t r e o f the p l a t e .  Through s n u g g l y - f i t t e d h o l e s i n  b a k e l i t e panels mounted on each s i d e of the chamber, each p o l y s t y r e n e r o d can be a d j u s t e d so t h a t the d i s t a n c e between the p l a t e s may be v a r i e d . The l e a d - i n connections t o the p l a t e s a r e made a t the bottom w i t h banana-plugs inserted i n a The  i n c h p o l y s t y r e n e p a n e l f o r low l o s s e s *  e n t i r e humidity  chamber i s c o n s t r u c t e d o f wood and  i s p a i n t e d w i t h s e v e r a l c o a t s of enamel p a i n t . F o r o b s e r v a t i o n the door i s made o f •% i n c h t h i c k l u c i t e . chemical balance  A  i s mounted over the top o f the chamber  and a t h i n thread attached t o the bottom o f one pan i s dropped through a s m a l l h o l e a t the top o f the chamber. The paper sample i s suspended f r e e l y between the two condenser p l a t e s by t h i s t h r e a d . humidity,  To o b t a i n a c e r t a i n  two pans of a s a t u r a t e d c h e m i c a l s o l u t i o n a r e  p l a c e d i n s i d e the chamber.  This whole  arrangement i s shown i n F i g u r e 14.  experimental  Luc/te  \y Door  Test  Conc/eoser  Plate  • Sa/ar<zfec(  31 4.  Teat Assembly For  f o r E f f e o t o f Speed of Paper. t h i s t e s t , the c i r c u l a r D u r a l Condenser  p l a t e s were r e p l a c e d by two U-shaped p i e c e s o f 3 i n c h  8 t h i c k b r a s s as shown i n F i g u r e 15..  These p l a t e s were  designed i n 3_« t h i s shape so that the p e r i p h e r a l speed o f 32  Fig. the the  15  paper p a s s i n g between the outer and i n n e r r a d i i o f p l a t e s would be about the same.  The t e s t newsprint  samples are cut i n t o 6-inch diameter d i s c s w i t h a s m a l l hole i n the c e n t r e f o r clamping onto a 3 i n c h diameter  8  d r i l l r o d which runs between b a l l b e a r i n g s mounted a t eash s i d e o f the chamber. An e l e c t r i c motor mounted a t the  top o f the chamber d r i v e s the d r i l l r o d through a  b e l t and p u l l e y s .  By v a r y i n g the v o l t a g e i n p u t to the  motor w i t h a 1-ampere General Radio v a r i a c , any d e s i r e d speed of the paper from s t a n d s t i l l t o f i v e sand f e e t per minute may be o b t a i n e d . is  or s i x thou-  This t e s t  shown conneoted to the Q-meter i n photographs  and #£.  assembly #1  02  •0 * 0  Photograph  fl showing, the Humidity Ghaiaber Assembly -  for Speed Tests, the Type 160-A Q-Meter, and the Type 103-A Inductors.  23  Photograph #2 showing a  close-up  view  of the Humidity Chamber connected to the 4-Meter.  34 C. 1.  EXPERIMENTAL BE SUITS  Procedure. (a)  Stationary Tests  For the stationary newsprint tests, a 6" hy 9* 1  sample of 32 l b . newsprint* was suspended by the thread between the Dural plates which were set 1_ inch apart. 32 The two pans of a saturated solution were placed i n the chamber overnight.  Next day, the lead-in connections  from the test condenser plates were connected to the Q-meter and the suitable Type 103-A Inductor for that particular frequency band was plugged into the Q-meter. After the Q-meter was warmed up, the Q-multiplier meter was adjusted to read 1 and the Q-meter was tuned to resonance with the capacity d i a l . Q and the capacity.  Readings were taken of the  By varying the frequency from 150  k i l o c y c l e s to 5 megacycles and changing the Inductor for the different frequency bands, readings of Q and the capacity were taken at each frequency.  F i n a l l y , the paper  was weighed with the chemical balance.  For the second  part of the t e s t s , the paper sample was removed and the. whole set of Q and capacity readings was repeated at each frequency. *The 32 l b , newsprint specification means that 500 sheets, size 24" by 36", weigh 32 l b s .  35 In t h i s i n v e s t i g a t i o n , readings were taken a t three d i f f e r e n t c o n d i t i o n s of moisture content and the f o l l o w i n g saturated s o l u t i o n s were used t o o b t a i n these different humidities: (i) (ii) (iii)  6.45$ moisture content - no s o l u t i o n used. 11.6$ moisture content - Ca(N0g) ,4Hg0 s o l u t i o n . &0.6$ moisture content - NagSO^*lOHgD s o l u t i o n . 2  (b)  Speed Tests  The paper d i s c s were clamped onto the d r i l l rod w i t h b a k e l i t e f l a n g e s and the s e t screws t i g h t e n e d . The s e m i - c i r c u l a r brass condenser p l a t e s were brought together t o about 1 inch a p a r t . 16  By checking the speed  of the d i s c w i t h a Strobotac, the r e q u i r e d speed was obtained by adjustment of the v a r i a c .  Readings: were  taken of Q: and C when the d i s c was r o t a t i n g a t 1100 f e e t per minute, 1850 f e e t per minute, and a t s t a n d s t i l l .  The  d i s c had t o be removed from the chamber and weighed i n the balance.  This i s not a very accurate method but as  the primary object i s ; to determine the e f f e c t of speed, an approximate percentage moisture content i s s u f f i c i e n t .  36 Observations fa)  Data of S t a t i o n a r y Tests  The r e s u l t s of the t e s t a a t the various moisture content are tabulated i n the f o l l o w i n g t a b l e s : (i) (ii)  Table I Table I I  - a t 6.45% moisture content. - a t 11.6% moisture content.  (iii)  Table I I I - a t 20.6% moisture content. Then the values of the Q of the paper sample,  (O^) are c a l c u l a t e d from the f o l l o w i n g formula:  ^ = MilVlJl' where: s Q. of the c i r c u i t without paper d i e l e c t r i c . s Capacity of t e s t condenser i n uuf without paper dielectric. - Q of the c i r c u i t w i t h paper d i e l e c t r i c . Cg  Capacity of t e s t condenser i n uuf w i t h paper dielectric.  C  Q  s Capacity i n uuf to resonate the inductor alone. These values of  are tabulated i n Table IV  and p l o t t e d g r a p h i c a l l y i n Figures 16 to*21.  (b)  Data of Speed Tests  A l l the r e s u l t s of these t e s t s are tabulated i n Table V.  37  TAB IS I Q-Meter Headings of Test on Newsprint Sample of 6.45$ Moisture Content  INDUCTOR TYPE 103-1  FREQ. Without Newsprint Ql  No. 32  150 200 250 300 350 400 500 600 700 800 900 1000 1100 1200 1.5 2.0 2.5 3.5 4.0 4.5 5.0  No. 31 No. 22 No. E l No. 12 No. 5  Kc. Kc. Kc. Kc. Kc. Kc. Kc. Kc. Kc. Kc. Kc. Kc. Kc. Kc. Mc. Mc. Mc. Mc. Mc. Mc. Mc.  Dl  165 360 177 167 176 76 194 196 191 124 185 73 171 320 189 200 200 125 207 76 187 232 195 174 199 129 201 94 170 366 190 171 201 79 194 331 200 234 20E 164 206 116  With Newsprint  Cl  Q2  90 86.5 87 86 82 86 85 83 82 83 80.5 80 80 81.5 84 82.5 83 80 84 87 86  155 158 146 171 161 149 158 165 165 159 164 163 160 155 156 157 145 166 161 153 144  »2 348 156 64.5 184 112.5 62 309 . 188.5 114 65 218 160 116 81.5 355 160 67 317 220 151 103  c  2  102 97.5 98.5 98 93.5 97 96 94.5 93 94 94.5 94 93 94 95 93.5 95 94 98 100 99  Where: Ql s Q: of the c i r c u i t without paper d i e l e c t r i c . Dl Capacitor-dial reading i n uuf without paper d i e l e c t r i c . Cl Capacity of test condenser i n uuf without paper d i e l e c t r i c . s (C - D i ) . 0 C s Capacity i n uuf to resonate the inductor alone. Qg s Q of the c i r c u i t with paper d i e l e c t r i c . DJ2 = Capacitor-dial reading i n uuf with paper d i e l e c t r i c . Cg s Capacity of test condenser i n uuf with paper d i e l e c t r i c . * ( C - Dg). s  s  0  tf  0  38  UBIE  II  Q-Meter Headings of Test on Newsprint Sample of 11.6$ Moisture Content  INDUCTOR TYPE 103-A  No. 32  FREQ.  150 200 250 300 350 400 500 600 700 800  No. 31 No. 22 No. 21  900  1000 1100 1200 1.5 2.0 2.5 3.5 4.0 4.5 5.0  No. 12 No. 5  Kc. Kc. Kc. Kc Kc. Kc. Kc. Kc. Kc. Kc. Kc. Kc. Kc. Kc. Mc. Mc. Mc. . Mc. Mc. Mc. Mc,  Without Newsprint  With Newsprint  Ql  *>1  Cl  Q  165 177 176 195 191 185 171 189 200 207 185 195 199 201 170 190 201 193 199 202 206  359 164 73 • 196 124 73 320 200 128 76 233 174 132 95 366 170 79.5 330 235 164 122  91 89.5 90 86 82 86 85 83 79 83 79.5 80 77 80.5 84 83.5 82.5 81 83 87 80  145 141 126 161 148 136 152 159 156 150 162 163 160 155 154 156 143 164 159 152 140  2  »2  0  346 152 61.5 183.5 112 61 309 190 118 66.5 223 164 122.5 86 356 160 69 319 225 155 112  104 101.5 101.5 98.5 94 98 96 93 89 92.5 89.6 90 86.5 89.5 94 93.5 93 92 93 96 90  2  Where: Ql = Q of the c i r c u i t without paper d i e l e c t r i c . Di - Capacitor-dial reading i n uuf without paper d i e l e c t r i c . C]_ - Capacity of test condenser i n uuf without paper d i e l e c t r i c . =  ( C  0  -  DL).  C - Capacity i n uuf to resonate the inductor alone. Qg = Q of the c i r c u i t with paper d i e l e c t r i c . D Capacitor-dial reading i n uuf with paper d i e l e c t r i c . ^2 = Capacity of test condenser i n uuf with paper d i e l e c t r i c . = (C - Dg). 0  2  =  0  39  TAB IE I I I Q-Meter Readings: of Test on Newsprint Sample of 20.6$ Moisture Content  INDUCTOR TYPE 103-A  Ho. 32  FREQ.  150 KG. 200 Kc. 250 Kc. 300 Kc. 350 Kc. 400 Kc. 500 Kc. 600 K c 700 Ko. 800 Kc. 900 Kc. 1000 Kc. 1100 Kc. 1200 Kc. 1.5 Mc. 2.0 Mc. 2.5 Mc. 3.5 Mc. 4.0 Mc. 4.5 Mc. 5*0 Mc.  No. 31 No. 22 No. 21 No. 12 No. 5  Where  With Newsprint  Without Newsprint  165 177 176 194 191 185 171 189 200 207 185 195 199 201 171 190 201 194 200 201 206  J>1.  Ol  Q  365 170 78 195 121 71 319 200 124 76 229 170 129 93.5 365 170 77.6 330 234 164 115  85 83.5 85 87 85 88 86 83 83 83 83.5 84 80 82 85 83.5 84.4 81 84 87 87  89 72 56 85 72 60 103 94 83 75 103 98 90 81 117.5 99 80 132 122 109 98  2  ^2  c  347 154 63 . 184 110 61 308 189.5 114 67 218 160 119.5 84 356 160 68 320 224 154 105  103 99.5 100 98 96 98 97 93.5 93 92 94.5 94 89.5 91.5 94 93.5 94 91 94 97 97  2  Q. of the c i r c u i t without paper d i e l e c t r i c . reading i n uuf without paper d i e l e c t r i c . l - Capacitor-dial Capaoity of test condenser i n uuf without paper d i e l e c t r i c , (C - D ) . Capacity i n uuf to resonate the inductor alone. Co I Q of the c i r c u i t with paper d i e l e c t r i c . 2 - Capacitor-dial reading i n uuf with paper d i e l e c t r i c . Capacity of test condenser i n uuf with paper d i e l e c t r i c . (C - D h  D  0  X  0  2  D  4 0  T&BIE I V  Calculated values of  INDUCTOR TYPE 103-£  the Q of the newsprint sample.  FREQ.  % A  No. 22 No. 31 No. 22 No. 21  No. 12 No. 5  150 Kc. 200 K c . 250 K c . 300 Kc. 350 Kc. 400 Kc. 500 Kc. 600 Kc. 700 Kc. 800 Kc. 900 Kc. 1000 K C 1100 Kc. 1200 Kc. 1.5 Mc. 2.0 Mc. 2..5 Mc. 3.5 Mc. 4.0 Mc. 4.5 Mc. 5.0 Mc.  68.1 64.0 61.3 61.4 57.1 53.0 56.5 52.7 50.1 47.5 59.8 54.8 50.8 48.4 46.3 39.5 38.5 39.2 36.4 32.7 30.8  B 34.5 22.2 31.2 40.9 28.2 25.5 37.0 25.4 24»4 22.6 41.6 29.0 27.2 34.8 26.4 34.4 22.1 27.8 24.8 22.0 21.6  Where: A newsprint sample of 6.45$ moisture content. B - newsprint sample of 11.6$ moisture content. C = newsprint sample of 20.67« moisture content. B  C 7.73 7.66 7.55 6.50 6.16 5.60 7.04 6.94 6.85 6.65 8.16 7.75 7.46 7.35 8.34 8.14 7.86 10.00 9.85 9.50 9.25  41  TABIE V SPEED OF PAPER TESTS con  FREQ.  No. 42  50 Bo.  SPEED  4  N Ni Q  No  100 Ko. NO. 32  150 Kc. 300 Kc.  No. 22  500 Kc. 1000 K c .  N Hi 0  No. 21  1500 Kc. 2000 Kc.  No. 12  3 Mc.  Ni Ng N NI U  No.  2  5 Mc.  96  5i S;  4  70.9  418  152  419  tt  tt  tt  tt  185 it  tt  82 tt  tt  184  tt  82.2  it  tt  tt  tt  it  170  376  166  379  tt  it  it  it  73.5 193  it  it  tt  tt  tt  tt  tt  84.2 190  86  tt  ti  36.8  tt  tt  tt  it  tt  it  tt  tt  it  86  n tt  tt  37.2  it  it  it it  185  380  184  375  tt  tt  tt  ti  tt  it  it  tt  70  tt  tt  it  tt  142 tt  152 n  164 tt  172  418 tt tt  81.8 tt tt  378 it  tt  74  tt  tt  ti  tt  174  85.2  it  tt  it  tt  149 tt  186 it  n  36.5 184  it  75  ti  tt  194  tt  tt  74.5  tt  199  tt  it  tt tt tt  86  it  tt  tl  it  it  6  Hi  tt  35.5 166  TEST No.6 D 84 130  %  tt  it  K  5  96  it  154  u  No N  tt  tt  200  l  tt  tt  ii  tt  l  69.2 tt •  tt  tt  tt  0  tt  TEST No.5 D5 ^5 75 378  tt it  N 195 it Ni No • it 170 ^0 it % tt % 204 0 tt N  4 Mc.  2  NO  W  It  tt  Ni  N  Tt  tt  ?8  N  TEST No.4 04 D 376 79 tt  169 it  tt  184 tt ti  36.6 tt tt  87 tt  tt  37.5 tt it  376 it  ti  Where: N S» when paper i s .stationary. N^ when paper i s moving at 1100 feet per minute. N - when paper i s moving at 1850 feet per minute. 0  =  p  =  Test ,;io. 4 No. 5 No. 6  Weight i n gms. 0.992 1.006 1.050  Moisture Content 7.0% 8.5% 13.3%  Q-Meter Readings  Capaoity-dial Readings i n uuf. D 4  Dfi  4  D  6  42  7  DISCUSSION AND PROSPECTUS  The results of this limited investigation have shown that: (1)  The moisture content of newsprint can be r a p i d l y measured by the Q-meter with adequate accuracy*  (2)  The speed of the paper even up to a velocity of 1800 feet per minute between the condenser plates does not have any effect on the readings of the Q-meter.  (3)  The results i n the lower radio-frequency range are better than those i n the megacycle region. The slopes of the curves i n Figures 16 to 21.  show that there i s sufficient variation i n the Q of the paper sample for a small change i n percentage moisture content i n the 7 to 10% moisture content range. The results i n the megacycle region may be i r r a t i c because at such high frequencies, increases i n the resistances due to skin effect and Stray .impedances i n the Q-meter affect the accuracy of the readings. As the object of this investigation i s to establish the f e a s i b i l i t y of applying the dissipation factor method for the determination of moisture content i n newsprint, these tests are of a preliminary nature and a l l were conducted i n the laboratory on one type of newsprint only.  The value of the  results would undoubtedly be greatly enhanced, i f f i e l d tests had been made under actual production conditions i n a m i l l  43  where the readings could be calibrated against those of the oven method. Exhaustive f i e l d tests over a period of months or years are necessary to compile sufficient data for a f a i r appraisal of the p r a c t i c a l value of t h i s method. IPurther investigations are required to determine what effect other variables have on the readings such as variations i n :  (l) f i l l e r ,  ( 5 ) ambient temperaturei  (£) stock,  ( 3 ) dye, ( 4 ) pH,  ( 6 ) thickness of,paper.  Tests should also be conducted on other types of paper as well as newsprint. A l l these tests could best be conducted i n cooperation with interested paper m i l l s . A few other refinements are suggested as follows: (1)  The size of the test condenser may be made small enough so that the moisture i n only a small area may be checked. Since the moisture content across the sheet width i s not uniform, a pair of plates may be moved across the sheet to measure the moisture content at certain spots, or else a number of test condensers may be i n s t a l l e d at intervals across the sheet so that the spot of maximum moisture content may be detected i n s t a n t l y .  (2)  Automatic control of the dryers may be achieved by using the output qf the- Q-meter to actuate the controls through relays.  (3)  Once the proper range of frequencies i s determined for measuring a p a r t i c u l a r type of paper, the Q-meter c i r cuit may be simplified or modified to produce a less complicated instrument.  44  Aa there i s d e f i n i t e l y an urgent need at present for a rapid and accurate instrument for measuring the moisture content of a moving sheet of paper, further investigation :bf t h i s dissipation factor method i s warranted.  45  VI  LITERATURE CITED  1.  Argue, G.H. and Maass , 0. Measurement of the Variation of the D i e l e c t r i c Constant of Water with extent of Adsorption. Canadian Journal of Research, v o l . 13, section B, p. 156, 1935.  2.  Brockelsby, C F . An E l e c t r i c a l Moisture Meter. Journal of S c i e n t i f i c Instruments, v o l . 22, pp. 243-244, December, 1945.  3.  Campbell, W. Boyd, Pulp and Paper Research Institute of Canada, Montreal, Canada. Letter to Mr. R.M. Brown of U.B.C. dated July 9, 1948, i n regard to information about moisture measurement on high speed paper machines.  4.  Candee, C.N. Moisture in. Paper. Pulp and Paper Magazine of Canada, v o l . 42, No. 2, pp. 121, 122, 126, February, 1941.  5.  Culver, D.C. Measurement of Moisture i n Paper by the Resistance Method. The Paper Industry and Paper World, v o l . 23, pp. 555-561, September, 1941.  6.  E v e r i t t , W.I. Communication Engineering. New York and London, McGraw-Hill Book Company, Inc.,1937. Gardiner, S.D. Instrument to measure minute changes i n specific inductive capacity of cardboard and hence to determine i t s water content. Journal of the Society of Chemical Industry, v o l . 62, pp. 75-76, May, 1943.  7.  ;  8.  Gafton, C.G. The Drying Process i n Paper as Determined by E l e c t r i c a l Methods. Journal of the Institute .. of E l e c t r i c a l Engineers, v o l . 86, pp. 369-378, A p r i l , 1940.  9.  Golding, E.W. E l e c t r i c a l Measurements and Measuring Instruments. London, S i r Isaac Pitman and Sons, I/td., 1940.  10.  Goumeniouk, G. E l e c t r o s t a t i c Dryness Indicator. Monthly Report of Applied Science D i v i s i o n , Powell River'Company, Powell River, B . C . , January, 1949.  46  11.  Hartshorn, X.  A C r i t i c a l Resume of Recent Work on Journal of the Institute of E l e c t r i c a l Engineers, v o l . 64, pp. 1152-1190, 1926.  12.  Hartshorn, L. and Ward, W.H. The Measurements of the P e r m i t t i v i t y and Power.Factor.of D i e l e c t r i c s at Frequencies from 10 to 10° cycles. Journal of the Institute of E l e c t r i c a l Engineers, v o l . 79, pp. 597-609, 1936.  13.  Hartshorn J L . and Wilson, W. Meter. Journal of E l e c t r i c a l Engineers, pp. 403-412, October,  14.  Jones, E . H . A Moisture Meter for Textile Materials. Journal of S c i e n t i f i c Instruments, v o l . 17,No.3, pp. 55-62, March, 1940.  15.  Minton,J.P. An Investigation of D i e l e c t r i c Losses with the Cathode Ray Tube. Transactions of the American Institute of E l e c t r i c a l Engineers, v o l . 34, pp. 1627-1677, 1915.  16.  Murnaghan, F.D. Maxwell's Theory of the layer Dielectric. Transactions of the American Institute of E l e c t r i c a l Engineers, v o l . 46, pp. 132-139, February, 1927.  17.  Race, H.H. Capacitance and loss Variations with Frequency and Temperature i n Composite Insulation. Transactions of the American Institute of E l e c t r i c a l Engineers, v o l . 52, pp. 682, June, 1933.  18.  Sholl, H.A. Continuous Measurement of Sheet Moisture. Technical Association Papers, series 31, pp. 375-378, June, 1948/ Edited by MacDonald, R.G. and Bingham, R . T . , published by Technical Association of the Pulp and Paper Association, New York, N.Y.  19.  Wangsgard, A.P. and Hazen, T. The Q-Meter for D i e l e c t r i c Measurements on Polyethene and other p l a s t i c s at Frequencies up to 50 Mc. Transactions of the Electrochemical Society, v o l . 90, pp. 177-191, 1946.  20.  Wheelwright, W.B. From Paper M i l l to Pressroom. Menasha, Wisconsin, George Banta Publishing Company, 1920.  Dielectrics,  An E l e c t r i c a l Moisture the Institute of. part 2, v o l . 92, 1945.  47  21.  Whitehead, J.B. D i e l e c t r i c Absorption and Theories of D i e l e c t r i c Behavior. Journal of the American Institute of E l e c t r i c a l Engineers, v o l . 4 5 , pp. 515-524, February, 1926.  22.  Wood, H.  23.  Yager, W.A. D i e l e c t r i c Constant and D i e l e c t r i c Loss of P l a s t i c s as Related to their Compostion. Transactions of the Electrochemical Society, v o l . 74, pp. 112-129, 1928.  24.  Boonton Radio Corporation. Instructions and Manuel of Radio Frequency Measurements. Boonton Radio Corporation, Boonton, New Jersey, U.S.A.  25.  Tut t i e , W.N. The Series and P a r a l l e l Components of Impedance. The General Radio Experimenter, v o l . 20, No. 8, January, 1946.  A Moisture Content Control Equipment, i n Bernard Love 11 ed. Electronics and their Application i n Industry and Research, London, The P i l o t Press L t d . , 1947, Chap. IX, p. 382.  48  711  AOKNOWEEDGMBNT  The author wishes to express his sincere appreciation to Dr. I'. Nbakes for his continual guidance and valuable suggestions i n carrying out t h i s investigation.  49  VIII  LIST OF SYMBOLS  = Capacity of test condenser without paper d i e l e c t r i c . Cg C  Capacity of test condenser with paper d i e l e c t r i c .  =  A Z Capacities of the main and venier tuning condensers of the Q-meter.  Cg  s  Capacity of the teat condenser.  C^  =  Distributed capacitance of the inductor.  = Capacity of the i d e a l condenser. C S Capacity to resonate the inductor alone. 0  Cp - Capacity of the equivalent imperfect condenser. C  r  =  C  g  =  D  Capacity to resonate c i r e u i t with the test condenser connected. Equivalent series capacitance.  - Dissipation factor.  ^2. ' Capacitor-dial reading without paper d i e l e c t r i c . =  Dg = Capacitor-dial reading with paper d i e l e c t r i c . E  =  Voltage across the equivalent imperfect condenser.  E^  =  Known value of input voltage from the o s c i l l a t o r .  :  Total current drawn by the imperfect condenser.  I I  0  =  Current i n the condenser branch of the imperfect condenser.  I D - Current i n the resistance branch of the imperfect condenser. L TS  z  Q s  Inductance of the external inductor. Zero speed of paper.  ^1 = Speed of paper at 1100 feet per minute. Hp - Speed of paper at 1850 feet per minute.  so  <*1 r Q of the c i r c u i t without paper d i e l e c t r i c . Q *2 *c  =  «1 Q *0  Q  8  Q of the c i r c u i t with paper d i e l e c t r i c . Q, of the tuning condensers alone. Q of the external inductor alone.  =  Q of tesonant c i r c u i t with test condenser not connected.  -  Q of resonant c i r c u i t with test condenser connected.  =  GL of the test condenser alone.  9x — Q of the newsprint sample. R = 0.04 ohm non-inductive coupling r e s i s t o r . Resistance of the test condenser externally connected. R  Resistance of the tuning condenser.  0  R  e  R  i  R  L  Equivalent resistance of the p a r a l l e l impedance. =  Resistance of the i d e a l condenser. Resistance of the inductor.  *P  —  Resistance of the equivalent imperfect condenser.  s  =  Equivalent series resistance.  -  Resistance of the test condenser.  E  t V c  R  z  vtvm reading of the voltage across the condensers. Equivalent reactance of the p a r a l l e l impedance.  e  X  r  z  i  =  Reactance of the tuning condensers. Reactance of the test condenser.  t  2p =  Equivalent p a r a l l e l impedance of 2 and Z^. r  Zr z Impedance of the tuning condensers. Z  =  t  ^  s  "6*  Impedance of the test condenser. Phase angle.  - loss  angle.  51  02  if  i ••' ;i]  :.M i ;i .rHi i t i Mil. Ln  :MU  ,i •  Liijx- XL  X'M X I .bj-i x;;t  . -J- L .  ....  TV:}  ::: i  * .|;;T J , X" !' 1X.  ... 1 .  -H !- • • ; L  WM  IJ  R  -  ' ' 1.  :<:h:. Lfi'M'i  r;; r  H  w  i':'  1 ;  n i i. • L; i :i H ;; .t • X X t "n -1-  1  !::: j X !"  • ' i' * : X |  M  4  * : rF.: I iX-:x .FrX XX xtr * X I Fi4 ,;"F:r -i ;I]H XX 1-lL 4  ;  1..  ] x"  :  i!X  !-qi  L  : hi; ;.n.i  : i ir  1::.: : j T r  :  • • -r  \ \ Mf x XX t!r -I _ .-!_ ''H-i  -p::: _i'H xtFI•j-ffi- -r - -l-n-f- "Pl T H + TI -  x;  ;_;r • -L-U X l—l-L l-i  :"x  •rX  HH  :. 'r::  rxp.  !: :T  •[  .Xxh X j M Hrj'T :.H::'  ::  4i Li ,. |..  :!'.'  !! i: *"M;  ;  ;  it'-  • ft '  ;;;; i \:: ,!T  t— i  I X j1  ;  1 - HMn  iri.j  r  n:i Hi  ::: T HH Mr.  1  J  r]1 ;  •flH- : i Ft -r:.L  iX!  -i . IX _ xc*-* H-i L. L i V~X.. 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L:FF i j X i i x -h;x X x -xxt-pH XI i : ifx 4 %: :XL" :i: i 'MrM :  XL" J -t L; .  K  rriF.  n X H.H r::  V  x ;! r  ::::  .... XX X  \  ixi  i.  :jlx  L  •ijj" Xr:!" ..  TX-  !'l.: L  Xji: i-xi'  ri.L  ti"!: xM.: . - l i l t .!.,..,  i-X.  XXX T X ILL: X X " :x: L I X I rt;'  ilTI. -l-jj-i- . . L 1 . . 4  J 4 LT.  tM,.7":Px !+ti L : x  "tpi  -t • - • !-H -ii-t r - i - f • Lu . , ,-. 1 -i H . - - . . , 11. -1  "!..::"1  ! • •-•  rj-iL- P  LHXFX^-I'X  Fi IF hi ;.p -j • r- - H I - - r p ; 1 — ; - - t r r .MM L x x xfi; Fi.M: -XL .Ltrt riit - ,r :" 1irit p|. , " 'v: lifj. X 1 j' .."i-M ' H-1 .'::;] till •x 1 f t-tJ . .. ±::p rn r " L p l :i:q-; X X 1+!'!: H r LpX it X H xFt -rFf | X i Xpjl i M l i.xx TLX Pi! •11;.: ;TJ i • • - P t . . . . . X:U X • 1• -1 : rr X : " X X .Mix i-ft•\ -UP- x x x x \ Xi-H4 .,. 11. -;Xf-i- T1J.LT -\! i-r : -t-i..; •H-: i TX-1' - ;"• i- .LL: !' X-i U X t DrJt-. 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Ft Fxiix Xf. x • IMMI XffiX i i ; ; j Li 1 ' i H-t...I.— T"--i- L;!- X ; I.MS;L r JjXxTL ; i-M' :r ; i : # j - : X X : ;,*H i x : l-X i X : i l f i ® feix; IPL Tf V ' • L: J X - . -t-U-4 -.it x x ; : -iltxl. X X X r.' ; • r . i ; '. 1 'Ml r::. sxx ; X Ipi: l E p L MM IFF!:jlii^f:rTXX;:;[ * •}-  iXXf-  -' J  [i  "riix  t:n  vM  -i+!4 "!"ii.r. .;_rx  \ \  vx  14 , . ., ,  .•TIL  r  M  itt  1  -  jX iS?  -_  (  ;X|v|  it  m  i  M//  i  XL :pxx- -fl- M- "{'.1';. x.qxrxjx -i-tij f r H X H - +hT -U l- L ; i rxp -tjxf +:-H  ±t|i:  4  t  H -r v X  XFtilX ft  M  tl X  1  Mi I'M  :'. n * ''  XC  •-H- . . u : ; i .'  f x % lip XLuL_i.-U4 ' ' Tl t 1 : 1  1;  pi ;•  ; i:  ; - i r " Li"  ;.i  :": ; : r.Li r  .-•LH  r.n  •:: i  rX  :  LnliS  H i i -: H :• FX  ;pr L X "H -ni X: r X i Hi ri-X x;: I HH Mi H: X : X r : : : : Xl",. :.ri.: : X :: x H i ! :::! M'ML . . X- X r - • H i : u: • j • • : .... L I 5 X i r ; M ..: .-.-Miy/ mi y/M/ Perce ;M< eX Johte itMHH ilLi' H .ri':: H' r'  I'M  •;:: r X X  :  :-P  -!JT;. ti-!. [-  XX-: -LFF JL;XI X I ] X L L F 0 X ! "1 XiIF.  -' P t T  I TX  1  .. 1  17-. i-i'8 rax -;,i£  pr  ...  1 . , . ,  Xn TiX  X-!. n X L L X L - H  xX  j r M . •.'.•i± 'f-ft  t  .Ml:  . LIT"  L L 'IX; X L X x - X 1 . . LLX T  Xo' an- ith agi. th 3 - r e l at ion ?hi P an? '1(3 .aha.. the J? arc ^ X - SageH ibi; B.t 1T€ 0  jxp  xti':  nx HL  |'F" I X iiil:  tMx  tt!:|lf:i]-:.p;f p : r  h«  :!:: r M X L X T hx^iixxS  Wjjiiixli  53  54  56  57  X  APPENDIX •  Photographs #3 and #4 are eopied from the "Instructions and Manual of Hadio Frequency Measurement", Boonton Radio Corporation, Boonton, lew Jersey, U.S.A.  Photograph f3 ILLUSTRATING THE IMPORTANT FEATURES IN THE OPERATION A N D CONSTRUCTION OF THE TYPE 160-A Q-METER 17  27  9  6  lilM  17 16  26 27  W  9  7  13 14  8  12  Fig. 4 DESCRIPTION OF PARTS 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16  Oscillator Output Control. Osc. Out. VM. (Mult. Q By Meter). Oscillator Frequency Dial. Oscillator Frequency Indicator. Oscillator Range Switch. Q Tuning Condenser Dial. Coil Terminals. Condenser Terminals Q Voltmeter Vernier Tuning Condenser Dial. Vernier Tuning Condenser Q Tuning Condenser. Q Voltmeter Tube. Thermocouple Unit. Oscillator Range Switch Assembly. Oscillator Tuning Condenser.  17 18 19 20 21 22 23 24 25 26 27 28 29 30 31  Oscillator Tube. Thermocouple Calibrating Resistor. Oscillator Output Cable. V T V M Zero Adjust. Rectifier Tube. O N - O F F Switch. Pilot Light. H I - L O Switch. Power Unit Nameplate. Thermocouple Filter. Jack. Panel Securing Screws. Oscillator Output Control, Vernier. Dual-Voltage Switch (115-230 volts). V T V M Calibration Control.  Photograph f4 SCHEMATIC CIRCUIT DIAGRAM OF TYPE 160-A Q-METER O S C I L L A T O R  UNIT  P O W E R - V T V M  U N I T  Fig. 5  CIRCUIT CONSTANTS A N D DESCRIPTION OF PARTS 1 2  1,000 ohms. Fixed resistor 200 ohms. Fixed resistor 40.000 ohms. .-> Fixed resistor 4 Fixed resistor 2,500 ohms. 5 Fixed resistor 750 ohms. 6 Fixed resistor 200 ohms. 8,000 ohms. 7 Potentiometer 200 ohms. 8 Potentiometer 25,000 ohms. 9 Fixed resistor 24,000 ohms. 10 Fixed resistor (1%) 100 megohms. Fixed resistor 1 1 .04 ohms. 12 12a (one unit) Fixed res. • Fixed resistor 50,000 ohms. IS (small). 14 Osc. Tuning Condenser Osc. Tuning Condenser (large). 15 .0001 f . 16. Fixed Condenser .003 f. 17 Fixed Condenser 18 Fixed Condenser .005 f. (Main). 19 Q Tuning Condenser 20 Q Tuning Condenser (Vernier). 21 Terminals for test coils. 22 Terminals for test condensers. 23 Power filter condenser, 24 Oscillator grid coil. 25 Oscillator plate coil. 26 Oscillator coupling coil. u  w  tt  y  a. XOTE:  On some  oscillator  t>. XOTE:  The jxnver-line  ranges j)lug  the connections  utilizes  two Type  27 28 29 30 x  32 • 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 shown  Power filter choke. Power transformer. "HI-LO"switch. Line " O N ' - ' O F F " switch. Panel Lamp (Mazda 41, 2.5 volts). Oscillator range switch contacts. Oscillator range switch (see note). Oscillator output voltmeter. Oscillator output thermocouple. R. F. filter for osc. voltmeter. Q Voltmeter. Oscillator tube (type 102-A). Q voltmeter tube (type 101-A or 101-B). Rectifier tube (type 5W4). Fixed resistor 1,000 ohms. Fixed resistor 0.3 ohms. Thermocouple calibrating resistor. Fixed resistor 100 ohms. Fixed condenser 0.1 „f. Shielded Cable. Shielded Cable. Jack. Potentiometer 3,000 ohms. Potentiometer 1,000 ohms. Dual-Voltage Switch (115-230 volts). in dash  }AV,—\/*-am\).  lines  fuses.  are  made,  

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