International Conference on Engineering Education for Sustainable Development (EESD) (7th : 2015)

The fundamentals and practice of essentials of application engineering concept (1) Pitis, Constantin Jun 30, 2015

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THE FUNDAMENTALS AND PRACTICE OF ESSENTIALS OF APPLICATION ENGINEERING CONCEPT (1) Constantin Pitis  BC Hydro, Power Smart, Canada  Abstract: Engineering is nothing more than planning based on knowledge instead of guesswork. In this sense everyone in design, service, maintenance, and technical sales work is his own engineer, every day. Paper presents Fundamentals of a new Concept of Five-Essentials-of-Application-Engineering (5EAE), enabling future consultants, designers, manufacturers, and end-users to consistently design and evaluate new projects or retrofits of power converters (PC) and/or industrial system drives (ISD). Paper will be focused at the component level of electro-mechanical PCs and ISDs. Another paper deals with 5EAE at the system level. Many times consultants, designers or end-users fail to “understand the conditions of motor use”. As a result, motors not performing efficiently or even failing inducing financial OPEX losses. One of the reasons could be that proposed 5EAE concept not being taught at tertiary education level. In motor case, proper application of 5EAE requires strong technical background complemented by broader knowledge in collateral fields. This is reflected by fundamentals largely presented in the paper. When selecting a motor for specific application the following 5EAE must be taken in consideration: 1) Matching the application conditions; 2) Matching the power supply conditions; 3) Matching the environmental conditions; 4) Matching the reliability conditions; and 5) Matching the business sustainability conditions. Use of 5EAE reflects a deep expertise in a single area, usually technical, complemented with a broad working knowledge of multiple areas of inquiry, establishing a professional as capable of interacting with various facets of the application. The objective of the 5EAE concept is to minimize power losses and environment impact, maximizing global efficiency and incorporating reliability indicators as a step forward in design methodology. Besides these, 5EAE produces several collateral benefits: A) An increased technical and economic performance of processes; B) The defusing of incipient energy and economic crisis; C) An improvement of environmental conditions; D) The creation of jobs in industries. The concept has already been successful applied in designing (manufacturing) various types of PCs and has created new basis–of-design for ISDs in various industries in South Africa.  Proposed concept is an ideal method to prepare practicing engineering graduates for the global economy. This approach fosters individuals with a deep technical understanding coupled with broader knowledge in the fundamentals of engineering design, innovation, business, and leadership. Consequently, 5 EAE can be used as model for improving a company’s corporate policies and/or utilities, government energy policies. Similarly, 5EAE concept could be applied at industrial systems and processes (IS&P) levels or extended to other fields of activities. 1 INTRODUCTION The paper proposes a new Concept of 5 (five) Essentials-of-Application-Engineering – 5EAE, (Pitis, 2006, Pitis 2007) which would enable engineers, consultants, designers, manufacturers, and end-users to consistently design and evaluate any design or retrofits of power converters (PC)  and/or industrial system drives (ISD). It addresses the need of syllabus opportunity by employing 5EAE concept – that is a subject not being taught in tertiary education. To date there are no specific references on this subject. The concept is focused on specific ways to think outside the box in designing and/or assessing existent EESD’15    The 7th International Conference on Engineering Education for Sustainable Development Vancouver, Canada, June 9 to 12, 2015  052-1 components of ISD. Examples are used to a large extent to show how these thinking approaches have led to better solutions in the past. In this context, such solutions tend to contribute to improvements in how we build and manage future industrial systems drives of various types. The 5EAE concept has already been successful applied in designing and manufacturing components of ISD but also integrated industrial system drives (IISD) in mining and heavy industries in South Africa (Pitis et al., 2007).  2 MARKET BARRIERS AND LIMITATIONS  The current state of industrial market is characterized by the following barriers: • The market for subject matter experts for project definition is scarce and innovation is rewarded on an hourly basis.  • Given large variety of ISD, it is difficult to apply consistent energy performance parameters as a design criteria • Additional cost requirements for system assessments and energy efficiency feasibility studies.  • Experience shows that re-engineering services work, but innovation rate may be low – as knowledge is guarded.   On the other hand from customer’s point of view, the market industry is still divided into two distinct tiers (Pitis, 2007, Pitis et al., 2010):  • Non-discerning product market, CAPEX driven, initial cost usually being the chief driver of the purchasing decision • Discerning product market - specification and OPEX driven, accepting the concept of the total cost of life cycle costing.   Approaches of designing and manufacturing ISD components are driven by this market configuration. The “non-discerning market” is price driven and the initial cost is usually the chief driver of the purchasing decision. This market is not specification driven and its focus is not, at least, on Total Ownership Costs. Purchasing activities based on the minimum prices are still prevalent. Therefore there is no special interest in promoting proposed concept. The “discerning market” has made great strides in raising the bar in terms of product specifications. The modern technical terms are frequently mentioned in purchasing specifications. This market secures business sustainability and international competitiveness. The market industry being influenced by commodity prices is also divided by the way of adopting policies on optimizing production costs structure: Short term and Long term policies. Short term policies regarding price reduction are very much influenced by current production targets. Reduced weight components on price structure are not considered between main targets of cost reduction, being not considered “low hanging fruits”. If energy costs represent small weight in production cost structure they will be neglected even from design stage of the new facility. Long term policies consider all components of production costs are subject of possible reduction. These policies could be achieved by taking advantage of commodity price fluctuations or various incentives offered by utilities or government. 3 BASICS OF FIVE ESSENTIALS OF APPLICATION ENGINEERING CONCEPT Practical applications encompass a wide range of systems with variable parameters and structure, and multiple operating modes. However industrial systems do have in common some characteristics that are addressed by use of 5EAE concept. 5EAE defines basic concepts of designing (selection) and/or assessment criteria applicable to any integrated ISD (Pitis, 2006; Pitis, 2007) This paper proposes new approach in designs/retrofits of ISD by employing the 5EAE concept – a subject not being taught in tertiary education.  Engineering is nothing more than planning based on knowledge instead of guesswork. In this sense, everyone in design, service, maintenance, and technical sales work is his (or her) own engineer, every day. Using application engineering principles requires an appreciation of the role of industrial processes in business sustainability and risk assessment. Proper selection of PC or ISD design does take some fundamental knowledge, requiring a strong technical background.  052-2 Electric Motor  Power Supply LOAD   ENVIRONMENTAL CONDITIONS RELIABILITY INDICATORS Efficiency Manufacturer & End-users Business Sustainability When selecting a motor for specific application 5 (five) essentials of what is called application engineering (5EAE) must be taken in consideration (as shown in figure 1). When selecting a PC for a specific application or when designing or retrofitting ISD, 5 (Five) Essentials of what is called Application Engineering (5EAE) must be taken in consideration (Pitis et all, 2010): • #1 EAE: Matching the application (load) conditions (electrical or mechanical load) is the most important and the most complex tenet of the five Essentials to be considered. • #2 EAE: Matching the power supply conditions means the PC must comply with incoming electrical or mechanical power conditions while also considering its influence on the incoming power. • #3 EAE: Matching PC to environmental conditions means the equipment must not be destroyed by its surroundings. Conversely, it must not, in turn, inflict environmental damages. • #4 EAE: Matching efficiency and reliability indicators enable the end-user in planning repair and maintenance (R&M) activities, preserving system performances, with reference to alteration or rapid deterioration system performance during its lifetime, and therefore minimizing operating expenses. Reliability is the reciprocal of failure, and failure is a random event mainly influenced by heat transfer and power losses, therefore efficiency can significantly influence reliability.  • #5 EAE: Matching conditions of business sustainability Using life-cycle costing methodologies to establish total cost of ownership (both capital and operating costs) promotes energy efficiency options. Business sustainability requires mutual benefits to the OEM (“premium” rewarded for value added system) and the customer.  The above essentials are graphically depicted for an electric motor as shown in figure 1 (Pitis, 2007)                   Figure 1: 5EAE required when designing (choose) an electric motor for a drive  By definition, any application design must be in full compliance with 5 EAE. The objective of the 5EAE concept is to minimize power losses and environment impact, maximizing global efficiency and incorporating its reliability indicators. It is a step forward on design methodology that minimizes production cost in terms of energy intensities of production such as kWh/production unit.  4 CASE STUDY: CONTRADICTING FIVE ESSENTIALS OF APPLICATION ENGINEERING Overseas-designed continuous miners (CM) have been imported in South Africa for use in coal mining industry. For various reasons, their declared rated performance of 40,000 tons of coal cut/month has been totally outrun in RSA (currently production figures ranging between 80,000 and 1200,000 tons of coal/month). • South African coal is much softer (allowing for CM a higher speed of the cutting process); • Higher speed process tempted the user to increase productivity with all related economic advantages  • Higher productivity enabled attractive export opportunities at competitive price (€ 40/ton of coal). 052-3  By contradicting the 5 EAE, business may become less competitive being exposed to financial risk. In this specific case losses generated per motor failure raised to double price of a new the motor! Gained experience in continuous miner designs indicates that IISD applications are available in underground mining industry (Fig. 4). Using advanced cutting technology, continuous miners cut and gather the material simultaneously, conveying to shuttle cars, hauling trucks, or to continuous haulage systems to the surface. Motor compliance with 5 EAE was consolidated within the entire CM system: • EAE #1: Load sensing on mechanical loads (and hydraulics with continuous fluid filtration & cooling), Radio remote-controlled suited for board-and-pillar operations; • EAE  #2: Compliance to mining power quality           Figure 4: Typical continuous miner machinery  • EAE #3: Explosion-proof and harsh mining conditions are met, with reduced dust generation. On-board dust filtration is accomplished by integrated scrubbers and suppression facility. Fail-safe emergency brakes on its tracks that protect hoses, protected cables and components against damage from roof and rib fall are all incorporated.        •  EAE #4: Direct sensing of electrical, mechanical, thermo-mechanical and hydraulic parameters (Torques, Voltages, Currents, Temperatures, Vibrations); health monitoring visualisation screen, Compact structure, Large range operation, High efficiency, Lean maintenance  • EAE #5: High productivity: 5 tons (x $150/t) coal/minute, used to develop longwall panels for extraction, Used for full-scale production in board-and-pillar operations, Designed to continuously cut coal and soft minerals, eliminating the need for drill and blast operations. 5 REDESIGNING ELECTRIC MOTOR USING 5EAE AND MULTI-DISCIPLINARY TECHNIQUES Millions of swimming pool motors (SPM) are running without electricity consumption being scrutinized (efficiency grading system bands starts from 1.1 kW). Swimming pool unit is attracting the owner attention only when it fails. In about 65…75 % of failures, motor replacement criterion is preferred, decision being based on initial investment. Standard SPMs are TEFC IP55/IC41 types, flange mounted fitted on pumps working in an approximate 1000 x 800 x 600 mm cubicle enclosure. The application passed homologation tests performed long time ago by South African Standards Authority. The tests have been performed on dedicated stands, at continuous running regime, with normal (clean) water. However, over the years, the application recorded unsatisfactory failure rate. Site investigations confirmed unexpected working conditions for SPMs such as (Pitis, 2009):  A. Relative frequent stop/startings and stall conditions occurring at very short intervals. B. Overload due to water contamination with dust and sand, muddy, mulch, etc. C. Condensation appearing when motors rest, due to unusual high temperature gradients. In a typical SPM, the rotor and stator electric losses represent about 55% to 65 % of the total losses. During overload and/or re-starting conditions these losses can become anything but 40…100 % higher. In many cases one or more attempts of re-start occur after overload protection initially switched off the motor. During the motor re-starts, the overload sensor may keep tripping because of its position in the motor enclosure. As a result, Condensation is most likely to appear into TEFC enclosure due to unusual high temperature gradients in specific climatic conditions, when motor stops. Condensation is detrimental 052-5 to the bearings, lubricants, insulation, and other auxiliary components. This situation (characterized by a couple of re-starts in row) is very detrimental to the motor life expectancy. Subsequently accelerated ageing effects on winding insulation and bearings are occurring (WILEC 2002). Failure rates estimation (λi) from processed statistical data on MTBF indicates life expectancy of 1.5 years. The failures of the “weak points” were found to be mostly due to thermal stresses: overheating, poor heat transfer and non-co-ordination of heat transfer and cooling of the motor components. SPMs average running time is 8 hours per day, 365 days per year with lifetime expectancy of 1.5 years (MIL, 1991, Schweitzer 1997).  Table 2 - Basic failure rates for 0.75 kW SPM (Table source: Femco file 150100069/QPS 20) Item MTBF (hours) λi x 10-6 Lifetime Notes [1/hour] expectancy Starting winding 23490 42.5 7.95 years    2nd weak point Running winding Drive bearing Rotor Non-drive bearing OLD SPM assembly 24360 21900 30960 24820 41.0 8.4 years 45.6 7.5 years 1st weak point 32.3 10.9 years 40.3 8.5 years 2101.7 1.5 years  As demonstrated above, the standard SPMs did not comply with 5EAE (Pitis, 2007). In a TEFC, B5, IP55 motor, the drive end bearing is situated in the worst position. Besides generating heat by itself from the load to be taken, bearing is receiving extra heat from adjacent components: • Heat from the winding overhangs by radiation  • Heat from the rotor via shaft by conduction • Heat from the sealing arrangement (friction of rotating shaft against the seals lips) via shaft  The drive end bearing does not take a direct cooling from the airflow generated by the external fan placed on non-drive end side of the motor. During load working time the heat dissipation of bearing is function of the drive end shield material conductibility and end shield radiating area against motor enclosure and against pump. Any extra heat transferred by thermal conductivity via drive end shield it takes a time delay due to thermal inertia (measured in a region of 10…15 minutes) to be dissipated. It is well known that fractional motors perform high slip rotor features. Electric losses on the rotor (and heat generation, too) are direct proportional to rotor slip. A critical situation (as over-heat generation) intervenes during re-start and/or overload conditions. During motor re-start (from the “hot” state) in the next 10 to 15 minutes running conditions, the bearing will be overheated (and possible collapsed) as a result of an additional thermal shock at motor re-start (superimposed on the existent “hot” condition). This thermal shock is occurring in relative short time “Δt” and may be considered as “quasi-adiabatic” (Pitis, 2005, Milton 1957) as demonstrated by the following thermo-dynamic heat transfer calculations.             Figure 5 - Basic graph of the overheat flux transferred via shaft (thermal conductivity)  The new design target was to transform existent low efficiency SPMs in an energy efficient electric motor without major alteration of the main components. Has been also demonstrated that SPM failure rate is function of thermal ageing effect. That means the process of heat transfer and evacuation has to be addressed before any changing of SPM electromagnetic design. The designed target was imposed by the 5EAE with special references to specific conditions of the mass production technological process and HS: As @ Tr Cold surface  As@Tb=40°C  X=0.1m Average surface “As” Temp. Gradient: ΔT/X=(Tr-Tb) / X  R 052-6 business sustainability. The new design matched the load conditions (the motor has to run at same rated speed); therefore impeller performances matched motor performances (compliance to essential one). Reducing electrical loading of electromagnetic design enabled a better motor behavior in different conditions of the power supply (compliance to essential two). The design structure complies with environmental conditions required by application (compliance to essential three). Ageing effect was suppressed by reducing thermal stresses. According to very conservative estimations of components failure rate of the new SPM “Ev” predicted lifetime is 2.6 times bigger than standard motors (compliance to essential four). Estimations have been done according to Montsinger and Dakin formulas using Svante Arrhenius chemical rate equation (Wilec, 2010). Additional endurance tests performed on stands simulating accelerated ageing conditions confirmed the results. Lifetime expectancy was increased to 3.1 years (Pitis, 2009). For the new designed 0.75 kW “Ev” swimming pool motor the efficiency domains have been moved up about 12 %.  Regarding compliance to essential five, the design imposed minor changes of technological process occurred at reduced supplementary expenses, production costs being consistently reduced. The following steps have been taken during redesigning activity of the “Evolution” motor [5] to increase its efficiency: Mechanical alignment on radial and axial directions between stator and the rotor; Space for winding overhangs; Air flow guidance (with reduced turbulence and aerodynamic resistance); Suitable fitting for the casing. Tooling maintenance interval was shortened. Lamination processing was improved. Winding specifications were simplified. Casing, cooling system (fan cowl) and rotor costs were considerably reduced. Labor cost reduction in winding and assembly process Assembly processes cost overall reduction by 20%. An overall 11 % in cost reduction has been recorded. Motors performances were confirmed on calibrated dynamometer as shown in Fig. 4 (Frahm et. all, 2005).             Figure 6: Dynamometer tests on SPM (Source FEMCO Patent 150100069/QPS 20 – South Africa)  The improvements of the new designed motor performances have been validated by in-house tests. A 0.75 kW SPM has been chosen as a typical example to be presented in this paper. The improvements of the efficiency domains for a 0.75 kW “Evolution” versus standard motors are shown in Fig. 5.                 Figure 7: Efficiency domain of 1 hp SPM (Source FEMCO Patent 150100069/QPS 20 – South Africa) SPM loaded on dynamometer       Power analyzer  Voltage regulator  Computerized acquisition data system with    25 %      50 %     75 %      100 %    125  Standard 0.75 kW SPM efficiencies  New SPM “Ev” 0.75 kW efficiencies  Load [%] 85  80  75  70  65  60 Efficiency % 052-7  Endurance tests on real conditions have been performed on multiple samples using a special stand and test procedure as shown in Fig. 7. The stand was designed to simulate various load and environmental conditions including: • Continuous operation stabilizing the temperature of the motor components • Various temperature ambient conditions • Various values of specific gravity of the fluid • Overload conditions (up to 180%) monitoring the temperature rise of various components • Special re-start tests from “hot” conditions monitoring the temperature rise of the components 6 CONCLUSIONS There is a large variety of Industrial System Drives (ISD) requiring sustainable and consistent approach for retrofit and new design options. Based on previous South African experience, the author presents how new concept of 5 Essentials of Application Engineering (5 EAE) can be used to set up basics of a new design methodology for industrial applications. The concept enables end-users and utility programs to consistently evaluate any power converter or ISD. 5 EAE enables consultants and customers to make consistent decisions on industrial system drive design or on selection of any power converter. Examples are used to a large extent to show how these thinking approaches have led to better solutions in the past. It was demonstrated that a multidisciplinary approach has to be considered when re-designing motors to a higher efficiency. This exercise proves that statistical probabilistic methods might revolutionize the physical shape of a product.  Similarly, 5EAE concept could be applied at industrial systems and processes (IS&P) levels or extended to other fields of activities. References  R. Frahm, A. Niekerk, A. Nola, C.D. Pitis, “A Swimming Pool Electric Motor”, Patent PA 138282/P, Spoor & Fisher, Johannesburg, Jan. 2005. MIL-Military Handbook, Reliability Prediction of Electronic Equipment, MIL-HDBK-217F, USA, Dec. 1991 Mitton, R.G., HEAT, J.M.Dent & Sons Ltd, London, 1957, pp. 252…277. Pitis, C., 2005, “Thermo-dynamic calculations on over-temperature protection of equipment”, VECTOR, South Africa, April 2005, pp30…33,,  Pitis, C., 2006, The Global Concept of Efficiency – A New Concept Part 1, Electricity + Control, South Africa, Dec. 2006, Pitis, C. 2007, The Global Concept of Efficiency: The Role of Policy, Part 2, Electricity + Control, South Africa, pp.6–14, March 2007, Available: Pitis, C. Rensburg, J, 2007, A new approach to the efficiency concept in South African Industry, Journal of Energy in Southern Africa, JESA Proceedings, Vol. 18, No. 1, February 2007, Cape Town, South Africa, pp 51 – 63, Pitis, C., 2007, Novel Method of Improving Squirrel Cage Induction Motor Performance by using Mixed Conductivity Fabricated Rotors (MCFR), PhD Thesis, North West University, South Africa, June 2007, Pitis, C., “Case Study of Using Multidisciplinary Techniques to Redesign Electric Motors”, IEEE – IEMDC2009, International Electric Machines and Drives Conference, IEMDC09, Miami, Florida May 2009  Pitis, C. Groza, V., 2010, Using General Efficiency Concept in Selection Decisions of Dedicated Equipments, paper 27, IEEE – EPEC 2010, Halifax, Canada,,  Schweitzer, E. O., Reliability Analysis of Transmission Protection using Fault tree Methods, Schweitzer Engineering Labs, Inc.,, Pullman, WA, USA, 1997 USA Dept. of Army, 2007, Reliability/Availability of Electrical & Mechanical Equipments  WILEC, “Thermal Life Predictions on Motor Insulation”, WILEC ©, Johannesburg, South Africa, May 2002. 052-8 


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