Post on 23-Mar-2020
PETITIONERS' EXHIBIT 1122 PAGE 1 OF 12
PROCEEDINGS: ELECTRICAL ELECTRONICS INSULATION CONFERENCE
AND ELECTRICAL MANUFACTURING & COIL
WINDING CONFERENCE
CHICAGO '93
EEIC/ICWA EXPOSITION
Rosemont Convention Center • Rosemont, Illinois October 4-7, 1993
INTERNATIONAL COIL WINDING
ASSOCIATION, INC.
~ Institute of Electrical We and Electronic Engineers
'u.~l) National Electrical Manufacturers Association
IEEE Catalog Number ISBN 0-7803-0846-8 ISBN 0-7803-0847-6 ISBN 0-7803-0848-4 Library of Congress ISSN: 1071-6270
93CH3219-3 (softbound) (caseboundl (microfiche) Number 76-641188
Additional copies may be obtained from :
ISBN:
IEEE Service Center 445 Hoes Lane Piscataway, NJ 08854
0-7803-0847-6 0-7803-0848-4
ICWA PO Box 278 Imperial Beach, CA 91933 Phone: 619-575-4191 Fax: 619-575-5009
Casebound Microfiche
IEEE Catalog Number: 93CH3219-3
Library of Congress Number: ISSN 1071-6270 Serial
Copyright and Reprint Permissions: Abstracting is permitted with credit to the source. Libraries are permitted to photocopy beyond the limits of U.S. copyright law for private use of patrons those articles in this volume that carry a code in the bottom of the first page, provided the percopy fee indicated in the code is paid through the Copyright Clearance Center, 29 Congress Street, Salem, MA 01970. Instructors are permitted to photocopy isolated articles for noncommercial classroom use without fee. For other copying , reprint , or republ ication permission, write to Director, Publishing Services, IEEE, 345 East 47th Street, New York, NY 10017. All rights reserved. Copyright © 1993 by The Institute of Electrical and Electronics Engineers, Inc.
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PAGE 3 OF 12
Table of Contents
Epoxy Insulation
Tuesday, October 5, 1993, 8:30 AM
Session Director: John Bullivant - Consultant
The Effect of Electric Ageing on a Cast Epoxy 1 Insulation
Y. Li, J. Unsworth & B. Gao - University of Technology
Dynamic Mechanical Behaviours of Epoxy Insulating 7 Composites
Y. Li and J. Unsworth - University of Technology
Monitoring of Electrical Properties of Particulate 13 Filled Epoxy Resins Under Corrosive Stress
Bodo Brilhl and Lutz Niemeyer ASEA Brown Boveri Corporate Research Centre
Recent Progress in Computer Simulation Applied in 17 the Automatic Pressure Gelation (APG) Process For Epoxy Casting Systems
D. Konig, R. Reichert and I. O. Vlase - Technical University of Darmstadt, HV·Lab E. Hubler and U. MaBen - CIBA·GEIGY
Vacuum Sand - Casting System for Electric and Electronic Parts
E. Omori, M. Suzuki and K. Yasu· Hitachi Chemical
Motor Manufacturing
Tuesday, October 5, 1993, 9:00 AM
Session Director: Bill R. McCoy United Technologies Automotive
Current Technology in Stator Lacing Warren C. Brown - Link Engineering Company
New Trends in Stator Testing Donald R. Walter· Machine Products Corporation
Increasing the Efficiency of Induction Motors Dr. Michael Braun - PSW Industries
Noise Problems of Appliance Drain Pumps Ciineyt Oztiirk & Ahmet Balik~ioglu . Ar(:elik A. S.
PA46 Nylon - The Driving Material for E-Motors Jack Koenen, Lisa Krause and David Pomerantz
DSM Engineering Plastics, Inc.
25
29
33
41
45
53
ix
Coil & Transformer Manufacturing
Tuesday, October 5, 1993,9:00 AM
Session Director: James F. Lord Transformer Design & Manufacturing Consultant
Transformer Design Using Windows Paul K. Goethe and William D. Goethe
Optimized Program Service, Inc.
Multi-tasking Using Magnetic Design Analysis Software
Douglas Austin IT - Espey Mfg. & Electronics Corp.
Trickle Impregnated CoiIs Using Solvent Free, Single Part Epoxy
Steven B. Garbukas and Greg Palmer Copps Industries, Inc.
Low Pressure Encapsulation of Coils, Transformers and Electronic Assemblies with Thermosetting Liquid Molding Compound
Gene Segerson and Dr. Ronald Hunadi Thermoset Plastics, Inc.
Process Techniques
Tuesday, October 5, 1993,9:00 AM
Session Director: Francis P. Murphy· Consultant
57
65
71
73
Techniques and Thermoplastics for Encapsulating 81 High Performance Coils
James F. B. Patterson, J. Lang and M. Hozumi Du Pont Polymers
Tools for Commutator Turning 85 Dellburt Kitzel . E. C. Kitzel & Sons, Inc.
Considerations About the Influence of Different 91 Process Parameters During Vacuum Casting
Gerhard Karl Mais Wilhelm Hedrich Vakuumanlagen GmbH & Co. KG
Comparative Tracking Index of PSA Insulation for 97 Electrical Equipment Component Design Accounting to UL 1950
Leroy Herauf, Treasa Grasso and T. S. Kim 3M Electrical Specialties Div.
PAGE 4 OF 12
EASA Day Technical Session
Tuesday, October 5, 1993, 9:00 AM
Session Directors: W. Brithinee - Brithinee Electric N. FIolo - The Flolo Corp .
Motor Repair Industry Response to the Energy Policy 105 Act of 1992: A Status Report
Thomas H. Bishop, P.E. - Longo Industries
One Multi-Location Network's Approach to 109 Environmental Stewardship In the 19905
G. H. Miller and V. V. Shearin - GE Apparatus Service
Practical Approaches to ISO 9000 for 115 Small-To-Midslze Company
Paul R. Vragel - Vragel & Associates, Inc. Mike Margitan - Active Industries
What is a Commutator? 121 George Strayer - Kirkwood Commutator
Rotating Electrical Equipment, Maintenance and Repair
Theo van Vliet - General Electric Canada Inc.
Magnet Wire - NEMA Tuesday, October 5, 1993, 9:30 AM
Session Director: Leon Molloy - ALCATEL
127
NEMA Magnet Wire Technical Committee Report 133 Ken Nair - Magnetek Lighting & Electronic Products
The New MW 1000 Standard 137 Thomas J. Cussen - Rea Magnet Wire Co., Inc.
International Winding Wire Standards 141 A Status Report
Steven Darling - Elektrisola, Inc.
Evaluation of A Carbonized Foam Electrode for D.C. 147 High Voltage Continuity Testing of Magnet Wire
Donald J. Barta and Christopher M. Weidman Phelps Dodge Magnet Wire Co.
A New Mathematical Modeling Approach to NEMA 153 Magnet Wire Dimensional Standards For Fine Sizes
David A. Metzler and Everett J. Scherrer Rea Magnet Wire Company, Inc.
x
Magnet Wire - General
Tuesday, October 5, 1993, 1:30 PM
Session Director: Dennis Paure - General Electric
Nonpolluting Solid Lubrication of EnameUed Wires 165 Gerhard Boockmann and F. Fichtner - Boockmann GmbH
The Relative Solvency and Viscosity Effects of 173 CresyUc Acid Isomers on High Solids Wire Enamel
Lynn M. Wells & M. Howard Strunk, Jr. - Merichem Co.
Development and Application of New Self-Bonding 179 Magnet Wires with Self-Lubricating Properties
Masuo Suzuki, Hideo Doshita, Masahiro Koyano and Makoto Tai - Optec Dai-Jchi Denko Co., Ltd.
Development of Laser Strlppable New Heat Resistant 185 Magnet Wire
T. Maezono, A. Higashiura, F. Sano and N. Nakamura Furukawa Electric Co., Ltd., Hiratsuka R&D Lab.
Insulating Material and Assessment Part 1
Tuesday, October 5, 1993, 1:30 PM
Session Director: WiUiam A. Nesgoda - General Electric
Overview of Our Heritage 191 W. Tillar Shugg - Shugg Enterprises, Inc.
Evaluation of Impregnates Designed for All-Film 195 Power Capacitors Engineering: Electric Conduction and Breakdown
Christian Brosseau - CERMO Universite Joseph Fourier
Thermal Aging Effects on the Electrical Properties of 201 FUm and Ceramic Capacitors
Eric Overton, Eric D. Baumann and Ira T. Myers - NASA Lewis Research Center and Ahmad N. Hammoud Sverdrup Technology, Inc. NASA Lewis
PAGE 5 OF 12
A Fresh Look at Permanent Magnet Processing
Tuesday, October 5, 1993, 1:30 PM
Session Director: Earle S. Seely - Walker Scientific, Inc.
Permanent Magnets in Review 207 Roger Petrie - Tlwmas & Skinner, Inc.
Efficient Magnet Charging and Conditioning 211 Earle S. Seely - Walker Scientific Inc.
Jack M. Janicke - Magnetic Research, Inc.
Effective Magnetic Measurements . 215 Rollin J. Parker and Joseph C. Nowlan
Walker Scientific, Inc.
The Hysteresisgraph As a Quality Control Tool 221 Eric 1. Dennison - Walker Scientific Inc.
Permanent Magnet Motor Magnetizing 229 and Calibrating
James William Aydelott - Magnetic Instrwnentation Inc.
Multi-pole Magnetization of High Resolution 237 Magnetic Encoders
Yin-Jao Luo, E-Tuen Hwang and Shih-Ming Huang Servo Control Dept. - Mechanical Industry
Research Lab., Industrial Technology Research Institute
Coil Design, Winding & Assembly Considerations
Tuesday, October 5, 1993, 1:30 PM
Session Director: Joseph Pizzonia Coil Winding Equipment Co.
Toroidal con Winding Machines - Making , the Best Choice
Nadeem I. Mirza - CCW Industries
243
Precision Wire Stripping 251 John M. Cole P.E. and James C. Malloy
Kolene Corporation Jeff Riedel - Ford Motor Company
Miniature con Winding Techniques Provide 255 Reliability & Longevity to Disk Drive Components
Michael D. Branch - Storage Technology Corporation
Self-Supporting Coiis - Choosing the Best Procedures 259 Bernard F. Cecire - Spectra, Inc.
Mounting & Packaging Techniques for Toroidal 261 Devices
Harold Tischler - Torelco, Inc.
xi
High Volume Motor Manufacturing in the Automotive Sector
Tuesday, October 5, 1993, 1:30 PM
Session Director: Bill R. McCoy United Technologies Automotive
Metallurgical Aspects in High Volume 263 Copper Bonding
John G. Smeggil, Ph. D. and Elizabeth A. Rasley United Technologies Research Center
New Designs Aid Engineering Thermoplastics for 271 Small Motor Assemblies
J. J. Hanrahan, William J. Hassink and Warren E. Kenney DuPont Polymers
Epoxy Bonding of Magnets for Permanent 275 Magnet Motors
Todd Irion - Engineered Materials Systems Inc.
Commutator Turning: The Tool is Only the 281 Tip of the Solution
John N. Carter - Carter Diamond Tool, Corp.
Advanced Methods of Motor Testing 287 Jeff Jugan - Schenck Turner
Transformer Insulation
Wednesday, October 6, 1993, 8:30 AM
Session Director: Werner Heideman - EHV Weidmann
New U.L. Classification for Silicone Transformer Fluid
James L. Goudie and Sharon K. Mort Dow Coming Corporation
291
High Temperature Operating Capabilities of Silicone 297 Transformer Fluid
George A. Toskey - Dow Coming Corporation
Load Break Switching in Silicone Transformer Fluid 303 Sharon Mort and James Goudie - Dow Coming Corp.
Donald Ristuccia -ABB PowerT&D Co.
Corrosive and Non-Corrosive Sulfur in 309 Transformer Oils
T. V . Oommen - ABB Power T &D Company Inc.
New Cable for Advanced Power Transformer 313 Windings
Keith D. Bultemeier - Phelps Dodge Magnet Wire Co.
PAGE 6 OF 12
Rotating Machinery - Insulation Systems
Wednesday, October 6, 1993,8:30 AM
Session Director: J. S. Edmonds - MCM Enterprise
Inorganic Bonded Mica Paper for Commutator and High-Temperature Applications
Arthur F. Doyle and Dennis Sklarski - Essex Group Inc.
New High Voltage Insulation with Increased Thermal Conductivity
A. Lutz and Dr. Rudolf BrUtsch - Von Roll Isola, The Swiss Insulating Works Ltd. G. Liptak: and R. Schuler - ABB Drives AG
Improved Mica Groundwall Insulation Via Grafted Polymers
James D. B. Smith and Rajendar K. Sadhir Westinghouse Science and Technology Center
Preliminary Evaluation of Motor Insulation for Variable Speed Application
Robert H. Rehder - General Electric Canada, Inc.
An Improved Sleevlng Insulation for Use of VPI Form-Wound Coils
L. Gerald Landry, James H. McGean and Fabian Nunez Essex Group
Electric Field Enhancement Studies on Stator Windings with Defect Sites Using Finite-Element Computation
S. E. CherukupaUi, G. L. Halldorson and H. E. Orton PowerTech Labs B. Huggins - B. C. Hydro
Magnetics in Transformers
Wednesday, October 6, 1993,9:00 AM
Session Director: Carl R. Tufts - Consultant
317
323
329
333
337
345
Comparison of 9 Mil, 11 Mil, and 14 Mil 353 Ferro-resonant Transformer Design
Carl R. Tufts - Consultant
Trends of Power Applications - New Ferrite Materials 359 and Optimized Core Shapes
JOrgen Hess - Siemens Matsushita Components
Frequency Characteristics of Ferrite Core Inductors 369 Manikantan K. Jutty, Venkatramani Swaminathan and
Marian K. Kazirnierczuk - Wright State University
Alnico Permanent Magnets an Overview 373 Achuta S. Rao, Ph. D., Thomas & Skinner, Inc.
xii
Quality Considerations in Manufacturing Electrical Components
Wednesday, October 6, 1993,9:00 AM
Session Director: Kent Robertson - Black & Decker, Inc.
World Class Manufacturing Sudershan K. Jetley - Bowling Green State University
Joseph Catalano - Marathon Special Products
High Quality, Low Cost Assembly Using the Injected Metal Assembly Process
Dave Wawrykow - Fishertech, Div. of Fisher Gauge Ltd.
Thermal Effect on the Torque-Speed Performance of a Brushless DC Motor
Barry K. Fussell - University of New Hampshire
Robotic Visual Servoing in a Flexible Manufacturing WorkceU
Todd E. Scaggs - Wright State University
Assembly Techniques in Manufacturing Motors
Wednesday, October 6, 1993,9:00 AM
Session Director: Phil Kohlhaas 3M Electrical Specialties Division
385
397
403
413
Electrostatic Fluidized Bed - System Innovations and 419 Powder Advancements
Mark R. Strucaly - Electrostatic Technology, Inc.
Customer's Voice In Commutator Engineering 425 Manfred Hinderer - Kautt & Bux Manufacturing Co.
Reducing Motor Costs Through Chemistry 435 Charles H. Brickley - Polychem Corp.
Fundamental Process and Test Considerations in 439 Room Cure Trickle
Paul C. Dreier - Liquid Control Corporation
"Heatless Cure" - Coating of Electrical Windings 443 Thomas J. Weiss - Thomas & William Machinery Co.
PAGE 7 OF 12
Magnet Wire - Testing
Wednesday, October 6, 1993,9:30 AM
Session Director: Glen Clouse - Essex Group, Inc.
Origins of High Voltage Continuity Failures in Enamel Coated Copper Magnet Wire
Horace Pops and Julie Walker - Essex Group Inc.
Frequency Characteristic of Magnet Wires M. Hatada, S. Amano, T . Sawamoto and K. Ueda
Fujikura Ltd.
457
485
Moisture Resistance of Thin Film Electrical Insulation . 489 A Comp.arison of Test Methods
John C. Yodis and Scott K. Pearsall Schenectady International Inc.
SPC for Magnet Wire Tony Greene - Essex Group, Inc.
Magnet Wire - Freon Free Refrigerant Applications
Wednesday, October 6, 1993, 1:30 PM
Session Director: Kichizo Ito - Fujikura Ltd.
493
Responding to the CFC Challenge 495 Thomas W . Dekleva - ICI Klea
R. W. Yost ICI Americas, Inc.
Resistance of Electrical Insulating Varnish to 501 Environmentally Friendly Refrigerants
Robert A. Allen - Schenectady International Inc.
Polyester Insulation Materials, HFC Refrigerants 505 and Ester Lubricants
M. S. Sefton, S.V. Mortlock and M. A. Harding ICI Films and S. Corr and Gordon Tompsett ICI Chemicals & Polymers Ltd.
CompatibiUty of Non-Metallic Motor Components 507 with R22 & RS02 Replacement Refrigerants
S. Corr, T. W. Dekleva, P. Dowdle and Gordon Tompsett ICI Chemicals & Polymers Ltd. and John Allison, and Dr. RudolfBriltsch - Von Roll Isola
CompatibiUty of Alternative Refrigerants with Varnished Magnet Wire
Robert Doerr, Ph. D. and Stephen Kujak The Trane Company
513
xiii
Transformer Insulation
Wednesday, October 6, 1993, 1:30 PM
Session Director: Werner Heideman - EHV Weidmann
Comparison of Mechanical Strengths of Three Materiais Used as Pressure Plates in Oil-Filled Transformers
R. A. Kurz, Sr. - Custom Materials Inc.
Advantages of Corrugated Transformer Insulation James E. Vachris - Franklin Fibre-Lamitex Corp.
Development of New Insulation System for Use in Oil-Filled Transformers
Thomas M. Golner - Magnetek
Sensitivity of Identified Transfer Functions in Transformer Diagnosis
S. D. Mikkelsen, J . Bak-Jensen, B. Bak-Jensen and J. Tolstrup Sorensen - Aalborg University
Rotation Machines - Insulation Systems
Wednesday, October 6, 1993, 1:30 PM
Session Director: J . S. Edmonds - MCM Enterprise
519
525
529
533
Automated Digital Winding Test Analysis Methods 539 Stefan Schlichting - Baker Instrument Co.
Comparative Performance of Woven Glass and 545 Polyester Film Backed Micaceous Tapes for the Insulation of High Voltage A.C. Stator Windings of Rotating Electrical Machines
H. S. McNaughton GEC ALSTHOM Large Machines LId.
Verification oflnsulation Temperature Class Through 553 Weight Loss Measurements
James E. Ttmperley American Electric Power Service Corp.
Voltage Endurance Test Facility for Electric 557 Generator Stator Coils
F. T. Emery and R. F. Weddleton Westinghouse Electric Corp.
Experience Gained Performing Thermal Cycling Tests 563 Robert Rehder, Bernard Moore and Robert Draper
General Electric Canada, Inc.
PAGE 8 OF 12
Wire and Cable Insulation
Wednesday, October 6, 1993, 1 :30 PM
Session Director: Robert Gear - US!
Repeated Failures and Water Treeing In Polyethylene 569 HV Cables
Dr. Tadeusz Czaszejko - Mcnash University
The Mechanism and Behaviour of Water Treeing In 573 Polymeric Materials
W. M. Al-Hasawi - College of Technological Studies Dr. A. A. Hossam-Eldin - Alexandria University A. J. Pearmain - Queen Marry College
Morphology and Chemical£omposition of Water 579 Trees In Mineral-Filled EPR Insulation .
James Xu and Andrew Garton - University of Connecticut Electrical Insulation Research Center
Commutator Fusing
Wednesday, October 6, 1993, 1:30 PM
Session Director: Bill R. McCoy United Technologies Automotive
A Systematic Approach to Process Control In Commutator Fusing
Federico Sba1chiero - Axis SpA Geoffrey pazzanese Axis USA
Commutator Fusing and Brazing Miniature Motors to Starter Motors
Edward D. Riordan - Joyal Products Inc.
An Overview of Commutator Fusing Technology William T. Egbert and Jon S. Wells - MicaJiI, Inc.
Efficient Fusing Using AC of DC Current Eric Kirker - Odawara Automation, Inc.
Verifying Armature Fusing Quality Allan Naegeli - Electronic Systems of Wisconsin
585
591
597
601
605
xiv
Armature Balancing: Process, Standards, and Trends
Wednesday, October 6, 1993, 1:30 PM
Session Director: Stephen Reimann - Vibratech Systems
Advantages and Applications for Two Station 613 Balancing Machines
Peter A. Ehlers - Schenck Trebel
Establishing Balance Tolerances For Armatures 619 G. Hines and M. Myers - Hines Industries, Inc.
Process and Product Considerations of Armatures by 627 Metal Removal
T. Jeff Franklin ill, American Hofmann Corporation
Standardization of Balancing Methodology In Motor 631 Manufacturing
Stephen J. Reimann - Vibratech Systems
Insulation Materials and Assessment Part 2
Thursday, October 7, 1993,8:30 AM
Session Director: William A. Nesgoda - General Electric
Precision Ovens for Thermal Endurance Evaluation of 635 Electrical Insulating Material
Rudolf R. Steinhaus - BASF Lacke + Farben AG
Evaluation of Electrical Material Properties: 639 Embedment Stress Testing on Electrical Encapsulation Resins
Diana Melick, D. Browning and K. Shelton Elf Atochem North America, Inc.
An Optical Technique to Detect the Degradation of 643 Electrical Insulation
S. S. Bamji, A. T. Bulinski and J. Shen National Research Council of Canada
Polymer Concrete High Voltage Insulation: A 649 Versatile Material for the 90's and Beyond
Muthian Gunasekaran - Sekar Enterprises
Evaluation of Surface Degradation of Polymer 655 insulating Materials Related to Lea~ge Current
H. Homma, T. Takahashi, T. Taniguchi .and K. Izumi Electrical Engineering Dept., Yolwsuka Research Laboratory
PAGE 9 OF 12
Rotating Machines - Diagnostic Testing
Thursday, October 7, 1993, 8:30 AM
Session Director: James Timperley - AEP
Advantages of High Voltage DC Dielectric Tests 661 Compared with AC Tests
Alain Audoli and Jean-Louis Drorruni Electricite De France
New Technology for Partial Discharge Testing of 667 Operating Generators and Motors
Greg C. Stone - Iris Power Engineering and H. G. Sedding - Ontario Hydro
On-Line Monitoring of Partial Discharge in Rotating 673 Machine Windings & Auxiliaries Including the use of External Sensors
Y. Aksenov, M. Golovkov and V. Arsentiev - DIACS, Z. Berler, D. Kral and R. Sloss Northern States Power J. C. Bromley and W. McDermid - Manitoba Hydro
In-Service Monitoring of Stator Insulation Condition of a Large Thermal Generator
V. J. Green - FES International Ltd. A. G. Seidel Houston Lighting & Power
Advanced Methods for Continuous Insulation Condition Monitoring on Hydrogenerators
Greg C. Stone - Iris Power Engineering and James S. Edmonds - MCM Enterprise LTD.
Wire and Cable Insulation
Thursday, October 7, 1993,8:30 AM
Session Director: Robert Gear - USI
681
685
Moisture Cross-Linkable Insulation Compounds with 691 Flame-Retardant Properties
C. Mahabir and S. Haridoss - AT Plastics Inc.
The Effect of Interfacial Interaction on Charge 697 Storage in Clay Filled LDPE
Weijun Yin, John Tanaka and Dwight Damon University of Connecticut Electrical Insulation Research Center
Study on Life Estimation of Cable Insulation by Gas 703 Evolution and Oxygen Consumption During Radiation and Thermal Aging
T. Okuda, K. Kanemitsuya and K. Furukawa Mitsubishi Cable Industries, LTD., T. Yagi and T. Seguchi Japan Atomic Energy Research Institute
xv
Coil & Transformer Manufacturing
Thursday, October 7, 1993, 9:00 AM
Session Director: James F. Lord Transformer Design & Manufacturing Consultant
Computer Design of AC and DC Inductors 707 Robert Kakalec - Energy Systems Technical Services, Inc.
Joseph Hubert - Independent Consultant Energy Systems
Transformer Design for Low Cost Battery Chargers 713 Richard M. Haas - Avex Electronics Inc.
Shielding and Magnetic Field Reduction for Small and 719 Medium Size Transformers and Reactors
Harold O'Connor Espey Manufacturing & Electronics Corp.
Coil Bobbin and Encapsulated Coil Plastics for the 725 1990's
S. B. Neher, M. Lana Sheer, Ph. D. and W. E. Garrison Du Pont Polymers
Applied Quality Functions in Electrical & Coil Winding Manufacturing
Thursday, October 7, 1993, 9:00 AM
Session Director: Dr. John W. Sinn Center for Quality, Measurement & Automation, Bowling Green State University
Introduction and Overview of Statistical Process 729 Control
Dr. John W. Sinn - Bowling Green State University
Applying Machine Vision in Electrical Component 737 Manufacturing
David V. Gedeon and Topher D. Gedeon Bowling Green State University
Cause & Effect Analysis: Power Tool for Total Quality 751 J. E. Gibson - Black & Decker (U.S.) Inc.
Subject and Edition Index 755
PAGE 10 OF 12
TECHNIQUES AND THERMOPLASTICS FOR ENCAPSULATING HIGH PERFORMANCE COILS
J. F. B. Patterson J. Lang
M. Hozumi
DuPont Polymers Wilmington, Delaware
ABSTRACT
The use of thermoplastic encapsulated transformers, sensors, solenoids, motor stators and other assemblies is soaring rapidly. This is due in part to the "electronic cars" of the 1990's with their numerous requirements for corrosion resistant sensors and solenoids, in part to the continuing trend to convert mechanical control systems to electromechanical controls, and in part to environmental pressures on volatile organic compound emissions (VOCs).
Thermoplastic encapsulation can also lead to part consolidation, a reduction in assembly operations compared with traditional potting methods, and enhanced physical support against vibration and mechanical shock.
This paper reviews recent developments in thermoplastic encapsulation materials, molding techniques, and mold design for encapsulating high performance coils. It also covers recently developed encapsulation systems for UL 1446 Class F (155 C) and Class H (180 C) applications.
Figure 1: 250 and 400 W choke transformers for lighting are encapsulated with PET polyester resin.
81
INTRODUCTION
At the 1990, 1991 and 1992 ICWA conferences, we reported on the encapsulation of transformers and small coils (1,2,3). We described the basic materials and processes used in the encapsulation of sensors, solenoids, contactors, motor stators, and transformers. This paper builds on the earlier presentations with new information about work with larger transformers, test procedures for encapsulation resins, delicate sensor encapsulations, and progress toward UL 1446 Class F (155 C) and Class H (180 C) recognition for encapsulation systems.
DISCUSSION
Thermoplastic encapsulation of transformers and small coils continues to grow very rapidly. Part of the growth is due to a rapid increase in the number of sensors for automotive electronic systems. These sensors need the durability that thermoplastic encapsulation provides. Other factors in the growth of encapsulation include environmental pressures on potting processes, general requirements for improved product reliability and safety, and the need to reduce part counts and simplify assembly.
This growth has created a need for modified resins and technology for more difficult encapsulations, including transformers larger than 500 VA, delicate electronic sensors, and coils/transformers requiring thermal cycling to temperatures in the 150-200 C range.
Transformers
The injection molding techniques and thermoplastic resins for encapsulating small transformers are well established. Smaller transformers in the range of 50 to 200 VA can be encapsulated on vertical clamp molding equipment while somewhat larger transformers can be accommodated on horizontal molding equipment with
shot sizes of up to 500 grams (see Figure 1).
For transformers in the 1 kVA or larger range, encapsulation with conventional injection molding equipment becomes difficun and expensive. Molds strong enough to support heavy 2-to-3-kVA transformers. for example, are themselves extremely expensive .
Another problem with encapsulating larger transformers is the tendency for cracks to occur in the encapsulation layer at the weld lines during thermal cycling in the 150 to 200 C range. This is attributed to the differences in the coefficients of linear thermal expansion between the encapsulation resin and the metal laminations of the transformers.
To avoid the problems of cost and weld line weakness,
we turned to compression molding with moldable composite sheet. We use paper-making technology to convert glass fibers and either nylon 6,6 or PET polyester fibers into a mat. The mat is cut into sections of the desired weight, dried and heated in a convection oven, and then compression molded around the transformerto encapsulate it . Figure 2 shows the process as compared to injection molding.
Using this technique, we have successfully encapsulated 3 kVA transformers whose encapsulation layers have successfully withstood repeated thermal cycling to 200 C.
Thermal cycling testing
Thermalcycling performance is an important indication
Process Comparison
INJECTION
Pellets Convey & Dry
RAW PREPARE FOR MATERIAL ~ MOLDING
COMPRESSION
Porous Sheet Cut & Stack
PAGE 11 OF 12
•
Figure 2
82
WiL7kkD1 Screw I Barrel Injection
'-_H_E_AT_ ..... I_-l~~ I. __ M_O_L_D
_ ...
Convection Heating
Compression
of performance in actual service for many encapsulations. To test the ability of resin compositions to withstand thermal cycling, we have developed a very simple test procedure that has found wide application in qualifying resins for encapsulating sensors and solenoids.
Forthe test, a steel ferrule is encapsulated with a 0.12-in. layerof the resin being evaluated. The ferrule is 1.3 in. long and 1.26 in. in diameter, and its shoulders are sharply machined. Figure 3 shows a ferrule and encapsulations ready for testing.
The encapsulated ferrule is tested for 7 cycles of 16 hours at 150 C followed by 8 hours at 40 C. Ahhough this test is not identical to standard thermal cycling tests , it has been used successfully to screen and compare the pertormance of a number of resins.
Pan suppon
It is essential to keep a component being encapsulated proper1y aligned in the molding tool. We have found that this can be done successfully with hydraulicallydriven pins that hold the component in place while resin is injected into the mold cavity. These pins retract just before the resin becomes solid, and continuing injection pressure from the molding machine supplies molten resin to fill voids that would result from the withdrawal of the pins .
When the mold is opened, the pins are extended to eject the finished part and stay in position to support the next component to be encapSUlated.
An alternative method uses fixed pins . The voids left in the part are filled using ultrasonic welding techniques.
Progress toward Classes F (155 C) and H (180 C)
Ahhough needs for most encapsulated transformers and coils can be met with a UL 1446 Class B (130 C) insulation system recognition, there is a trend toward requiring higher temperature classes. The industry is moving toward more compact components and assemblies that operate at higher temperatures than were common in the past.
Using the steel ferrule test described above and a resin
PAGE 12 OF 12 83
Figure 3: Steel ferrule (left) is encapsulated with thermoplastics for thermal cycle testing.
with a very low dissipation factor, we have been able to produce coils that have recently received provisional Class F and Class H recognitions.
SUMMARY
Starting lrom a relatively modest beginning, thermoplastic encapsulation is finding increasing use in sophisticated wound coil applications . Advances in design, molding technology, and resin composition have extended applicat ions lor e ncapsula! ion I ar beyond the initial expectations of many people in the industry. Driven by strong economic forces, encapsulation is a growth technology for the future .
References·
(I)J. F. B. Patterson and C. N. Johnson, "Thermoplastic encapsulation of coil forms,ff presented al the International Coil Winding Association Conference. Chicago, 111., October 1990.
(2) J. F. B. Patterson, ~Advances in thermoplastic coil encapsulation ," presented at the International Coil Winding Association Conference, Boston, .Mass., October 1991 . (3) G. D. Neal, J. F. B. Patterson, B. C . Golt and J. Deeble, "Advances in thermoplastic encapsulation of transformers and small wound coils,~ presented at the International Coil Winding Association Conference , Cincinatti, Oh., September 1992.