Electrical Insulation for Rotating Machines

A fully expanded new edition documenting the significant improvements that have been made to the tests and monitors of electrical insulation systems

Electrical Insulation for Rotating Machines: Design, Evaluation, Aging, Testing, and Repair, Second Edition covers all aspects in the design, deterioration, testing, and repair of the electrical insulation used in motors and generators of all ratings greater than fractional horsepower size. It discusses both rotor and stator windings; gives a historical overview of machine insulation design; and describes the materials and manufacturing methods of the rotor and stator winding insulation systems in current use (while covering systems made over fifty years ago). It covers how to select the insulation systems for use in new machines, and explains over thirty different rotor and stator winding failure processes, including the methods to repair, or least slow down, each process. Finally, it reviews the theoretical basis, practical application, and interpretation of forty different tests and monitors that are used to assess winding insulation condition, thereby helping machine users avoid unnecessary machine failures and reduce maintenance costs.

Electrical Insulation for Rotating Machines:

• Documents the large array of machine electrical failure mechanisms, repair methods, and test techniques that are currently available
• Educates owners of machines as well as repair shops on the different failure processes and shows them how to fix or otherwise ameliorate them
• Offers chapters on testing, monitoring, and maintenance strategies that assist in educating machine users and repair shops on the tests needed for specific situations and how to minimize motor and generator maintenance costs
• Captures the state of both the present and past "art" in rotating machine insulation system design and manufacture, which helps designers learn from the knowledge acquired by previous generations

An ideal read for researchers, developers, and manufacturers of electrical insulating materials for machines, Electrical Insulation for Rotating Machines will also benefit designers of motors and generators who must select and apply electrical insulation in machines.

Auteur

GREG C. STONE, PhD, is an electrical engineer working at Iris Power L.P. in Toronto, Canada (a company he helped to form). Prior to that, he worked for the Research Division of Ontario Hydro, which at that time was the largest electric power utility in North America.

IAN CULBERT currently works as a rotating machine engineer at Iris Power L.P. in Toronto, Canada. Prior to that, he was a specialist at Ontario Hydro (now Ontario Power Generation Inc.) where he provided technical support to power station project engineering, operations and maintenance staff on the design, specification, maintenance, and repair of all types of motors and standby generators. Prior to that, he was a motor designer.

EDWARD A. BOULTER, Lt. Commander (Ret.), USN Reserves, is now a consulting engineer. Previously he spent nearly forty years working as project/senior engineer and technical team leader designing machine insulation systems at General Electric.

HUSSEIN DHIRANI was a senior generator design engineer at Ontario Power Generation.

Contenu

Preface xix

Chapter 1 Rotating Machine Insulation Systems 1

1.1 Types of Rotating Machines 1

1.1.1 AC Motors 2

1.1.2 Synchronous Generators 4

1.1.3 Induction Generators 6

1.1.4 Permanent Magnet (PM) Synchronous Motors and Generators 7

1.1.5 Classification by Cooling 7

1.2 Winding Components 9

1.2.1 Stator Winding 9

1.2.2 Insulated Rotor Windings 10

1.2.3 Squirrel Cage Induction Motor Rotor Windings 11

1.3 Types of Stator Winding Construction 11

1.3.1 Random-Wound Stators 12

1.3.2 Form-Wound Stators-Coil Type 12

1.3.3 Form-Wound Stators-Roebel Bar Type 13

1.4 Form-Wound Stator Winding Insulation System Features 14

1.4.1 Strand Insulation 14

1.4.2 Turn Insulation 17

1.4.3 Groundwall Insulation 19

1.4.4 Groundwall Partial Discharge Suppression 21

1.4.5 Groundwall Stress Relief Coatings for Conventional Stators 24

1.4.6 Surface Stress Relief Coatings for Inverter-Fed Stators 27

1.4.7 Conductor Shields 29

1.4.8 Mechanical Support in the Slot 30

1.4.9 Mechanical Support in the End winding 32

1.4.10 Transposition Insulation 34

1.5 Random-Wound Stator Winding Insulation System Features 36

1.5.1 Partial Discharge Suppression in Inverter-Fed Random Windings 37

1.6 Rotor Winding Insulation System Components 38

1.6.1 Salient Pole Rotor 40

1.6.2 Round Rotors 41

1.6.3 Induction Machine Wound Rotors 43

References 45

Chapter 2 Evaluating Insulation Materials and Systems 47

2.1 Aging Stresses 49

2.1.1 Thermal Stress 49

2.1.2 Electrical Stress 50

2.1.3 Ambient Stress (Factors) 52

2.1.4 Mechanical Stress 53

2.1.5 Radiation Stress 54

2.1.6 Multiple Stresses 54

2.2 Principles of Accelerated Aging Tests 54

2.2.1 Candidate and Reference Materials/Systems 55

2.2.2 Statistical Variation 55

2.2.3 Failure Indicators 61

2.3 Thermal Endurance Tests 62

2.3.1 Basic Principles 62

2.3.2 Thermal Identification and Classification 63

2.3.3 Insulating Material Thermal Aging Test Standards 64

2.3.4 Insulation System Thermal Aging Test Standards 64

2.3.5 Future Trends 67

2.4 Electrical Endurance Tests 67

2.4.1 Proprietary Tests for Form-Wound Coils 68

2.4.2 Standardized AC Voltage Endurance Test Methods for Form-Wound Coils/Bars 69

2.4.3 Voltage Endurance Tests for Inverter-Fed Windings 70

2.5 Thermal Cycling Tests 71

2.5.1 IEEE Thermal Cycling Test 72

2.5.2 IEC Thermal Cycling Test 73

2.6 Nuclear Environmental Qualification Tests 74

2.6.1 Environmental Qualification (EQ) by Testing 75

2.6.2 Environmental Qualification by Analysis 76

2.6.3 Environmental Qualification by a Combination of Testing and Analysis 77

2.7 Multifactor Stress Testing 77

2.8 Material Property Tests 78

References 80

Chapter 3 Historical Development of Insulation Materials And Systems 83

3.1 Natural Materials for Form-Wound Stator Coils 84

3.2 Early Synthetics for Form-Wound Stator Coils 86

3.3 Plastic Films and Non-Wovens 89

3.4 Liquid Synthetic Resins 90

3.4.1 Polyesters 90

3.4.2 Epoxides (Epoxy Resins) 92

3.5 Mica 95

3.5.1 Mica Splittings 95

3.5.2 Mica Paper 96

3.5.3 Mica Backing Materials 98

3.6 Glass Fibers 99

3.7 Laminates 100

3.8 Evolution of Wire and Strand Insulations 101

3.9 Manufacture of Random-Wound Stator Coils 102

3.10 Manufacture of Form-Wound Coils and Bars 103

3.10.1 Early Systems 103

3.10.2 Asphaltic Mica Systems 103

3.10.3 Individual Coil and Bar Thermoset Systems 104

3.10.4 Global VPI Systems 105

3.11 Wire Transposition Insulation 106

3.12 Methods of Taping Stator Groundwall Insulation 107

3.13 Insulating Liners, Separators, and Sleeving 109

3.13.1 Random-Wound Stators 109

3.13.2 Rotors 110

References 110

Chapter 4 Stator Winding Insulation Systems in Current Use 111

4.1 Consolidation of Major Manufacturers 114

4.2 Description of Major Trademarked Form-Wound Stator Insulation Systems 115

References 129

Chapter 5 Rotor Winding Insulation Systems 133

5.1 Rotor Slot and Turn Insulation 134

5.2 Collector Insulation 136

5.3 End Winding Insulation and Blocking 136

5.4 Retaining Ring Insulation 137

5.5 Direct-Cooled Rotor Insulation 138

5.6 Wound Rotors 139

5.7 Superconducting Sychronous Rotors 140

References 141

Chapter 6 Rotor and Stator Laminated Cores 143

6.1 Magnetic Materials 143

6.1.1 Magnetic Fields 143

6.1.2 Ferromagnetism 143

6.1.3 Magnetization Saturation Curve 144

6.1.4 Ferromagnetic Materials 144

6.1.5 Permeability 145

6.1.6 Hysteresis Loss …