Practical Troubleshooting of Electrical Equipment and Control Circuits (eBook)

Cover 1
Contents 5
Preface 7
1 Basic principles 8
1.1 Introduction 8
1.2 Basic principles of electrical machines 19
1.3 AC power systems 26
1.4 Meters used in troubleshooting 29
2 Devices, symbols, and circuits 31
2.1 Devices and symbols 31
2.2 Electrical circuits 31
2.3 Reading and understanding electrical drawings 35
2.4 Reading and understanding ladder logic 43
2.5 Wires and terminal numbering 46
3 Basic troubleshooting principles 49
3.1 Introduction 49
3.2 Basic principles in using a drawing and meter in troubleshooting circuits 50
3.3 Checks for circuit continuity with disconnected supply 51
3.4 Checks for circuit continuity with live supply 54
3.5 Tests and methods 55
3.6 Testing devices 56
3.7 Circuits 68
3.8 Accurate wiring of circuits and connections 69
3.9 Tests for installation and troubleshooting 73
4 Troubleshooting AC motors and starters 75
4.1 Introduction 75
4.2 Fundamentals of three-phase AC motors 75
4.3 Fundamental of single-phase AC motors 85
4.4 DC motors 88
4.5 Motor enclosures 92
4.6 Motor terminal identification and connection diagram 93
4.7 Motor rating and insulation types 95
4.8 Operating a motor for forward and reverse operation 97
4.9 Motor braking methods 98
4.10 Motor testingt 107
4.11 Measurements used for a motor 113
4.12 Motor failures and methods to extend its life 113
4.13 Motor control trouble–remedy table 114
4.14 Motor starter check chart 116
5 Switches, circuit breakers and switchboards 119
5.1 Introduction 119
5.2 Switches and circuit breakers 119
5.3 Overloads and fault protection 125
5.4 Switchboards 126
5.5 Motor control center 127
6 Troubleshooting variable speed drives 128
6.1 The need for VSDs 128
6.2 Basic VSD 128
6.3 Power electronic components 130
6.4 Electrical VSDs 139
6.5 Power electronic rectifiers (AC/DC converters) 142
6.6 Gate-commutated inverters (DC/AC converters) 156
6.7 Overall protection and diagnostics 164
6.8 Installations and commissioning 167
6.9 Power supply connections and earthing requirements 170
6.10 Precautions for start/stop control of AC drives 173
6.11 Control wiring for VSDS 176
6.12 Commissioning VSDs 177
7 Troubleshooting control circuits 180
7.1 Basic control circuits 180
7.2 Ladder logic circuits 184
7.3 Two-wire control 185
7.4 Three-wire control – start/stop 186
7.5 Jog/inch circuits 187
7.6 Sequence start and stop 188
7.7 Automatic sequence starting 190
7.8 Reversing circuit 190
7.9 Plug stop and anti-plug circuits 194
7.10 Two-speed motor control 196
7.11 Overload protection 196
7.12 Troubleshooting examples 197
7.13 Troubleshooting strategies 199
7.14 Ladder logic design exercise 201
Appendix A: Units and abbreviations 202
Appendix B: Troubleshooting 203
Appendix C: Low-voltage networks 220
Index 239