A one-stop resource on how to design standard-compliant low voltage electrical systems
This book helps planning engineers in the design and application of low voltage networks. Structured according to the type of electrical system, e.g. asynchronous motors, three-phase networks, or lighting systems, it covers the respective electrical and electrotechnical fundamentals, provides information on the implementation of the relevant NEC and IEC standards, and gives an overview of applications in industry.
Analysis and Design of Electrical Power Systems: A Practical Guide and Commentary on NEC and IEC 60364 starts by introducing readers to the subject before moving on to chapters on planning and project management. It then presents readers with complete coverage of medium- and low-voltage systems, transformers, asynchronous motors (ASM), switchgear combinations, emergency generators, and lighting systems. It also looks at equipment for overcurrent protection and protection against electric shock, as well as selectivity and backup protection. A chapter on the current carrying capacity of conductors and cables comes next, followed by ones on calculation of short circuit currents in three-phase networks and voltage drop calculations. Finally, the book takes a look at compensating for reactive power and finishes with a section on lightning protection systems.
- Covers a subject of great international importance
- Features numerous tables, diagrams, and worked examples that help practicing engineers in the planning of electrical systems
- Written by an expert in the field and member of various national and international standardization committees
- Supplemented with programs on an accompanying website that help readers reproduce and adapt calculations on their own
Analysis and Design of Electrical Power Systems: A Practical Guide and Commentary on NEC and IEC 60364 is an excellent resource for all practicing engineers such as electrical engineers, engineers in power technology, etc. who are involved in electrical systems planning.
Table of Contents
Preface xv
Acknowledgments xvii
Symbols xix
Abbreviations xxvii
1 Introduction 1
2 Electrical Systems 5
2.1 High-Voltage Power Systems 5
2.2 Transformer Selection Depending on Load Profiles 9
2.3 Low-Voltage Power Systems 10
2.4 Examples of Power Systems 17
2.4.1 Example 1: Calculation of the Power 17
2.4.2 Example 2: Calculation of the Main Power Line 17
2.4.3 Example: Power Supply of a Factory 17
3 Design of DC Current Installations 21
3.1 Earthing Arrangement 21
3.2 Protection Against Overcurrent 22
3.3 Architecture of Installations 23
4 Smart Grid 25
5 Project Management 27
5.1 Guidelines for Contracting 27
5.2 Guidelines for Project Planning of Electrical Systems 28
6 Three-Phase Alternating Current 31
6.1 Generation of Three-Phase Current 31
6.2 Advantages of the Three-Phase Current System 31
6.3 Conductor Systems 32
6.4 Star Connection 36
6.5 Triangle Circuit 37
6.6 Three-Phase Power 38
6.7 Example: Delta Connection 39
6.8 Example: Star Connection 41
6.9 Example: Three-Phase Consumer 43
6.10 Example: Network Calculation 44
6.11 Example: Network 45
6.12 Example: Star Connection 47
7 Symmetrical Components 49
7.1 Symmetrical Network Operation 49
7.2 Unsymmetrical Network Operation 51
7.3 Description of Symmetrical Components 51
7.4 Examples of Unbalanced Short-Circuits 54
7.4.1 Example: Symmetrical Components 54
7.4.2 Example: Symmetrical Components 54
7.4.3 Example: Symmetrical Components 55
8 Short-Circuit Currents 57
8.1 Introduction 57
8.2 Fault Types, Causes, and Designations 60
8.3 Short-circuit with R-L Network 61
8.4 Calculation of the Stationary Continuous Short-circuit 63
8.5 Calculation of the Settling Process 64
8.6 Calculation of a Peak Short-Circuit Current 65
8.6.1 Impact Factor for Branched Networks 65
8.6.2 Impact Factor for Meshed Networks 65
8.7 Calculation of the Breaking Alternating Current 66
8.8 Near-Generator Three-Phase Short-circuit 66
8.9 Calculation of the Initial Short-Circuit Alternating Current 67
8.10 Short-Circuit Power 68
8.11 Calculation of Short-Circuit Currents in Meshed Networks 68
8.11.1 Superposition Method 68
8.11.2 Method of Equivalent Voltage Source 70
8.12 The Equivalent Voltage Source Method 72
8.13 Short-Circuit Impedances of Electrical Equipment 72
8.13.1 Network Feeders 73
8.13.2 Synchronous Machines 74
8.13.3 Transformers 75
8.13.4 Consideration of Motors 76
8.13.5 Overhead Lines, Cables, and Lines 78
8.13.6 Impedance Corrections 79
8.14 Calculation of Short-Circuit Currents 81
8.14.1 Three-Phase Short-circuits 81
8.14.2 Line-to-Line Short-circuit 82
8.14.3 Single-Phase Short-circuits to Ground 82
8.14.4 Calculation of Loop Impedance 83
8.14.5 Peak Short-Circuit Current 85
8.14.6 Symmetrical Breaking Current 85
8.14.7 Steady-State Short-circuit Current 87
8.15 Thermal and Dynamic Short-circuit Strength 87
8.16 Examples for the Calculation of Short-Circuit Currents 89
8.16.1 Example 1: Calculation of the Short-Circuit Current in a DC System 89
8.16.2 Example 2: Calculation of Short-Circuit Currents in a Building Electrical System 91
8.16.3 Example 3: Dimensioning of an Exit Cable 92
8.16.4 Example 4: Calculation of Short-Circuit Currents with Zero-Sequence Resistances 93
8.16.5 Example 5: Complex Calculation of Short-Circuit Currents 94
8.16.6 Example 6: Calculation with Effective Power and Reactive Power 97
8.16.7 Example 7: Complete Calculation for a System 101
8.16.8 Example 8: Calculation of Short-Circuit Currents with Impedance Corrections 111
8.16.9 Example: Load Voltage and Zero Impedance 113
8.16.10 Example: Power Transmission 116
9 Relays 119
9.1 Terms and Definitions 119
9.2 Introduction 119
9.3 Requirements 121
9.4 Protective Devices for Electric Networks 121
9.5 Type of Relays 122
9.5.1 Electromechanical Protective Relays 122
9.5.2 Static Protection Relays 122
9.5.3 Numeric Protection Relays 122
9.6 Selective Protection Concepts 123
9.7 Overcurrent Protection 124
9.7.1 Examples for Independent Time Relays 126
9.8 Reserve Protection for IMT Relays with Time Staggering 126
9.9 Overcurrent Protection with Direction 126
9.10 Dependent Overcurrent Time Protection (DMT) 129
9.11 Differential Relays 131
9.12 Distance Protection 133
9.12.1 Method of Distance Protection 135
9.12.2 Distance Protection Zones 135
9.12.3 Relay Plan 135
9.13 Motor Protection 138
9.14 Busbar Protection 138
9.15 Saturation of Current Transformers 140
9.16 Summary 141
10 Power Flow in Three-Phase Network 143
10.1 Terms and Definitions 143
10.2 Introduction 143
10.3 Node Procedure 145
10.4 Simplified Node Procedure 148
10.5 Newton-Raphson Procedure 151
11 Substation Earthing 155
11.1 Terms and Definitions 155
11.2 Methods of Neutral Earthing 160
11.2.1 Isolated Earthing 162
11.2.2 Resonant Earthing 163
11.2.3 Double Earth Fault 164
11.2.4 Solid (Low-Impedance) Earthing 166
11.3 Examples for the Treatment of the Neutral Point 166
11.3.1 Example: Earth Fault CurrentWhen Operating with Free Neutral Point 166
11.3.2 Example: Calculation of Earth Fault Currents 167
11.3.3 Example: Ground Fault Current of a Cable 167
11.3.4 Example: Earth Leakage Coil 168
11.3.5 Example: Arc Suppression Coil 168
11.4 Dimensioning of Thermal Strength 168
11.5 Methods of Calculating Permissible Touch Voltages 169
11.6 Methods of Calculating Permissible Step Voltages 172
11.7 Current Injunction in the Ground 172
11.8 Design of Earthing Systems 173
11.9 Types of Earth Rods 175
11.9.1 Deep Rod 175
11.9.2 Earthing Strip 175
11.9.3 Mesh Earth 176
11.9.4 Ring Earth Electrode 177
11.9.5 Foundation Earthing 177
11.10 Calculation of the Earthing Conductors and Earth Electrodes 177
11.11 Substation Grounding IEEE Std 80 178
11.11.1 Tolerable Body Current 178
11.11.2 Permissible Touch Voltages 179
11.11.3 Calculation of the Conductor Cross Section 180
11.11.4 Calculation of the Maximum Mesh Residual Current 181
11.12 Soil Resistivity Measurement 182
11.13 Measurement of Resistances and Impedances to Earth 184
11.14 Example: Calculation of a TR Station 184
11.15 Example: Earthing Resistance of a Building 186
11.15.1 Foundation Earthing REF 186
11.15.2 Ring Earth Electrode 1 RER1 187
11.15.3 Ring Earth Electrode 2 RER2 187
11.15.4 Deep Earth Electrode RET 187
11.15.5 Total Earthing Resistance RETotal 188
11.16 Example: Cross-Sectional Analysis 188
11.17 Example: Cross-Sectional Analysis of the Earthing Conductor 189
11.18 Example: Grounding Resistance According to IEEE Std 80 190
11.19 Example: Comparison of IEEE Std 80 and EN 50522 193
11.20 Example of Earthing Drawings and Star Point Treatment of Transformers 194
11.21 Software for Earthing Calculation 199
11.21.1 Numerical Methods for Grounding System Analysis 199
11.21.2 IEEE Std 80 and EN 50522 203
11.21.3 Summary 217
12 Protection Against Electric Shock 219
12.1 Voltage Ranges 221
12.2 Protection by Cut-Off orWarning Messages 222
12.2.1 TN Systems 222
12.2.2 TT Systems 224
12.2.3 IT Systems 226
12.2.4 Summary of Cut-Off Times and Loop Resistances 228
12.2.5 Example 1: Checking Protective Measures 229
12.2.6 Example 2: Determination of Rated Fuse Current 231
12.2.7 Example 3: Calculation of Maximum Conductor Length 231
12.2.8 Example 4: Fault Current Calculation for a TT System 231
12.2.9 Example 5: Cut-Off Condition for an IT System 232
12.2.10 Example 6: Protective Measure for Connection Line to a House 232
12.2.11 Example 7: Protective Measure for a TT System 233
13 Equipment for Overcurrent Protection 235
13.1 Electric Arc 235
13.1.1 Electric Arc Characteristic 235
13.1.2 DC Cut-Off 237
13.1.3 AC Cut-Off 237
13.1.3.1 Cut-Off for Large Inductances 238
13.1.3.2 Cut-Off of Pure Resistances 239
13.1.3.3 Cut-Off of Capacitances 239
13.1.3.4 Cut-Off of Small Inductances 239
13.1.4 Transient Voltage 240
13.2 Low-Voltage Switchgear 241
13.2.1 Characteristic Parameters 241
13.2.2 Main or Load Switches 242
13.2.3 Motor Protective Switches 242
13.2.4 Contactors and Motor Starters 244
13.2.5 Circuit-Breakers 244
13.2.6 RCDs (Residual Current Protective Devices) 245
13.2.7 Main Protective Equipment 248
13.2.8 Meter Mounting Boards with Main Protective Switch 249
13.2.9 Fuses 251
13.2.9.1 Types of Construction 253
13.2.10 Power Circuit-Breakers 256
13.2.10.1 Short-Circuit Categories in Accordance with IEC 60947 258
13.2.10.2 Breaker Types 259
13.2.11 Load Interrupter Switches 260
13.2.12 Disconnect Switches 260
13.2.13 Fuse Links 261
13.2.14 List of Components 261
14 Current Carrying Capacity of Conductors and Cables 263
14.1 Terms and Definitions 263
14.2 Overload Protection 264
14.3 Short-Circuit Protection 265
14.3.1 Designation of Conductors 268
14.3.2 Designation of Cables 269
14.4 Current Carrying Capacity 270
14.4.1 Loading Capacity Under Normal Operating Conditions 270
14.4.2 Loading Capacity Under Fault Conditions 271
14.4.3 Installation Types and Load Values for Lines and Cables 273
14.4.4 Current Carrying Capacity of Heavy Current Cables and Correction Factors for Underground and Overhead Installation 276
14.5 Examples of Current Carrying Capacity 280
14.5.1 Example 1: Checking Current Carrying Capacity 280
14.5.2 Example 2: Checking Current Carrying Capacity 285
14.5.3 Example 3: Protection of Cables in Parallel 290
14.5.4 Example 4: Connection of a Three-Phase Cable 293
14.5.5 Example 5: Apartment Building Without ElectricalWater Heating 294
14.6 Examples for the Calculation of Overcurrents 300
14.6.1 Example 1: Determination of Overcurrents and Short-Circuit Currents 300
14.6.2 Example 2: Overload Protection 302
14.6.3 Example 3: Short-Circuit Strength of a Conductor 303
14.6.4 Example 4: Checking Protective Measures for Circuit-Breakers 304
15 Selectivity and Backup Protection 309
15.1 Selectivity 309
15.2 Backup Protection 317
16 Voltage Drop Calculations 321
16.1 Consideration of the Voltage Drop of a Line 321
16.2 Example: Voltage Drop on a 10 kV Line 325
16.3 Example: Line Parameters of a Line 325
16.4 Example: Line Parameters of a Line 327
16.5 Voltage Regulation 328
16.5.1 Permissible Voltage Drop in Accordance With the Technical Conditions for Connection 328
16.5.2 Permissible Voltage Drop in Accordance With Electrical Installations in Buildings 329
16.5.3 Voltage Drops in Load Systems 329
16.5.4 Voltage Drops in Accordance With IEC 60364 330
16.5.5 Parameters for the Maximum Line Length 330
16.5.6 Summary of Characteristic Parameters 333
16.5.7 Lengths of Conductors With a Source Impedance 334
16.6 Examples for the Calculation of Voltage Drops 334
16.6.1 Example 1: Calculation of Voltage Drop for a DC System 334
16.6.2 Example 2: Calculation of Voltage Drop for an AC System 335
16.6.3 Voltage Drop for a Three-Phase System 336
16.6.4 Example 4: Calculation of Voltage Drop for a Distributor 338
16.6.5 Calculation of Cross Section According to Voltage Drop 338
16.6.6 Example 6: Calculation of Voltage Drop for an Industrial Plant 339
16.6.7 Example 7: Calculation of Voltage Drop for an Electrical Outlet 339
16.6.8 Example 8: Calculation of Voltage Drop for a HotWater Storage Unit 339
16.6.9 Example 9: Calculation of Voltage Drop for a Pump Facility 339
16.6.10 Example: Calculation of Line Parameters 340
17 Switchgear Combinations 343
17.1 Terms and Definitions 343
17.2 Design of the Switchgear 347
17.2.1 Data for Design 347
17.2.2 Design of the Distributor and Proof of Construction 348
17.2.3 Short-Circuit Resistance Proofing 348
17.2.4 Proof of Heating 349
17.2.5 Determination of an Operating Current 349
17.2.6 Determination of Power Losses 350
17.2.7 Determination of a Design Loading Factor RDF 350
17.2.8 Determination of an Operating Current 350
17.2.9 Check of Short-Circuit Variables 351
17.2.10 Construction and Manufacturing of the Distribution 351
17.2.11 CE Conformity 352
17.3 Proof of Observance of Boundary Overtemperatures 352
17.4 Power Losses 353
18 Compensation for Reactive Power 355
18.1 Terms and Definitions 355
18.2 Effect of Reactive Power 358
18.3 Compensation for Transformers 358
18.4 Compensation for Asynchronous Motors 359
18.5 Compensation for Discharge Lamps 359
18.6 c∕k Value 360
18.7 Resonant Circuits 360
18.8 Harmonics and Voltage Quality 360
18.8.1 CompensationWith Nonchoked Capacitors 362
18.8.2 Inductor-Capacitor Units 363
18.8.3 Series Resonant Filter Circuits 365
18.9 Static Compensation for Reactive Power 365
18.9.1 Planning of Compensation Systems 368
18.10 Examples of Compensation for Reactive Power 368
18.10.1 Example 1: Determination of Capacitive Power 368
18.10.2 Example 2: Capacitive Power With k Factor 369
18.10.3 Example 3: Determination of Cable Cross Section 369
18.10.4 Example 4: Calculation of the c∕k Value 370
19 Lightning Protection Systems 371
19.1 Lightning Protection Class 373
19.2 Exterior Lightning Protection 374
19.2.1 Air Terminal 374
19.2.2 Down Conductors 375
19.2.3 Grounding Systems 379
19.2.3.1 Minimum Length of Ground Electrodes 385
19.2.4 Example 1: Calculation of Grounding Resistances 386
19.2.5 Example 2: Minimum Lengths of Grounding Electrodes 387
19.2.6 Exposure Distances in theWall Area 387
19.2.7 Grounding of Antenna Systems 389
19.2.8 Examples of Installations 389
19.3 Interior Lightning Protection 392
19.3.1 The EMC Lightning Protection Zone Concept 392
19.3.2 Planning Data for Lightning Protection Systems 395
20 Lighting Systems 399
20.1 Interior Lighting 399
20.1.1 Terms and Definitions 399
20.2 Types of Lighting 400
20.2.1 Normal Lighting 400
20.2.2 Normal Workplace-Oriented Lighting 400
20.2.3 Localized Lighting 400
20.2.4 Technical Requirements for Lighting 401
20.2.5 Selection and Installation of Operational Equipment 401
20.2.6 Lighting Circuits for Special Rooms and Systems 402
20.3 Lighting Calculations 403
20.4 Planning of Lighting with Data Blocks 405
20.4.1 System Power 405
20.4.2 Distribution of Luminous Intensity 405
20.4.3 Luminous Flux Distribution 405
20.4.4 Efficiencies 406
20.4.5 Spacing Between Lighting Elements 407
20.4.6 Number of Fluorescent Lamps in a Room 407
20.4.7 Illuminance Distribution Curves 407
20.4.8 Maximum Number of Fluorescent Lamps on Switches 407
20.4.9 Maximum Number of Discharge Lamps Per Circuit-Breaker 408
20.4.10 Mark of Origin 408
20.4.11 Standard Values for Planning Lighting Systems 409
20.4.12 Economic Analysis and Costs of Lighting 409
20.5 Procedure for Project Planning 412
20.6 Exterior Lighting 413
20.7 Low-Voltage Halogen Lamps 415
20.8 Safety and Standby Lighting 416
20.8.1 Terms and Definitions 416
20.8.2 Circuits 417
20.8.3 Structural Types for Groups of People 417
20.8.4 Planning and Configuring of Emergency Symbol and Safety Lighting 417
20.8.5 Power Supply 421
20.8.6 Notes on Installation 422
20.8.7 Testing During Operation 422
20.9 Battery Systems 423
20.9.1 Central Battery Systems 423
20.9.2 Grouped Battery Systems 427
20.9.3 Single Battery Systems 429
20.9.4 Example: Dimensioning of Safety and Standby Lighting 432
21 Generators 435
21.1 Generators in Network Operation 437
21.2 Connecting Parallel to the Network 438
21.3 Consideration of Power and Torque 438
21.4 Power Diagram of a Turbo Generator 439
21.5 Example 1: Polar Wheel Angle Calculation 440
21.6 Example 2: Calculation of the Power Diagram 440
22 Transformer 441
22.1 Introduction 441
22.2 Core 445
22.3 Winding 446
22.4 Constructions 446
22.5 AC Transformer 446
22.5.1 Construction 446
22.5.2 Mode of Action 447
22.5.3 Idling Stress 448
22.5.4 Voltage and Current Translation 448
22.5.5 Operating Behavior of the Transformer 449
22.6 Three-phase Transformer 452
22.6.1 Construction 452
22.6.2 Windings 452
22.6.3 Circuit Groups 452
22.6.4 Overview of Vector Groups 454
22.6.5 Parallel Connection of Transformers 454
22.7 Transformers for Measuring Purposes 457
22.7.1 Current Transformers 457
22.7.2 Voltage Transformer 457
22.7.3 Frequency Transformer 458
22.8 Transformer Efficiency 459
22.9 Protection of Transformers 459
22.10 Selection of Transformers 459
22.11 Calculation of a Continuous Short-Circuit Current on the NS Side of a Transformer 461
22.12 Examples of Transformers 462
22.12.1 Example 1: Calculation of the Continuous Short-Circuit Current 462
22.12.2 Example: Calculation of a Three-phase Transformer 462
23 Asynchronous Motors 467
23.1 Designs and Types 467
23.1.1 Principle of Operation (No-Load) 468
23.1.1.1 Motor Behavior 469
23.1.1.2 Generator Behavior 469
23.1.2 Typical Speed-Torque Characteristics 469
23.2 Properties Characterizing Asynchronous Motors 471
23.2.1 Rotor Frequency 471
23.2.2 Torque 471
23.2.3 Slip 472
23.2.4 Gear System 472
23.3 Startup of Asynchronous Motors 473
23.3.1 Direct Switch-On 473
23.3.2 Star Delta Startup 474
23.4 Speed Adjustment 479
23.4.1 Speed Control by the Slip 479
23.4.2 Speed Control by Frequency 479
23.4.3 Speed Control by Pole Changing 480
23.4.4 Soft Starters 481
23.4.5 Example: Calculation of Overload and Starting Conditions 483
23.4.6 Example: Calculation of Motor Data 484
23.4.7 Example: Calculation of the Belt Pulley Diameter and Motor Power 485
23.4.8 Example: Dimensioning of a Motor 485
24 Questions About Book 487
24.1 Characteristics of Electrical Cables 487
24.2 Dimensioning of Electric Cables 487
24.3 Voltage Drop and Power Loss 488
24.4 Protective Measures and Earthing in the Low-voltage Power Systems 488
24.5 Short Circuit Calculation 488
24.6 Switchgear 489
24.7 Protection Devices 489
24.8 Electric Machines 489
References 491
Index 495
