Switching, protection and distribution in low-voltage networks : handbook with selection criteria and planning guidelines for switchgear, switchboards and distribution systems / [coordination, Georg Haberl ; editing, Georg Schöllhorn ; authors, Petra Belzner ... et al.].

CONTENIDO
1. Specifications for low-voltage devices and switchgear assemblies 15
Nomenclature of the standards authorities 15
Low-voltage switchgear and devices 17
Summary of specifications and approvals 17
Regulations and approvals in European countries 17
Standards and approvals in the U.S.A., Canada and Australia 22
Type-tested and partially type-tested switchgear assemblies (TTA and PTTA) 26
Summary of specifications and standards 26
Construction specifications 26
Generic specifications 31
Equipping specifications 31
Erection specifications 32
Relevant DIN standards for switchgear assemblies 33
Protection of persons and material assets 33
Protection against direct contact 33
Protection against electrical shock to DIN VDE 0100 33
Protection against electrical shock, positioning of operating elements in the vicinity of parts which are dangerous to touch 34
Measures to be taken in the modification or extension of switchgear assemblies already in service "Safety separation" with low-voltage switchgear 34
Protection against indirect contact 38
Comments related to the protective measures specific to the network configuration 40
Protection by total insulation 42
Erection and connection of switch and distribution boards 53
Clearances and creepage distances 54
Equipping specifications and relevant standards 56
Main switches 57
Emergency-off apparatus 58
Safety disconnecting switches for mechanical maintenance (service/repair switches) 58
The electrical equipping of industrial machinery scheduled for export to countries outside Germany 60
Colours for pushbuttons, illuminated pushbuttons and indicator lights 62
IP degrees of protection against contact with live parts, ingress of foreign bodies and ingress of liquid 63
IP degrees of protection to DIN and IEC 63
Degrees of protection according to other national specifications 64
Operating and ambient conditions 65
Normal conditions 65
Ambient temperature 65
Altitude 65
Environmental influences 66
Parameters and pollution levels of the climate classes to IEC 721 and the Siemens standard SN 29070, part 1. 68
Protection against corrosion, type of finish for technical products 68
Decontaminability 69
Climatic operating conditions for electronic equipment 70
Abnormal conditions for transport, storage and operation 72
Arduous operating conditions 72
Influence of and radiation 72
Stressing due to vibrations and impact 73
Measures against the effects of induced vibration 73
Resistance to termites 74
Environmental acceptability 74
Suppression of radio interference 74
2. Network data and duty types 76
Network data 76
Nominal voltages and frequencies 76
Short-circuit current 79
Types of short-circuits 81
Contribution to the short-circuit current by connected motors 83
Effects of short-circuit currents 84
Diagrams for determining resistance values and short-circuit currents, computer program "KUBS" for short-circuit calculations and product selection 85
Influence of the transformers and conductors on the short-circuit current 96
Duty types 98
Continuous operation duty 98
Short-time operation duty 98
Intermittent periodic duty 99
Operation at inconsistent loading 102
3. Selection criteria for low-voltage switchgear in main circuits 104
Network and operating conditions 104
Rated voltage and rated frequency 104
Rated short-circuit strength and rated switching capacity 104
Rated currents 106
Switching tasks and conditions 106
Switching tasks 106
Disconnection 106
Off-load switching 107
On-load switching 107
Motor switching 107
Power switching, switching of shortcircuits 107
Switching of components in an electrical installation 110
Starting of low-voltage motors 111
Switching of high-voltage motors 114
Switching of capacitors 114
Switching of electric heating equipment 115
Switching of lamps in lighting installations 115
Switching of low-voltage transformers 117
Switching frequency and service life 117
Permissible switching frequency 117
Mechanical service life 118
Electrical service life 118
Selection in terms of utilization categories 118
Selection of contactors 118
Selection of load switches, disconnectors, on-load disconnectors and combination fuse switch units 121
Protection against overcurrent and excessive temperature rise 122
General functions 122
Protection against overload 122
Protection against the elects of short-circuits 123
Protection against excessive temperature rise 123
Specifications 123
Specifications for overload protection devices 123
Service factors in terms of UL and CSA specifications 124
Specifications for overcurrent protection devices 125
Specifications for temperature dependent protection devices 125
Protection devices 125
Fuses 125
Circuit-breakers 128
Line-protection (miniature) circuit-breakers 130
Overload relays 131
Thermistor motor protection devices 138
Instantaneous electromagnetic over-current relays 139
Switchgear combinations 139
Swichgear combinations with fuses 139
Switchgear combinations without fuses 141
Switchgear combinations with thermistor motor protection devices 143
Protection properties of switchgear combinations 144
Comparison between the protection properties of switchgear combinations 146
Selection of circuit-breakers for power distribution systems with or without fuses 148
Protection of plant components 150
Protection of three-phase induction motors 150
Protection of conductors and cables outside the switchgear combinations 159
Protection of transformers 160
Protection of capacitors 163
Discriminative protection (selectivity) 163
Discrimination in radial networks 164
Use of discrimination tables 172
Discrimination in meshed networks 174
Protection against overvoltage 175
Overvoltage transients associated with vacuum switchgear 175
High voltage vacuum contactors, type 3TL6, for the switching of three-phase inductive motors with slip-rings or short-circuited rotors over 1kV up to 12kV 177
Vacuum contactors, type 3TF6, for the switching of three-phase induction motors with slip-ring or short-circuited rotors up to 1000V 182
Leakage-current and earth-fault protection 183
Construction and method of operation 183
Leakage-current circuit-breakers for a.c. and pulsing d.c. leakage currents 184
Discriminative leakage-current circuit-breakers 184
Product range of Siemens leakage-current circuit-breakers and tripping devices 184
Application of low-voltage switchgear in main circuits 185
Parallel and series connection of current path assemblies 185
Application of four-pole switchgear 186
Influence of network frequency and harmonic currents on the operation of switching devices 187
Thermal load carrying capacity of the current path assemblies and conductors in dependence of the network frequency 187
Switching capacity at network frequencies other than 50 Hz 188
Contact service life 189
Tripping response of releases and relays 189
The effect of harmonic currents on the tripping response of overload releases and relays 191
Electrical operating mechanisms for switchgear 191
Use of a.c. switchgear in d.c. networks 192
Load carrying capacity of the current path assemblies 192
Contact service life 193
Direct-current switching capacity 193
Use of a.c. contactors in networks with square-wave voltages 194
Switchgear for the switching of three-phase capacitors 195
Switching of capacitors with circuit-breakers 195
Switching of capacitors with contactors 195
Switching on of single capacitors 195
Switching of capacitor banks 195
Switching of capacitors with lower power ratings 196
Selection of 3TF and 3TB contactors in terms of contact service life and utilization category 197
Selection of 3TF contactors for short-time and intermittent periodic duty 201
Selection of contactors for threephase pole-changing induction motors 204
Selection of 3TF and 3TK contactors as well as circuit-breakers for the switching of lamps 206
Switching of three-phase transformers up to 1000 V with 3TF contactors 210
Starting of three-phase induction motors with slip-ring rotors 210
3P A3 Oil-cooled starters 211
Starter and start-control switches 219
Starting of three-phase induction motors with stator-resistance starters 219
Direct-on-line starting of three-phase induction motors with type 3TW motor starters 223
A.C. semiconductor motor controllers and starters, SIKOSTART 3RW22 223
4. Selection criteria for low-voltage switchgear in auxiliary circuits 233
Operating voltages in auxiliary circuits 233
Contact reliability in the case of low-voltages 233
Voltage instability in auxiliary circuits 233
Operating conditions 234
Utilization categories to DIN VDE and IEC 234
Special considerations for the selection and the use of low-voltage switchgear in Canada and the USA 234
Short-circuit protection in auxiliary circuits 236
Short-circuit and overload protection of control transformers 237
Thermistor protection in control transformers 237
Operating conditions for low-voltage switchgear in auxiliary circuits 237
Prevention of operational down-time in contactor control systems 237
Long control conductors - problems and solutions 242
Limiting of overvoltage spikes caused by the switching off of contactors (overvoltage supresión) 248
Causes of overvoltages 248
Overvoltage suppression with RC elements 249
Overvoltage suppression with diodes 253
Overvoltage suppression with varistors 253
The use of contactor relays in safety circuits 254
Selection criteria for low-voltage control transformers 257
Operating conditions 257
Duty types 259
Transformer types 260
Application and selection of position switch es, type 3SE 266
Position switches with safety function 271
5. Installation, operation and maintenance of low-voltage switchgear 273
Installation 273
Mounting aids 273
Mounting position 274
Clearance for switching-arc gases 275
Termination 275
SIGUT termination technique 275
Tab connectors 276
Box terminals 277
Operation 277
Manual operation 277
Powered operation 279
Measures to facilitate the checking replacement of parts and maintenance work 279
Checking the condition of contact pieces in 3TF contactors; assessment criteria 280
6. Transducing sensors and signal processing systems 282
Selection criteria for BERO proximity switches 283
Inductive and capacitive proximity switch es for operating distances up to 65 mm 283
Opto-BERO photoelectric proximity switches 286
Sonar-BERO ultrasonic proximity switches 287
Electronically compatible control and signalling by low-voltage switchgear 291
Reliable operation by electronic output stages 291
Adaptation of the operating voltage tolerances 292
Overvoltage suppression 292
Contact reliability 293
Assessment criteria for electromechanical and electronic controls 297
7.Type-tested switchgear assemblies (TTA) 299
General 299
Versions and designs 299
Types of construction 302
Selection criteria 306
Switchboards in standardized design 308
Introduction 308
Standard switchboards Type 8PU 313
Transformer load centre (S) substations for up to 24 kV and 1250 kV A 320
Distribution board systems 328
8HS sheet-steel enclosed distribution boards 328
8HU sheet-steel enclosures 329
8HP insulated distribution board system 329
8PL insulated busbar trunking system (L-system) 330
8L. mounting and wiring systems for control circuits 331
8MF cubicle system for switch, distribution and control boards 332
Guidelines for project planning of low voltage switch, distribution and control boards or systems 333
General 333
8PU low-voltage switchboards 338
8HS, 8HP and 8HU distribution systems 340
8L. mounting systems for control circuits 340
Domestic and utility distribution boards 340
8GB Small distribution boards 343
8GD and 8GA STAB wall-mounting/ SIKUS floor-standing distribution board systems 344
8GA SIKUS free-standing distribution board cubicles 346
SIPRO universal system meter cabinets, meter/distribution cubicles, distribution cabinets, free-standing distribution boards 348
8MB, 8MM and 8GR cable, distribution and meter cubicles for outdoor use 350
Air-conditioning of installations, switchboards and cubicles 351
General 351 7.4.6.2 8ME78 heat exchangers 354
8MR11 filtered fans 355
8MR17 refrigeration units 356
8MR21 heating units 357
Temperature rise inside insulation material and sheet steel enclosures 358
Degrees of protection, climatic and other ambient conditions 360
Power factor correction in networks with or without harmonics 363
Basic principles 363
Types of power factor correction (re active power compensation) 365
Power factor correction of three-phase induction motors and transformers 367
Project planning 369
Voltage rise caused by capacitors 372
Compensation in networks with harmonics 373
The use of audio-frequency remote control systems 377
Range of products for power factor correction 380
Charging units for stationary standby battery installations 382
Current transformers 385
Basic designs 385
Current transformers for specific applications 386
Interposing current transformers 386
Summation current transformers 386
Thread-through (ar pin-wound) current transformers 388
Cable or busbar current transformers (split-core c.t.'s) 388
Cast resin current transformers 388
Explosion-protected current transformers and current transformers for mining applications 388
Current transformers for protection purposes 389
Current transformers for power factor correction controllers 389
Accuracy classes of current transformers 390
Secondary currents of current transformers 391
Rated output power and overcurrent factor of current transformers 391
Voltages across the secondary terminals of a current transformer 392
Selection criteria for current transformers 394
Power consumption and losses in current transformer secondary circuits 394
8. Fundamental circuit diagrams 397
General information 397
Terminal designations 397
Graphic symbols according to DIN, ANSI, BS and IEC 400
Designation of equipment, conductors and general functions 408
Circuit diagrams 410
Types of circuit diagrams 410
Making use of the fundamental circuit diagrams or modifying them 412
Switching via contactors 412
Contactors with drop-out delay unit for fluttering command signals 412
Extended (early-make / late-break) auxiliary contacts in contactors (mainly for d.c. excitation of the coils) 414
Drop-out delay units for contactors 414
Contactor safety combinations 414
Direct switching of three-phase induction motors 415
Switching on and off of three-phase induction motors 415
Switch-over of a three-phase induction motor from one supply network to another 416
Automatic sequential starting of three-phase induction motors 418
Reversing the direction of rotation of three-phase induction motors (reversing starters) 420
Switching of pole-changing threephase induction motors 422
Pole-changing three-phase induction motor with one winding (Dahlander connection), two speeds, one direction of rotation 422
Pole-changing three-phase induction motor with one winding (Dahlander connection), two speeds, two directions of rotation 424
Pole-changing three-phase induction motor with two separate windings, two speeds, one direction of rotation 426
Pole-changing three-phase induction motor with two separate windings, two speeds, two directions of rotation 428
Pole-changing three-phase induction motor with three speeds, one direction of rotation, one winding in a Dahlander connection, and one separate winding for low speed 430
Pole-changing three-phase induction motor with three speeds, one direction of rotation, one winding in a Dahlander connection, one separate winding for the intermediate speed 432
Pole-changing three-phase induction motor with three speeds, one direction of rotation, one winding in a Dahlander connection, one separate winding for high speed 434
Pole-changing three-phase induction motor with three speeds, two directions of rotation, one winding in a Dahlander connection, one separate winding for low speed 436
Pole-changing three-phase induction motor with four speeds, one direction of rotation and two separate windings 440
Starting of three-phase induction motors 444
Star-delta starting of three-phase induction motors with star contactor, delta contactor and line contactor 444
Closed transition star-delta starting of three-phase induction motors 446
Four stage star-delta starting 448
Star-delta starting of three-phase induction motors in two directions of rotation 450
Star-delta starting of three-phase induction motors with power factor correction 452
Automatic starting of three-phase squirrel-cage motors via a single-pole stator-resistor (KUSA connection) using a time relay 454
Automatic starting of three-phase induction motors via a three-pole stator-resistor using a time relay 456
Automatic starting of three-phase slip-ring motors 458
Closed transition autotransformer starting of three-phase' squirrel-cage motors (Korndéirfer connection) 460
Circuits with thermistor motor protection 462
Thermistor motor protection with positive temperature coefficient (PTC) temperature sensors 462
Thermistor motor protection for a pole-changing three-phase induction motor with two separate windings and two speeds 462
PTC thermistor motor protection for alarm and switch-off of a three-phase induction motor with six sensors via a circuit-breaker for motor protection equipped with overload and shortcircuit releases 464
Thermistor motor protection for the switching off of six three-phase induction motors via contactors 466
Thermistor motor protection with negative temperature coefficient (NTC) temperature sensors 468
Circuits with monitors 470
Circuits with speed monitors 470
Direct-on-line starting of three-phase induction motors. Stopping by reverse-current braking (plug braking) 470
Direct-on-line starting of three-phase induction motors. Stopping by reverse-current braking (plug braking).Circuit with contactor relay 472
Direct reversal of three-phase induction motors with reverse-current or plug braking in both directions of rotation 474
Circuits with conveyor belt monitors 476
Circuits of contactor control systems with pressure monitors 478
Circuits with position switches 479
Reverser circuits with position switches (e.g. gate control) 479
Position switches with indicator lights 480
Terminal blocks 482
Circuits with isolating terminal blocks for current transformers 482
Circuit-breaker terminals for auxiliary circuits 484
Circuits with leakage-current (residual-current) protective devices 486
Contents
Interface units 487
Auxiliary circuits incorporating time relays 488
Star-delta starting of three-phase induction motors with star contactor, delta contactar, line contactor and time relay 488
Functions of the motor-driven time relay 7PR4140 490
Switching of an electrical heating system using a thermostat and contactor combination 491
Stand-by power supply installations 492
Three-pole change-over fram network supply to stand-by supply using contactors (generator operation) 493
Change-over fram network supply to stand-by supply with four-pole disconnection of the distribution system via two three-pole contactors 494
Project planning and engineering aids 496
9. Appendix 499
Fundamental equations, characteristic quantities and units of electricity 499
Fundamental equations of electrical engineering 499
Characteristic quantities and units of electricity in accordance with DIN VDE and IEC 500
Differences in the IEC 157-1 and IEC 947-2 publications 502
Equation symbols and SI units International System of Units (SI) 503
Conversion of international, British and American units 507
Enclosures for electrical equipment to American and Canadian standards 512
Clima tic values, influence of temperature and thermal conduction 514
Climatic values 514
Effects of temperature and thermal conduction 514
Current carrying capacity and overcurrent protection of insulated wires, cables and busbars 516
Coordination of protection devices 517
Overload protection 517
Short-circuit protection 518
Current carrying capacity 521
Load ratings of insulated conductors at ambient temperatures of 30° to 70°C and the assignment of cable protection fuses in accordance with USA and Canadian standards 525
Thermal ratings of busbars and device terminals 527
Resistance of copper and aluminium conductors 529
Rated currents of three-phase induction motors 530
Three-phase power transformers 532
Graphic symbols and vector groups of three-phase power transformers 535
Tripping behaviour of line protection and switchgear protection devices 536
Time-current tripping characteristics of circuit-breakers, miniature circuitbreakers and overload relays 536
Pre-arcing time-current characteristics of fuses (operating classes gL/gG and aM) 536
Characteristic curves and tripping behaviour of circuit-breakers 539
Current-limiting diagrams of fuses 541
Discrimination (selectivity) between fuses and circuit-breakers 543
Short-circuit currents 546
Limiting effect of conductors and cables on short-circuit currents 546
Dynamic forces created by shortcircuit currents 547
Number of switehing operations of switehing devices subjeeted to different operating periods per day 548
International network voltages and frequencies 549
EC guidelines for low voltage equipment 555
Glossary - Brief explanations of some teehnical terms 556
Addresses of important specifieation, standards and testing bodies 643
Index 645