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.].
- 2nd
- Munchen: Publicis MCD, 1994
- 659 p.
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
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ENERGIA ELECTRICA DISTRIBUCION DE ENERGIA ELECTRICA SIEMENS PROTECCION ENERGIA ELECTRICA BAJO VOLTAJE