User Manual

ManualsBrandsRockwell Automation ManualsEquipmentLow-Voltage Switchgear and Controlgear

0 Table of contents

0 Table of contents.................................................................................................. 0-5

1 Load characteristics and utilization categories................................................. 1-1

1.1 Utilization categories simplify the selection of devices ................................... 1-1

1.2 Electrical heating devices.................................................................................... 1-4

1.3 Lamps and illumination equipment .................................................................... 1-4

1.3.1 Incandescent lamps................................................................................................ 1-4

1.3.1.1 Halogen lamps........................................................................................................ 1-4

1.3.2 Discharge lamps..................................................................................................... 1-4

1.4 Transformers......................................................................................................... 1-5

1.5 Reactive power compensation and switching of capacitors............................ 1-6

1.5.1 Reactive power compensation................................................................................ 1-6

1.5.1.1 Individual compensation ......................................................................................... 1-6

1.5.1.2 Group compensation .............................................................................................. 1-7

1.5.1.3 Central compensation............................................................................................. 1-7

1.5.2 Switching of capacitors........................................................................................... 1-7

1.5.2.1 Switching-on single capacitors ............................................................................... 1-8

1.5.2.2 Switching of long, screened lines ........................................................................... 1-8

1.5.2.3 Switching capacitors of central compensation units ............................................... 1-8

1.6 Control circuits, semiconductor load and electromagnetic load..................... 1-9

1.7 Three-phase asynchronous motors.................................................................... 1-9

1.7.1 Principle of operation.............................................................................................. 1-9

1.7.1.1 Slip-ring motors..................................................................................................... 1-11

1.7.1.2 Squirrel-cage induction motors............................................................................. 1-12

1.7.1.2.1 High efficiency motors .......................................................................................... 1-14

1.7.1.3 Influence of the voltage across the windings........................................................ 1-15

1.7.1.4 Performance of squirrel-cage induction motors with changing frequency ............ 1-16

2 Switching tasks and selecting the appropriate switchgear.............................. 2-1

2.1 Electrical equipment complying with standards and matching

the application requirements............................................................................... 2-1

2.2 Basic switching tasks and criteria for device selection ................................... 2-1

2.2.1 Device types ........................................................................................................... 2-2

2.2.1.1 Disconnectors (isolating switches).......................................................................... 2-2

2.2.1.2 Load switches......................................................................................................... 2-3

2.2.1.3 Switch disconnectors.............................................................................................. 2-3

2.2.1.4 Circuit breakers....................................................................................................... 2-3

2.2.1.5 Supply disconnecting devices................................................................................. 2-3

2.2.1.6 Supply disconnecting EMERGENCY STOP devices.............................................. 2-4

2.2.1.7 Summary supply disconnect and EMERGENCY STOP devices............................ 2-5

2.2.1.8 Fuses...................................................................................................................... 2-5

2.2.1.9 Devices for thermal protection................................................................................ 2-5

2.2.1.10 Contactors .............................................................................................................. 2-5

2.3 Parameters for the correct selection and sizing................................................ 2-5

2.3.1 Rated isolation voltage U

....................................................................................... 2-7 U

2.3.2 Rated operational voltage U

, rated operational current I

and utilization category 2-7 U

2.3.3 Rated impulse withstand voltage U

imp

..................................................................... 2-7 U

2.3.4 Short-circuit withstand capacity and short-circuit protection................................... 2-9

2.3.4.1 Joule integral I

t .................................................................................................... 2-10

2.3.4.2 Cut-off current I

................................................................................................... 2-10

2.3.4.3 Rated short-time withstand current l

................................................................. 2-10

LVSAM-WP001A-EN-P - April 2009

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