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4.5.7 An electrical interlock shall be provided to ensure the isolation switch does not open with
the control power transformer under load. This interlock shall be designed such that during
switch opening, the transformer secondary is disconnected prior to the opening of the switch
blades. Also, during switch closing, the switch blades must close before the secondary load is
reconnected.
4.5.8 An electrical interlock shall be provided to prevent the vacuum contactor from being closed
using external test power unless the isolation switch is fully opened and the secondary of the
normal control power transformer is disconnected from the control circuit to prevent backfeeding
the transformer.
5.
Ratings
5.1
Controllers shall be rated as follows:
5.1.1 Interrupting Ratings
5.1.2 Continuous Current Ratings
5.1.3 Horsepower Ratings - Induction Motors (Approximate)
5.1.4 Short Time Current Ratings
5.1.5 Impulse Voltage Withstand
Rev. 5, 2/16/1999
- Contactor
- Controller
N-1 Enclosure (Ventilated)
N-1 Enclosure (Non-ventilated)
N-12, 3, 3R Enclosure
N-1 Enclosure (Ventilated)
N-1 Encl. (Non-ventilated)
N-12, 3, 3R Enclosure
7.2kA @ 6.6kV Max.
50kA RMS Sym. @ 5.0kV Max.
200MVA @ 2.3kV
350MVA @ 4.0kV
400MVA @ 4.6kV
720A
650A
600A
@2.3kV@4.2kV
3000
2750
2500
4320A - 30 seconds
10,800A - 1 second
60kV
1.2 x 50 microsecond wave
5500
5000
4500
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