20
NXAIR M
139-2021.9 / 07
Interlocks
7 Interlocks
7.1
Mechanical interlocks for single-busbar system
Action
Internal preconditions
Inserting the withdrawable part in the panel
Withdrawable part on the service truck
Pulling the withdrawable part out of the panel
None
Racking the withdrawable part to service position
Withdrawable part inserted and interlocked
Low-voltage connector plugged on
High-voltage door closed
Circuit-breaker in OPEN position
Feeder earthing switch in OPEN position
Plugging on the low-voltage connector
Consistent coding between connector and
withdrawable part fulfilled
Racking the withdrawable part to test position
Circuit-breaker in OPEN position
Closing the circuit-breaker
Withdrawable part in interlocked end position
(test position or service position)
Closing the circuit-breaker
Undervoltage release not electrically operated
Opening the circuit-breaker
None
Operating the feeder earthing switch
Withdrawable part in test position
Operating the busbar earthing switch
None (see note given below)
Opening the high-voltage door
Withdrawable part in test position
Closing the high-voltage door
Low-voltage connector plugged on