￭
Main disconnecting device (Q1.1)
Depending on the configuration of the drive, the main disconnecting device of the
drive is either a switch-disconnector or a main circuit breaker. Units with a
switch-disconnector also have a main contactor.
The main disconnecting device switches the main supply to the drive on and off. To
disconnect the main supply, turn the switch-disconnector to the 0 (OFF) position, or
rack out the main breaker (whichever device is installed).
WARNING!
The main disconnecting device does not isolate the input power terminals, AC
voltage meters, or the auxiliary voltage circuit from the power line. To isolate
the auxiliary voltage circuit, open the auxiliary voltage switch (Q21). To isolate
the input power terminals and AC voltage meters, open the main breaker of
the supply transformer.
To close the main disconnecting device, auxiliary voltage must be switched on, and
the grounding switch (if present) must be open.
￭
Auxiliary voltage switch [Q21]
The auxiliary voltage switch controls the supply to the internal auxiliary voltage
transformers. The transformer feeds the control circuits inside the drive such as
cooling fans, relays and measuring equipment.
￭
Grounding (earthing) switch [Q9], optional
The grounding switch [Q9] (option +F259) connects the main AC power bus to the PE
busbar. Units with 12-pulse connection (option +A004), as well some of the largest
6-pulse types, have two switches, [Q9.1] and [Q9.2], one for each 6-pulse supply line.
To close the grounding switch, auxiliary voltage must be switched on, and the main
disconnecting device must be open.
WARNING!
The grounding switch does not ground the input power terminals of the drive
or the auxiliary (control) voltage circuits.
￭
Other devices on the door
• Voltmeter (option +G334); comes with a phase selector switch.
Note: The voltage is measured on the supply side of the main switch or breaker.
• AC current meter (option +G335) on one phase.
Operation principle and hardware description 49
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