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Supply unit control devices
Run enable is the main control signal of the supply unit. The control program reads it
from digital input DI2. User controls the signal with an operating switch installed on
the cabinet door, typically. When the digital input DI2 is on, it is also possible to control
the Run enable signal from a control panel, through fieldbus interface, or from the
inverter unit.
Main disconnecting device [Q1]
￭
Depending on the configuration of the drive, the main disconnecting device [Q1] is
either a switch-disconnector or a main circuit breaker. Units with a switch-disconnector
also have a main contactor.
The main disconnecting device isolates the drive main circuit from the main AC power
supply. To isolate, user turns the switch-disconnector to the 0 (OFF) position, or racks
out the main breaker.
WARNING!
The main disconnecting device does not isolate the input power terminals or
AC voltage meters [P5.x], (option +G334) from the main AC power supply.
Depending on the drive configuration, also the auxiliary circuit and charging
circuit (if any) can remain non-isolated. To isolate the drive completely from
the main AC power supply, open the main breaker of the supply transformer.
WARNING!
The grounding switch [Q9] (option +F259) and the main switch-disconnecting
device [Q1] are electrically interlocked: Only one of them can be closed at a
time. The drive auxiliary control voltage must be on to close the switches.
Auxiliary voltage switch [Q21]
￭
The auxiliary voltage switch [Q21] controls the supply to the internal auxiliary circuits.
User operates the switch with a handle on the cabinet door.
Grounding switch [Q9]
￭
The grounding switch [Q9] (option +F259) connects the main AC power busbars to
the PE busbar.
To close the grounding switch, auxiliary voltage must be switched on, and the main
disconnecting device [Q1] must be open. User operates the switch with a handle on
the cabinet door.
WARNING!
The grounding switch does not ground the input power terminals of the drive
or the auxiliary (control) voltage circuits.
Charging switch [Q3] and DC switch/disconnector [Q40]
￭
The charging switch [Q3] feeds power to the charging circuit. The supply unit control
program controls the charging circuit on and off with the charging contactor [Q4]. At
the drive power up, the control program closes the contactor. After the DC link
capacitors are charged, the control program opens the contactor and starts the supply
unit.
Operation principle and hardware description 33
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