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Peripheral Devices
1.10.3 Power-off and magnetic contactor (MC)
(1) Inverter's primary side magnetic contactor (MC)
On the inverter's primary side, it is recommended to provide an MC for the following
purposes (refer to page 22 for selection):
1)To release the inverter from the power supply when the inverter's protective function
is activated or when the drive is not functioning (e.g. emergency stop operation).
2)When the external terminal (terminal STF or STR) is used for operation, provide an
MC in the primary side to prevent an accident caused by an automatic restart made
at power restoration after an instantaneous power failure, etc. and to ensure safety
during maintenance work. When the parameter unit is used for operation, an MC
cannot be used to make a start since an automatic restart is not made after power
restoration. Though the inverter can be stopped with the primary side MC, it is
coasted to a stop.
3)To rest the inverter for a long time.
The control power supply for inverter is always running and consumes a little power.
When stopping the inverter for a long time, switching inverter power off saves power
slightly.
4)To separate the inverter from the power supply to ensure safety of maintenance/
inspection work.
As the inverter's primary MC is used for the above purposes, select the one of class
JEM1038-AC3 for the inverter input side current when making an emergency stop
during normal operation.
(2) Handling of the inverter's secondary side magnetic contactor
In principle, a magnetic contactor provided between the inverter and motor should
not be switched from OFF to ON during operation. Doing so may cause a large
inrush current to flow, leading to a stop due to overcurrent shutoff. If an MC is
provided for such purposes as switch-over to a commercial power supply, the MC
should be switched on/off after the inverter and motor have stopped.
CAUTION
Do not start and stop the inverter frequently using a magnetic contactor. Such
operation can cause the inverter to fail. (The switching life in the inverter input
circuit is about 100,000 times).