Mitsubishi Electric FR-D720S SC EC, Instruction Manual

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Connection of stand-alone option units Wiring
3 - 32
3.6 Connection of stand-alone option units
The inverter accepts a variety of stand-alone option units as required.
3.6.1 Magnetic contactors (MC)
Inverter input side magnetic contactor (MC)
On the inverter input side, it is recommended to provide an MC for the following purposes.
●
To release the inverter from the power supply when the fault occurs or when the drive is not
functioning (e.g. emergency stop operation).
When cycle operation or heavy-duty operation is performed with an optional brake resistor
connected, overheat and burnout of the discharging resistor can be prevented if a regener-
ative brake transistor is damaged due to insufficient heat capacity of the discharging resistor
and excess regenerative brake duty.
●
To prevent any accident due to an automatic restart at restoration of power after an inverter
stop made by a power failure.
●
The control power supply for inverter is always running and consumes a little power. When
stopping the inverter for an extended period of time, powering off the inverter will save power
slightly.
●
To separate the inverter from the power supply to ensure safe maintenance and inspection
work. The inverter's input side MC is used for the above purpose, select class JEM1038-
AC3MC for the inverter input side current when making an emergency stop during normal
operation.
b
CAUTION:
Incorrect connection will cause inverter damage or accident. Connect and operate the
option unit carefully in accordance with the corresponding option unit manual.
NOTE Since repeated inrush currents at power on will shorten the life of the converter circuit
(switching life is about 1,000,000 times.), frequent starts and stops of the MC must be
avoided. Turn on/off the inverter start controlling terminals (STF, STR) to run/stop the
inverter.