GE Fuji Electric MICRO-SAVER AF-300, Startup Manual

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9-2 9-3
Name of peripheral
equipment
Function and application
Main peripheral equipment
WARNING
When connecting the drive to the power supply, add a recommended molded case circuit
breaker in the power supply circuit. Do not use the devices with the rated current out of the
recommenced range.
Fire could occur.
Magnetic contactor (MC) An MC can be used on both the power input and output sides of the drive. On each side, the
MC works as described below. When inserted in the output circuit of the drive, an MC can also
switch the motor drive power source between the drive output and commercial power lines.

At the power source side
Insert an MC in the power source side of the drive in order to:
1) Forcibly disconnect the drive from its power source (generally, commercial/factory power
lines) with the protection facility built into the drive, or with the terminal signal line.
2) Stop drive operation in an emergency when the drive cannot interpret the stop command
due to internal/external circuit failures.
3) Cut off the drive from the power source when the MCCB inserted in the power source side
cannot disconnect it for maintenance or inspection purposes. For this purpose only, it is
recommended that you use an MC capable of being turned on/off manually.
Note: When your system requires the motor(s) driven by the drive to be started/stopped with
the MC, the frequency of the starting/stopping operation should be no more than once per
hour. The more frequent the operation, the shorter the life of the MC and capacitor(s) used in
the intermediate DC circuit, due to thermal fatigue caused by the frequent establishment of the
current flow. If this is not necessary, start/stop the motor with the terminal commands (FWD),
(REV) and/or (HLD), or with the keypad.

At the output side
Prevents externally back-fed current from being applied to the drive power output terminals (U,
V, and W) unexpectedly. An MC should be used, for example, if a circuit that switches the motor
driving source between the drive output and commercial/factory power lines is connected to the
drive.
Note: As application of high voltage external current to the drive’s secondary (output) circuits
may damage the IGBTs, MCs should be used in the power control system circuits to switch the
motor drive power source to the commercial/factory power lines after the motor has come to a
complete stop. Also ensure that voltage is never mistakenly applied to the drive output terminals
due to unexpected timer operation, or similar.

Driving the motor using commercial power lines
MCs can also be used to switch the power source of the motor driven by the drive to a
commercial power source.
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