9-2
Name of
peripheral
equipment
Function and application
When connecting the inverter to the power supply, add a recommended
molded case circuit breaker and earth leakage circuit breaker* in the path
of power supply. Do not use the devices with the rated current out of the
recommenced range.
*With overcurrent protection
Fire could occur.
Molded case
circuit breaker
Earth leakage
circuit breaker
*
*
with overcurrent
protection
Main peripheral equipment
Magnetic
contactor (MC)
An MC can be used at both the power input (primary) and output (secondary)
sides of the inverter. At each side, the MC works as described below. When
inserted in the output circuit of the inverter, an MC can also switch the motor
drive power source between the inverter output and commercial power lines.
At the power source (primary) side
Insert an MC in the power source side of the inverter in order to:
1) Forcibly cut off the inverter from the power source (generally,
commercial/factory power lines) with the protection function built into the
inverter, or with the terminal signal line.
2) Stop the inverter operation in an emergency when the inverter cannot
interpret the stop command due to internal/external circuit failures.
3) Cut off the inverter from the power source when the MCCB inserted in the
power source side cannot cut it off for maintenance or inspection purpose.
If you are to use the MC for this purpose only, it is recommended that you
use an MC capable of turning the MC on/off manually.
Note: When your system requires the motor(s) driven by the inverter to be
started/stopped with the MC, the frequency of the starting/stopping operation
should be once or less per hour. The more frequent the operation, the shorter
operation life of the MC and capacitor/s used in the DC link bus due to thermal
fatigue caused by the frequent charging 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 (secondary) side
Prevent externally turned-around current from being applied to the inverter
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 inverter
output and commercial/factory power lines is connected to the inverter.
Note: As application of high voltage external current to the inverter's
secondary (output) circuits may break 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 inverter 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
inverter to a commercial power source.
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