Fuji Electric FRENIC-ECO, Instruction Manual

Page: 232 / 246

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 ground fault circuit interrupter 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
Ground fault
circuit interrupter
*
with overcurrent
protection
Main peri
pheral
equi
pment
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 output side 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.