E6581595
J-4
10
Magnetic contactor in the secondary circuit
A magnetic contactor may be installed on the secondary side to switch controlled motors or supply
commercial power to the load when the inverter is out of operation.
Notes on wiring
Be sure to interlock the magnetic contactor on the secondary side with the power supply to prevent commercial
power from being applied to the inverter output terminals.
When installing a magnetic contactor (MC) between the inverter and the motor, avoid turning the magnetic
contactor on or off during operation. Turning the magnetic contactor on or off during operation causes a current
to rush into the inverter which could lead to malfunction.
10.3 Installation of an overload relay
1)
The VF-nC3 inverter has an electronic-thermal overload protective function.
In the following cases, however, an overload relay suitable for the adjustment of the motor electronic
thermal protection level (
) and appropriate to the motor used should be installed between the inverter
and the motor.
When using a motor with a current rating different to that of the corresponding Toshiba general-purpose
motor
When operating a single motor with an output smaller than that of the applicable standard motor or more
than one motor simultaneously.
2)
When using the VF-nC3 inverter to operate a constant-torque motor, such as the Toshiba VF motor, adjust
the protection characteristic of the electronic thermal protection unit (
0
m
) to the VF motor use.
3)
It is recommended to use a motor with a thermal relay embedded in the motor coil to give sufficient
protection to the motor, especially when it runs in a low-speed range.
