Installation Of A Magnetic Contactor - Toshiba TOSVERT VF-AS1 Instruction Manual

10. 2

Installation of a magnetic contactor

If using the inverter without installing a magnetic contactor (MC) in the primary circuit, use an MCCB (with a power
cutoff device) to open the primary circuit when the inverter protective circuit is activated.
If using a braking resistor or braking resistor unit, install a magnetic contactor (MC) or no-fuse breaker with a power
cutoff device to the power supply of the inverter, so that the power circuit opens when the failure detection relay (FL) in
the inverter or the external overload relay is activated.
Magnetic contactor in the primary circuit
To detach the inverter from the power supply in any of the following cases, insert a magnetic contactor (primary-side
magnetic contactor) between the inverter and the power supply.
(1) If the motor overload relay is tripped
(2) If the protective detector (FL) built into the inverter is activated
(3) In the event of a power failure (for prevention of auto-restart)
(4) If the resistor protective relay is tripped when a braking resistor or braking resistor unit is used
When using the inverter with no magnetic contactor (MC) on the primary side, install a no-fuse breaker with a voltage
tripping coil instead of an MC and adjust the no-fuse breaker so that it will be tripped if the protective relay referred to
above is activated. To detect a power failure, use an undervoltage relay or the like.
Power supply
Note on wiring
• When frequently switching between start and stop, do not use the magnetic contactor on the primary side as an
on-off switch for the inverter.
Instead, stop and start the inverter by using terminals F and CC (forward run) or R and CC (reverse run).
• Be sure to attach a surge killer to the exciting coil of the magnetic contactor (MC).
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.
Note 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.
MCCB MC
R/L1
S/L2
T/L3
Example of connection of a magnetic contactor in the primary circuit
J-3
Moter
U/T1
IM
V/T2
W/T3
Operation preparation
ST
Forward
F
R Reverse
CC
E6581301
10