Toshiba VF-nC1 Installation of a magnetic contactor, Installation of an overload relay

E6581090

10.2Installation 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.

■Magnetic contactor in the primary circuit

A magnetic contactor, if installed in the power supply circuit of the inverter, cuts off the power supply to the circuit and prevents the inverter from restarting, in the event of a power failure, a trip of the overload relay (thermal relay) or the activation of the inverter protective circuit.

In addition, if the FL contact of the failure detection relay in the VF-nC1 is connected to the operation circuit of the magnetic contactor on the primary side, the magnetic contactor (MC) will be tripped when the inverter protective circuit is activated.

		VFnC1		Thermal relay Motor
MCCB	MC	R/L1	U/T1
Power				IM
		S/L2	V/T2
supply
		T/L3	W/T3
	MC
	MC	FLB
	Surge killer		F	Forward run
		FLC	R	Reverse run
			CC
		FLA

Example of connection of a magnetic contactor in the primary circuit 10

Notes 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.

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.

10.3Installation of an overload relay

1)The VF-nC1 inverter has an electronic-thermal overload protective function. In the following cases, however, the activation level of the electronic thermal protection unit must be adjusted and an overload relay suitable for the motor 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-nC1 inverter to operate a constant-torque motor, such as the Toshiba VF motor, adjust the protection characteristic of the electronic thermal protection unit 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.

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