Toshiba VF-nC1 instruction manual Inverters

	E6581090
	Loads that generate negative torque
	When combined with loads that generate negative torque the protection for overvoltage and
	overcurrent on the inverter will go into operation and may cause a trip. For this kind of situation,
	you must install a dynamic braking resistor, etc. that complies with the load conditions.
1	Motor with brake
	If a motor with brake is connected directly to the output side of the inverter, the brake will not

release because voltage at startup is low. Wire the brake circuit separately from the motor's main circuits.

MC2
MC1
Three-phase FLB FLC ST	CC
power supply
	MC3
MC1	MC3
MC3	MC2

B

MC1

IM

Three-phase power supply

MC2

	B
FM/	IM

P15 OUT

＋―

RY

RYMC2

Circuit configuration 1

Circuit configuration 2

In circuit configuration 1, the brake is turned on and off through MC2 and MC3. If the circuit is configured in some other way, the overcurrent trip may be activated because of the locked rotor current when the brake goes into operation. Circuit configuration 2 uses low-speed signal FM/OUT to turn on and off the brake. Turning the brake on and off with a low-speed signal may be better in such applications as elevators. Please confer with us before designing the system.

1.4.2Inverters

Protecting inverters from overcurrent

The inverter has an overcurrent protection function. However because the programmed current level is set to the inverter's maximum applicable motor, if the motor is one of small capacity and it is in operation, the overcurrent level and the electronic thermal protection must be readjusted. If adjustment is necessary, see 5-10 in Chapter 5, and make adjustments as directed.

Inverter capacity

Do not operate a large capacity motor with a small capacity (kVA) inverter even with light loads. Current ripple will raise the output peak current making it easier to set off the overcurrent trip.

Power factor improving capacitors

Power factor improving capacitors cannot be installed on the output side of the inverter. When a motor is run that has a power factor improving capacitor attached to it, remove the capacitors. This can cause inverter malfunction trips and capacitor destruction.

U

Inverter

V

W

IM

Remove the power factor improving capacitor and surge absorber

Power factor improving capacitor

Operating at other than rated voltage

Connections to voltages other than the rated voltage described in the rating label cannot be made. If a connection must be made to a power supply other than one with rated voltage, use a transformer to raise or lower the voltage to the rated voltage.

A-10