Toshiba Tosvert VF-AS1 - Manual (Page 32)

E6581301
A-16
1
1.4.2 Inverters
Protecting inverters from overcurrent
The inverter has an overcurrent protection function. The programmed current level is set to the inverter's maximum
applicable motor. If the motor used has a small capacity, the stall prevention level, overcurrent level and the motor
electronic thermal protection must be readjusted. If adjustment is necessary, refer to Section 5.14, 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 correction capacitor
Power factor correction capacitors cannot be installed on the output side of the inverter. When a motor is run that
has a power factor correction capacitor attached to it, remove the capacitors. This can cause inverter malfunction
trips and capacitor destruction.
Remove the power factor
correction capacitor and surge
absorber
Power factor correction
it
U
V
W
Inverter
IM
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.
Circuit interrupting when two or more inverters are used on the same power line.
MCCB1
MCCBn
MCCB3
MCCB2
INV1
INV2
INVn
(Circuit interrupting fuse)
Breaking of selected inverter
There is no fuse in the inverter's main circuit. Thus, as the diagram above shows, when more than one inverter is used
on the same power line, you must select interrupting characteristics so that only the MCCB2 will trip and the MCCB1
will not trip when a short occurs in the inverter (INV1). When you cannot select the proper characteristics install a
circuit interrupting fuse between the MCCB2 and the INV1.
If power supply distortion is not negligible
If the power supply distortion is not negligible because the inverter shares a power distribution line with other
systems causing distorted waveforms, such as systems with thyristers or large-capacity inverters, install an input
reactor to improve the input power factor, to reduce higher harmonics, or to suppress external surges.
■ Disposal
If an inverter is no longer usable, dispose of it as industrial waste.