Toshiba VF-AS1 - Manual (Page 10)

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2.2. Precautions
1. Make sure to interlock the magnetic contactor (MC3) on the inverter output side with the
commercial power supply magnetic contactor (MC1).
2. Magnetic contactor (MC2) can be omitted for normal operation but this is needed to isolate the
inverter circuit in case a short-circuit fault occurs inside the inverter. Examine whether it should
be installed or not considering the importance of the system concerned.
3. Check to make sure the phase sequence of the inverter and that of the commercial power
supply are the same beforehand to maintain the motor’s rotational direction unchanged before
and after the power switching.
4. In the   (Reverse-run prohibition), do not use the forward direction disable setting
(  =2). Switching to commercial power supply cannot be made because the inverter
cannot run forward.
5. If the cause of the inverter trip was OCL (short-circuit on the load side at startup), E (emergency
stop) or EF1, 2 (ground fault), commercial power supply / inverter switching output 1, 2 (output
terminal selection 46, 48) are both shut off and MC1 and MC3 on both inverter and commercial
power supply sides disabled and unable to turn on.
6. When the setting value for  (output signal selection of commercial power supply/inverter
switching) is “2”, the system does not work even if the commercial power supply switching
signal is turned on at the time of an inverter trip.
To switch to commercial power supply, remove the cause of the protective action and reset the
inverter and then enter the switching signal to switch to commercial power supply.
7. S2 terminal (emergency stop) can be omitted, but it is needed as a circuit to detect a motor
overload when the motor is operated on commercial power supply. Examine whether it should
be installed or not considering the importance of the system concerned.