The inverter trips if the communication fault of the built-in CPU occurs.
Check for devices producing excess electrical noises around the inverter.
Take measures against noises if there are devices producing excess electrical noises around
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Operation panel power supply short circuit/RS-485 terminal power supply short circuit
When the power supply for the operation panel (PU connector) is shorted, the power output
is shutoff and the inverter trips. The use of the operation panel (parameter unit) and the RS-
485 communication via the PU connector are disabled. To reset, enter the RES signal from
the terminal, reset via communication through the RS-485 terminals, or switch power OFF
then ON again.
When the power supply for the RS-485 terminals are short circuited, this function shuts off
the power output. At this time, communication from the RS-485 terminals cannot be made.
To reset, use STOP/RESET key of the operation panel, enter the RES signal, or switch power
OFF then ON again.
Check that the PU connector cable is not shorted.
Check that the RS-485 terminals are connected correctly.
Check PU and cable.
Check the connection of the RS-485 terminals.
24 V DC power fault
When the 24 V DC power output from the PC terminal is shorted, this function shuts off the
At this time, all external contact inputs switch OFF. The inverter cannot be reset by entering the
RES signal. To reset it, use the operation panel, or switch power OFF, then ON again.
Check for a short circuit in the PC terminal output.
Check that the 24 V external power supply voltage is correct.
Repair the short-circuited portion.
Supply the power at 24 V. (If the power at insufficient voltage is supplied to the 24 V input
circuit for a long time, the inverter internal circuit may heat up. Input power at correct
voltage although it will not damage the inverter.)
Causes and corrective actions
24 VDC power fault
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