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Table 1.8 Fault Display and Contents
Digital Operator
fault display
Contents Possible
Cause/
Corrective Actions
OC
(Over-current)
Inverter output current exceeds 200% of
rated current.
(Momentary action)
The following cause can be considered:
inverter output side short-circuits. Excessive
short setting of accel/decel time, [constant
Pn-09~12] special motor use, motor start
during coasting, start of motor with larger
capacity than inverter, inverter output side
magnetic contactor ON/OFF.
Reset after finding the cause.
OV
(Over-voltage)
Main circuit DC voltage exceeds 410 V or
more for 2220 V class. 820 V or more for
440 V class because of excessive
regenerative energy from motor. (Exceeds
over voltage protection level.)
Decel. time setting is not sufficient.
[Constant Pn-10, 12] or minus load (cranes,
etc.) is decreasing. Increase decel. time or
connect a braking resistor (option).
UV
(Under-voltage)
Under voltage status is entered. [Main
control DC voltage becomes approx. 210
V or less (220 V class 3-phase).170 V or
less (220 V class single-phase) or 420 V or
less (440 V class 3-phase)].
Input power supply voltage is reduced,
phases are opened or momentary power loss
occurs, etc. Check the power supply voltage,
or check that main circuit power supply
wiring is connected properly or terminal
screws are tightened well.
OH
(Cooling Fin
Overheat)
Temperature rise caused by inverter
overload operation, or intake air
temperature rise.
Cooling fan r/min is decreased
Load is too large, V/f characteristic are not
proper, setting time is too short or intake air
temperature exceeds 113°F (45°C), etc.
Correct load size, V/f set value [constant
Pn-02~Pn-08] or intake air temperature.
Check the cooling fan.
