6.3 If an Alarm Code Appears on the LED Monitor
6-21
[ 29 ] 0Cn Instantaneous overcurrent
Phenomenon: The inverter momentary output current exceeded the overcurrent level.
0C1 Overcurrent occurred during acceleration.
0C2 Overcurrent occurred during deceleration.
0C3 Overcurrent occurred immediately after starting operation, or during running at constant speed.
(1) The inverter output lines were
short-circuited.
Disconnect the wiring from the inverter output terminals (U, V and W)
and measure the interphase resistance of the motor wiring. Check if the
resistance is too low.
➔ Remove the short-circuited part (including replacement of the wires,
relay terminals and motor).
If overcurrent is displayed when the inverter is run with the wiring
disconnected from the inverter output terminals (U, V, and W).
➔ The inverter may be faulty. Contact your Fuji Electric representative.
(2) Ground faults have occurred at
the inverter output lines.
Disconnect the wiring from the output terminals (U, V, and W) and
perform a Megger test.
➔ Remove the grounded parts (including replacement of the wires,
relay terminals and motor).
If overcurrent is displayed when the inverter is run with the wiring
disconnected from the inverter output terminals (U, V, and W).
➔ The inverter may be faulty. Contact your Fuji Electric representative.
Measure the motor current with a measuring device to trace the current
trend. Then, use this data to judge if the trend is over the calculated load
value for your system design.
➔ If the load is too heavy, reduce it or increase the inverter capacity.
Trace the current trend and check if there are any sudden changes in
the current.
➔ If there are any sudden changes, make the load fluctuation smaller
or increase the inverter capacity.
➔ Enable instantaneous overcurrent limiting (H12 = 1).
(4) Excessive torque boost
specified. The manual torque
boost is set if F37* = 0, 1, 3, or
4.
Check whether decreasing the torque boost (F09*) decreases the output
current but does not stall the motor.
➔ If no stall occurs, decrease the torque boost (F09*).
(5) The specified acceleration/
deceleration time was too short.
Check that the motor generates enough torque required during
acceleration/deceleration. That torque is calculated from the moment of
inertia of the load and the acceleration/deceleration times.
➔ Increase the acceleration/deceleration times (F07, F08, E10
through E15, and H56).
➔ Enable the current limiter (F43) and torque limiter (F40, F41, E16,
and E17).
➔ Increase the inverter capacity.
(6) Built-in braking transistor short
circuit detection activates:
(FRN0003G2S-2G to
FRN0288G2S-2G)
(FRN0002G2■-4G to
FRN0180G2■-4G)
Check whether the braking resistor connection terminals (P+, DB) have
shorted.
Check whether the resistance of the connected braking resistance is
excessively low.
➔ Connect an appropriate braking resistor.
(7) Malfunction caused by noise.
Check if appropriate noise control measures have been implemented
(e.g., correct grounding and routing of control and main circuit wires).
➔ Take noise countermeasures. For details, refer to Appendix A.
➔ Enable the retry function (H04).
➔ Connect a surge absorber to magnetic contactor's coils or other
solenoids (if any) causing noise.
The explanations for function codes with an asterisk (*) are limited to motor 1. If using motor 2 to 4, replace
with the relevant function codes in Chapter 5 "Table 5.3-21 Function codes to be switched".
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