Delta VFD450C43S-00 - Page 910

Chapter 14 Fault Codes and DescriptionsC2000 Plus
14-7
ID* Display on LCD Keypad Fault Name Fault Descriptions
3
Over-current during
steady operation
(ocn)
Output current exceeds 2.4 times of the
rated current
during constant speed.
When ocn occurs, the drive closes the gate of the output
immediately, the motor run
s freely, and the display
shows an ocn fault.
Action and Reset
Action condition 240% of rated current
Action time Act immediately
Fault treatment parameter N/A
Reset method Manual reset
Reset condition Reset in 5 sec. after the fault is cleared
Record Yes
Cause Corrective Actions
Short-circuit at motor output due to
poor insulation wiring
Check
the motor cable and remove causes of the short circuits, or replace the
cable before turning on the power.
Check for possible shaft lock,
burnout or aging insulation of the
motor
Troubleshoot the motor shaft lock.
Check the motor insulation value with megger. Replace th
e motor if the insulation
is poor.
Impulsive change of the load Reduce the load or increase the capacity of AC motor drive.
Use special motor or motor with
larger capacity than the drive
Check motor capacity (the rated current on the motor’s nameplate should ≤
the
rated current of the drive)
Use ON/OFF controller of an
electromagnetic contactor at the
output (U/V/W) of the drive
Check the action timing of the contactor and make sure it is not turned ON /
OFF
when the drive outputs the voltage.
V/F curve setting fault
Adjust
V/F curve settings and frequency/voltage. When the fault occurs, and the
frequency voltage is too high, reduce the voltage.
Over-torque offset value too high
Adjust over-torque offset value (Refer to Pr.07-26
torque compensation gain),
until the output current is reduced and not motor stall.
Torque compensation is too large.
Adjust the torque compensation (refer to Pr.07-26
torque compensation gain)
until the output current reduces and the motor does not stall.
Malfunction caused by
interference
Verify the wiring of the control circuit and wiring/grounding of the main circuit
to
prevent interference.
The length of motor cable is too
long
Increase the AC motor drive’s capacity.
Install AC reactor(s) on the output side (U/V/W).
Hardware failure
The ocn occurs due to short circuit or ground fault at the output side of the drive.
Check for possible short circuit between terminals with the electric meter:
B1 corresponds to U, V, W; DC- corresponds to U, V, W;
corresponds to U,
V, W.
If short circuits occur, return to the factory for repair.