ocA Over-current during acceleration fault in Delta C2000 plus drive
Cause: Output current exceeds three times of the rated current during acceleration.
– When ocA occurs, the drive closes the gate of the output immediately, the motor runs freely, and the display shows an ocA error.
Cause & Solution:
1. Acceleration time is too short
– Increase the acceleration time
– Increase the acceleration time of S-curve
– Set auto-acceleration and auto-deceleration parameter (Pr.01-44)
– Set over-current stall prevention function (Pr.06-03)
– Replace the drive with a larger capacity model.
2. 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.
3. Check for possible burnout or aging insulation of the motor
– Check the motor insulation value with megger. Replace the motor if the insulation is poor.
4. The load is too large.
– Check if the output current during the whole working process exceeds the AC motor drive’s rated current. If yes, replace the AC motor drive with a larger capacity model.
5. Impulsive change of the load
– Reduce the load or increase the capacity of AC motor drive.
6. Use special motor or motor with larger capacity than the drive
– Check the motor capacity (the rated current on the motor’s nameplate should ≤ the rated current of the drive)
7. 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.
8. V/F curve setting error
– Adjust the V/F curve setting and frequency/voltage. When the fault occurs, and the frequency voltage is too high, reduce the voltage.
9. 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.
10. Malfunction caused by interference
– Verify the wiring of the control circuit and the wiring/grounding of the main circuit to prevent interference.
11. The motor starts when in free run Enable the speed tracking during start-up of Pr.07-12. Improper parameter settings for the speed tracking function (including restart after momentary power loss and restart after fault)
Correct the parameter settings for speed tracking.
– 1. Start the speed tracking function.
– 2. Adjust the maximum current for Pr.07-09 speed tracking.
12. Incorrect combination of control mode and used motor
– Check the settings for Pr.00-11 control mode:
– 1. For IM, Pr.00-11=0, 1, 2, 3, 5
– 2. For PM, Pr.00-11=4, 6, or 7
13 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).
14 Hardware failure
– The ocA occurs due to the short circuit or ground fault at the output side of the drive.
– Check for possible short circuits between terminals with the electric meter: B1 corresponds to U, V and W; DC- corresponds to U, V and W; corresponds to U, V and W.
– If short circuit occurs, return to the factory for repair.
15. Check if the setting for stall prevention is correct
– Set the stall prevention to the proper value.