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What does OCA mean on the ATV21 and ATV212 drives?

FA174648

19 October 2021

Issue:
OCA fault on ATV21/ATV212 drives?

Product line:
Altivar 212, ATV212, S-Flex

Environment:
All models, all serial numbers.

Cause:
Overcurrent during start-up or ground fault

Resolution:
OCA – short-circuit detected in drive output inverter stage during motor startup

Check that Line and Load cables are connected to the proper terminals.  Line cables go to R/L1, S/L2 and T/L3.  Load or motor cables go to U/T1, V/T2 and W/T3. 

Disconnect the motor leads from the drive.  Using a 1000V Megger, check the motor and motor leads for shorts or ground fault.

Try a voltage balance test.  With the motor leads still disconnected, set parameter F605 to 0 (disable Output Phase Failure).  Run the drive at 20Hz, 40Hz and 60Hz.  At each speed measure the line to line output voltages to see if they are balanced.
Don't forget to reset F605 to it's previous value after testing has been completed.

If line output voltages are measured balance at 20Hz, 40Hz, 60Hz.  Then, motor is needed to check with a 1000V Megger to see if the motor is bad.