AQ: ACS800-104-0105-3 (ABB VFD Drives)
Question:
I have a problem with ABB ACS800-104-0105-3 drive model, the output current reading on the VFD is always double the reading of the clamp ampere(i.e. drive reading= 40 A, clamp ampere reading=20 A), what is the procedure that i can follow to detect the cause of this error?
Answer:
I don’t know about ABB drives, but hope this thing will help you.
1. The variable frequency drive may have problem with current sensor, just replace with another drive for comparison.
2. Make sure you use, true RMS type clamp meter.
3. If there is leakage current (through cable insulation and air) between each phase. This normally because of the cable insulation already degraded. Add output reactor and replace the cable with suitable insulation can fix this kind of problem.
4. If there is leakage current between this VFD drive and the other drives, that both motor cable is quiet long and run in parallel together.
To Collect more data and get more idea, you can do this:
1. Clamp all the 3 phase motor cable together using clamp. The reading will show you the leakage current. Normally about 10% of motor rated current at full load.
2. Check the current on each phase, and see if the current is balance for each phase.
3. Run the variable frequency drive without the motor cable, check the current reading and clamp meter.
4. Run the AC drive with the motor cable but without the motor, check again the reading and clamp meter.
5. Run the drive with motor, check if any oscillation in motor current.
6. Check current input to the AC drive inverter.
7. Turn of the other drive (if the motor cable run parallel together with other VFDs), and see if any change in current.
