ACS800 Current Unbalance
I have an ACS800 multidrive setup with ACS800-104LC-0705-7 drives. I have been told by my technicians at the wind farm that I have a current imbalance fault on one of them.
I have made a test rig with two of them in parallel and want to find which one has the current imbalance. I'm the lead tech here and background in electronic engineering I'm hoping to solve the issue myself...
I have been told that the issue is most likely the gating boards inside the drive (and thus to buy an IGBT kit) I found this info in the Input Supply Module Training pdf. I've also been directed to use the APBUDL program to download the data from the inverters and I have communication and received data. The problem is that in my shop I don't have the load that they have in the turbine thus my load is only 3% of the total current so I get low readings on my datalogger. I want to scale that current reading so I can see the current imbalance.
I have access to the AS7R7365 standard firmware and believe I should be able to change a parameter (max current?!) and then upload the firmware. Ive done this many times before on other test rigs I've made. Any ideas on what parameter I need to change? I've tried lowering parameter 190.2 thinking that my load will be a higher percentage of a lower max current. I can see the data saves fine to the RDCU but my current never increases (same load) - it only ever decreases!!!
One last question:
As my issue is current imbalance that i'm trying to solve I even disconnected an output phase from one of the parallel inverters and the drive didn't trip! I was thinking this should have tripped as it would then be unbalanced (all current going through the other inverter's module) however this wasn't the case! How can I simulate a current imbalance?
Thanks SO much! I hope to get this sorted ASAP so I can get some spare inverters for our farm.
What I found in FW manual:
CUR UNBAL xx (2330)
Drive has detected excessive output current unbalance in inverter unit of several parallel connected inverter modules. This can be caused by external fault (earth fault, motor, motor cabling, etc.) or internal fault (damaged inverter component). xx (2...12) refers to inverter module numberSo, check Fault message and from xx number you could see the location of the inverter module, which reports the fault.
Unfortunately, I don't know how to simulate it, if you don't have a real load. Parameters 190.x are hidden parameters, so I don't recommend you to modify them without to know what they mean. Usually service persons can do that (in some cases). You can damage the drive, putting wrong data there.
My advise is - chack output circuits of the drive.
In case you think the problem is inside the drive, it is better to contact you service organization.