Phase Fault Problem in ACS800 Drive

My first inclination is a problem in the motor that the drive can detect, because of having better protection systems, but in bypass all you have is a simplistic overload relay so it does not see the problem. Yet.

But in reviewing the ACS800 manual that I have, I don't see a fault display that says "Phase Fault". Is there an asoociated code number on the display?

Please check the direction of measuring CT's, phase sequence and trip threshold settings of the relay/drive. With phase fault indication and the motor taking full load ( presumably for some time ) in bypass mode with OLR protection and hopefully HRC / MCCB also in series, I do not expect any major problem in the motor. I expect some problem in control or protection circuit wiring. Or also probably in the VFD drive itself.

Dear Friend, Is that use multiple Fuse in converter bank ? If yes then please check Fuses and All thyrestor indivisualy. I was facing same problem in ACS 800 with 560 KW motor for re-cerculation fan and motor was triped on 350 Amps where RPM was 500. We check and found one of the thyrestor was faulty and same phase fuse blowen. After replacing the thyrestor and fuse the motor run on 100% RPM on load.

Regards

It is probably a drive problem not a motor problem. An modern AC drive is very carefully monitored internally and almost any unbalance even instantaneously can be seen by the drive as a phase fault and cause shutdown. The worst I ever found was a drive in a steel mill that would run perfectly if the door were open but would shut down quickly any time the door was shut. It turned out that a wire in one of the harnesses had a break internal to the wire and the ventilating fans in the drive put pressure on the harness with the door shut and not when the door was open. The only way we found it was lots of digital tracking monitors moved around until we found a signal that changed and then tracked that down. At least your problem sounds consistent so with monitors it can be tracked down. This size drive usually has some internal tracking capability and that should be exercised to find out as much as possible about the problem, but you may have to start monitoring individual points within the drive. If you do not feel comfortable be sure to contact the field service from the manufacturer. This manufacturer was a competitor to my company, but at my last location their field office was in the opposite end of the same building ours was and they were competent field engineers. The other thing is that you said you were installing it. Is it a new unit? If it is it is still under warranty. Certainly call them immediately if it is. I may not like their products, but I have never heard of them not standing behind them. It was always frustrating to have a customer that bad-mouthed a product with a small correctable problem but had never called, even when the product was in warranty. I have not heard of any inherent problems with this particular drive, but it is a complicated unit and a phase fault can be caused by nearly anything on an AC drive.

I M VERY SORRY FOR THE MISTAKE That,It is ABB ACS 850 not ACS 800. ABB Service Engg. is also with us.we also replace all the thyristors and SFU also,still having problem fault code is 15 .in fault logger it is showing 3006 SUPPLY PHASE FAULT.

Might want to check and see if the motor and VFD are wired correctly.Many FVDs are not very happy when the phases are swapped on the inputs, and outputs.

Make sure L1 is hooked to L1, L2 to L2, L3 to L3, and if used Neutral to Neutral. Likewise T1 to T1 etc on the outputs.

Another possibility is a faulty winding insulation in the motor which allows current to flow once the voltage/current reach a certain point. Meg the motor to check for that.

Horizon,

It does look like an insulation breakdown once a high voltage / freq is attained.

If the megger doesn't find the problem, I would try to swap the two motors if the two drives are side by side to see if the problem is in the drive or in the motor and its wiring.

Adding a snubber on the motor side may reduce the dv/dt sufficiently to eliminate the problem or at least to verify that it is an insulation breakdown caused by the IGBT switching.

The motor attains full speed and takes the full load in parallel star delta circuit. Hence incipient insulation failure can be ruled out.

I have seen quite a few motor windings insulation fail under the high frequencies generated by VFDs, that pass muster just fine when operated under conventional frequencies eg. 60Hz/50Hz. Modern VFDs can generate switching frequencies well into the low frequency radio bands, 10KHz to 60KHz, at these frequencies even a minor insulation flaw can pass current and cause a phase trip, due to induced harmonics into the adjacent phase windings.

I always suggest using shielded cable for VFD installation, for just this reason. Specially if the VFDs are located close to each other in an MCC and/or share common wire ducts/trays.

Thank you for the input. Just wanted to know what is the trigger for phase fault alarm in the unit. Is it voltage based or current based. I do not have the ABB reference manual. Some earlier replies indicated that phase fault alarm is linked to voltage issues rather than current issues. If yes and considering the fact that the motor has run at full load and speed in the parallel circuit, it was my opinion that it is not linked to any insulation failure.

I request the OP to revert with whether the problem has been identified and solved.

"Just wanted to know what is the trigger for phase fault alarm in the unit. Is it voltage based or current based. I do not have the ABB reference manual. Some earlier replies indicated that phase fault alarm is linked to voltage issues rather than current issues. If yes and considering the fact that the motor has run at full load and speed in the parallel circuit, it was my opinion that it is not linked to any insulation failure."

The phase fault logic looks at the balance of voltages and currents between phases. If one phase is responding differently than any other based on what the drive is attempting to do you get a phase fault. It really doesn't matter if ABB looks at voltage or current, it is the difference between phases that shows up as a phase fault. This can be caused by breakdown in insulation within windings, damage to core steel, or an intermittent open in a motor winding but in a modern drive it is usually a drive problem and one of the problems is around the semi conductor elements themselves. In your case I would expect it to be in drive since you have no problems running on bypass. I have seen motor problems that can make it through bypass mode but it is very rare. You need to get an expert on the drive to look at it. With the questions you ask, you will have a tough time diagnosing the problem, much less implementing the repair. I suggest you call ABB field service or if that is not available GE field service is also capable. If you have a really good local service you trust you can try that but most independent groups cannot handle this type of problem. It is my opinion that this is an internal drive problem and will need wave shape recorders at the correct places internal in the drive installed to find it. The repair will probably be inexpensive but the diagnosing will be $$$.

the stated problem finally solved..... after inter changing all equipments one by one (from FD 2 to FD 1 Drive) finally FD 1 runs with 1480 rpm,520A. It only happens after changing the IGBT Section of faulty drive.