ABB ACS550 + Washguard Leeson motor problem

Hello,

I have Leeson c213T17WC3a (G140467.00) motor installed with ABB ACS550 - they are used for a pool jet stream.

This jet stream stopped working and I noticed that control panel says that motor is draining 24 amps (maximum allowed by control panel) and is delivering only 40 RPM.

My ideas are:
1) water flow may be restricted by something inside the pipe (maybe chemicals or garbage?)
2) motor had failed
3) ACS550 had failed
4) due to the recent electricity interruptions ACS550 settings were lost and it is not properly configured, so can't start the motor properly

Could you please advise what could be the problem? I do not know where to start troubleshooting...

What is the error message on your vfd.

All of VFD (inverters) has its maintenance and trouble shooting aid.

It will tell you the reason why it is stopping, Wheter over voltage, Under voltage, over load etc.

When the motor quits working, before resetting the vfd, check first what error message it is giving so you will be able to figure out what is happening and you will be able to correct the issue.

I would first start by powering down the panel, wait for the VFD DC Bus to bleed off to a safe (near zero) voltage, disconnect the motor and "ohm it out".

Make sure your motor circuit is not broken somewhere between the drive and the motor, by ohm testing the whole circuit phase to phase. All reading from phase to phase with an ohmmeter should match and be pretty low Ohm values (depending on horsepower, and assuming a normal 3 phase induction motor). Also check phase to ground and you should read a very high or OL reading.

While it is off and in a safe state, if possible check for mechanical binding. Is there trash in the pump? broken coupling? Can you spin the motor shaft freely?

I have seen other brand drives stall out during acceleration when the motor has an increase in load, when there is an open circuit or turn to turn short on one phase, but normally, the VFD will detect any major fault in the motor. It is the smaller motor faults that the VFD may not detect.

I don't have first hand experience with that particular drive to tell you what fault codes or parameters to check, but it sounds like the VFD is trying to run the motor and not faulting. If the 24 amps is above the motor FLA, and the VFD is programmed correctly, the drive should fault, given enough time.

infr said:

Hello,

I have Leeson c213T17WC3a (G140467.00) motor installed with ABB ACS550 - they are used for a pool jet stream.

This jet stream stopped working and I noticed that control panel says that motor is draining 24 amps (maximum allowed by control panel) and is delivering only 40 RPM.

My ideas are:
1) water flow may be restricted by something inside the pipe (maybe chemicals or garbage?)

Click to expand...

Unlikely. It is probably a centrifugal pump, so no flow = no load.

It might more likely be a BROKEN pipe and you have what's called "open channel" flow (no restriction), which might make the drive go into current limit mode, which causes it to reduce the speed in order to reduce the load on the drive.

2) motor had failed

Click to expand...

Also unlikely, because the VFD would detect it and trip, not run at the wrong speed. Unless the motor is not grounded properly, which would be a VERY bad thing for anything having to to with a pool!

If so, you might have current flowing to ground that the VFD is NOT detecting (because it has no ground reference). This would be a VERY VERY dangerous situation!!!

3) ACS550 had failed

Click to expand...

Again, unlikely unless the VFD is showing a fault of some sort, in which case it's unlikely that it would be running the motor at all.

4) due to the recent electricity interruptions ACS550 settings were lost and it is not properly configured, so can't start the motor properly

Click to expand...

Much more possible. Under the right (wrong) circumstances if the memory of the VFD was damaged or corrupted during power fluctuations, it may no longer have the right programming and is running on some sort of factory default values.

Not listed:
5) Your pump has a bad bearing or some other mechanical problem which is increasing the load on the motor, causing the current limit / speed reduction response from the VFD as mentioned above.

6) You have lost a phase on the incoming supply, which artificially limits the VFD's capacity, so it is again, lowering the load by reducing the speed to reduce the strain on the power components of the VFD.

Sounds to me like the motor rotor is locked and the drive current limit is holding it at 24amps and 40hz without faulting. Eventually it should fault on motor overtemp but I can't tell if the programming is done properly to make this happen.

Check out motor/pump mechanical situation first.

Many thanks to everyone who shared thoughts on this!

jparale said:

What is the error message on your vfd.

Click to expand...

The problem is - there is no error message, VFD is running the motor on very low RPM at maxed out AMPs:


(image does not want to load, here is the link to it: http://postimg.org/image/syqyt6hgb/)

OkiePC said:

I would first start by powering down the panel, wait for the VFD DC Bus to bleed off to a safe (near zero) voltage, disconnect the motor and "ohm it out".

Click to expand...

Thank you, I will "ohm out" the motor during this upcoming weekend and will share the results here.

OkiePC said:

...it sounds like the VFD is trying to run the motor and not faulting. If the 24 amps is above the motor FLA, and the VFD is programmed correctly, the drive should fault, given enough time.

Click to expand...

Yes, VFD is not faulting, but I did not give it enough time. I think the longest I have ran it (since the issue appeared) was for 2, maybe 3 minutes. However, 24 amps is within the motor FLA (click to see the FLA), so I guess running it for longer will not cause VFD to fault, but I can try to do this if needed.

Unfortunately it is not easy to check if motor/pump is clogged, but if control panel says it is rotating at 40 RPM, I tend to think this rules out the clogged motor.
If this assumption is wrong, I think I could take the motor off and check if it can rotate freely.

jraef said:

Unlikely. It is probably a centrifugal pump, so no flow = no load.

Unlikely. It is probably a centrifugal pump, so no flow = no load.

It might more likely be a BROKEN pipe and you have what's called "open channel" flow (no restriction), which might make the drive go into current limit mode, which causes it to reduce the speed in order to reduce the load on the drive.

Click to expand...

Interesting, so if I will disconnect the motor from the pump and will try to rotate it without load, should I expect it to rotate at maxed out amps and low RPM (due to no load)? This sounds strange, I would rather expect motor to rotate fast at low amps.

jraef said:

If so, you might have current flowing to ground that the VFD is NOT detecting (because it has no ground reference). This would be a VERY VERY dangerous situation!!!

Click to expand...

I will check the grounding. Is there any way I could check if current if flowing to ground (apart from touching it )

jraef said:

Under the right (wrong) circumstances if the memory of the VFD was damaged or corrupted during power fluctuations, it may no longer have the right programming and is running on some sort of factory default values.

Click to expand...

If I wanted to check the programming, where should I start? VFD manual?
I have no experience with VFDs, but I would say I am tech savvy.

jraef said:

5) Your pump has a bad bearing or some other mechanical problem which is increasing the load on the motor, causing the current limit / speed reduction response from the VFD as mentioned above.

Click to expand...

This motor was installed only couple of years ago and was used lightly, besides, there is no loud noise when it is running at 40 RPM... so probably failed bearing is not the case.

jraef said:

5) 6) You have lost a phase on the incoming supply, which artificially limits the VFD's capacity, so it is again, lowering the load by reducing the speed to reduce the strain on the power components of the VFD..

Click to expand...

Thanks, I will check that, but I would think VFD control panel would be able to recognize this fault.

Don't try to ohm it with it connected to the VFD. If you have access to a megohmmeter to test the insulation, that is always a good idea. Never apply your ohm meter or megohmeter to the VFD terminals.

If it is stalling at 40rpm and 24 amps and that is below the FLA, it will not fault (there are exceptions).

Could it be a speed reference gone wrong?

The VFD should provide a way to run the motor from a keypad speed command. This could rule out any external speed reference that may be failed.

The VFD is probably configured in V/Hz mode. In that mode, the display can easily show 40 rpm when, in fact, the motor is not turning.

I'm confident you will find the motor and pump is locked up.

OkiePC said:

Don't try to ohm it with it connected to the VFD. If you have access to a megohmmeter to test the insulation, that is always a good idea. Never apply your ohm meter or megohmeter to the VFD terminals.

Click to expand...

Understood. I was going to disconnect the motor and "ohm" the cables connected to the motor only.

OkiePC said:

Could it be a speed reference gone wrong?

Click to expand...

It is definitely not rotating at its normal RPM, because there is no jet in the pool (no water movement).

DickDV said:

The VFD is probably configured in V/Hz mode. In that mode, the display can easily show 40 rpm when, in fact, the motor is not turning.

I'm confident you will find the motor and pump is locked up.

Click to expand...

This is interesting. I could not visually confirm that rotor is spinning. I thought I just could not see any moving parts of the motor. I will look again into it. If it is possible that control panel will show 40 RPM when motor is not actually rotating, then I ruled out locked-up pump too soon.

LOTO

decoupling the motor shaft

test

Well, I feel myself like a complete idiot now.

I looked at the whole assembly and was able to find access to motor shaft. I tried rotating it, but it seemed stuck. I applied hand torque clockwise, then counterclockwise and repeated this several times until the shaft became free.

I started the motor and it works fine. I tend to think that it is louder now, so will read LEESON manual and see if I will need to grease the bearings, but this will be a different story.

Many thanks to everyone helping out with this issue!!