Created Date: November 18,2009

Created by: milldrone

erwin p,

I will take a stab at this even though it's not a AD product. I only have experience with one altivar unit, 1hp I think. And some ancient SquareD units (mid 1980's)

good day,

We are facing problem regarding our crane hoist motor which controlled by ATV 71 AC drive. Motor is not running and only vibrates, though brake is open still it doesnt run and it draws 225A current

Ok! So you have confirmed the brake is released and that the drive is drawing 225A. Are you getting this reading from the drive display? Have you confirmed that the current is equal on all three legs of the motor? And all three legs of the supply? Have you disconnected the drive from the motor and then megged the motor? Be sure to disconnect the dive before the meggar test.

I dont know if it is in our drive problem or mechanical part because when we decoupled motor from gear box and tried to operate, motor starts to run and same thing happened after we fixed back the coupling, motor starts running normally.

Does this mean that you uncoupled the motor from the gearbox tried it again and it still vibrated? Then you refastened the coupling and it ran ok?

I'm presuming when you had the motor uncoupled, every thing rotated by hand ok, motor and gearbox?

Created Date: November 18,2009

Created by: erwin p.

Ok! So you have confirmed the brake is released and that the drive is drawing 225A. Are you getting this reading from the drive display? Have you confirmed that the current is equal on all three legs of the motor? And all three legs of the supply? Have you disconnected the drive from the motor and then megged the motor? Be sure to disconnect the dive before the meggar test.

Actually i got the 225 A reading on the drive display, and im not sure if current is present in all 3 legs of the supply. I also tried isolating the motor from drive but unfortunately an OUTPUT PHASE LOSS FAULT occur due to we activated the phase loss alarm on drive parameter. i havent tried also meggering the motor.

Does this mean that you uncoupled the motor from the gearbox tried it again and it still vibrated? Then you refastened the coupling and it ran ok?

I'm presuming when you had the motor uncoupled, every thing rotated by hand ok, motor and gearbox?

After i uncoupled the motor from gearbox and tried to operate the motor, motor runs smoothly.( I dont tried also to rotate both the motor and gearbox by hand.) So i doubted on gearbox that is why we again refastened the coupling and right after refastening the coupling we tried to operate again the motor and motor runs smoothly also...

Everytime this problem occurs we only uncoupled the motor from gearbox and after fastening the coupling to the motor problem was solved as if nothing happens.

Do you have any doubts about motor single phasing?

Created Date: November 18,2009

Created by: erwin p.

That is my doubt before but when I tried to uncouple motor from gearbox and operate the motor, motor runs smoothly, and right after i refastened the coupling and tried to operate motor vibration was gone and motor runs smoothly....

Do you have any other doubts so that i can check on my system...

Thanks.

Created Date: November 18,2009

Created by: milldrone

Do you have any other doubts so that i can check on my system...

Erwin,

Is there any means of disconnecting the motor from the drive? Like a service disconnect? Or is there a buss bar - traveling collector setup?

This might be a shot in the dark. From your amp reading (225A). My guess is this is either a 240, 480 or 575 volt system. Is your system a grounded Wye? A corner grounded delta? Or a floating delta? Is your crane the only thing serviced by the transformer secondary? Did you just recently fix a ground fault ?

Created Date: November 19,2009

Created by: erwin p.

Erwin,

Is there any means of disconnecting the motor from the drive? Like a service disconnect? Or is there a buss bar - traveling collector setup?

This might be a shot in the dark. From your amp reading (225A). My guess is this is either a 240, 480 or 575 volt system. Is your system a grounded Wye? A corner grounded delta? Or a floating delta? Is your crane the only thing serviced by the transformer secondary? Did you just recently fix a ground fault ?

I have a 400v grounded wye system. Actually recently we just fixed a ground fault not on crane but on the other circuits which was connected parallel to the feeder of this crane power supply. And when we measure crane power supply that time we get reading 380v on all phases with ground. do you think this is the cause of the problem? and is there any countermeasure?

thanks.

Created Date: November 19,2009

Created by: milldrone

I have a 400v grounded wye system. Actually recently we just fixed a ground fault not on crane but on the other circuits which was connected parallel to the feeder of this crane power supply. And when we measure crane power supply that time we get reading 380v on all phases with ground. do you think this is the cause of the problem? and is there any countermeasure?

thanks.

Was the ground fault in effect at the time the motor was misbehaving? Perhaps the drive has a protective feature to protect itself from a ground fault. and this is what caused the symptom.

I do not know if that was the problem or not. I have experienced a floating delta and a motor that had a internal ground fault with a ancient Square D drive have the same symptoms. I cannot say that that is your problem. The motor in my case ran fine across the line (with a ground fault of course). Everyone else though the drive was bad. I proved it was not by connecting to a good motor.

For test purposes next time this happens, do you have a motor near the VFD that you can swing the VFD output to?

Created Date: November 19,2009

Created by: erwin p.

Was the ground fault in effect at the time the motor was misbehaving? Perhaps the drive has a protective feature to protect itself from a ground fault. and this is what caused the symptom.

I do not know if that was the problem or not. I have experienced a floating delta and a motor that had a internal ground fault with a ancient Square D drive have the same symptoms. I cannot say that that is your problem. The motor in my case ran fine across the line (with a ground fault of course). Everyone else though the drive was bad. I proved it was not by connecting to a good motor.

For test purposes next time this happens, do you have a motor near the VFD that you can swing the VFD output to?

Actually ground fault doesnt affect the motor that time. Anyways thanks for your advice milldrone. That is what im looking forward also. the next time my hoist motor vibrates again i will shift the connection to other motors so that i can confirm if the problem is on the drive or on the motor. THANK YOU VERY MUCH......

Created Date: November 17,2009

Created by: erwin p.

good day,

We are facing problem regarding our crane hoist motor which controlled by ATV 71 AC drive. Motor is not running and only vibrates, though brake is open still it doesnt run and it draws 225A current causing for drive to tripped for motor overload fault. I dont know if it is in our drive problem or mechanical part because when we decoupled motor from gear box and tried to operate, motor starts to run and same thing happened after we fixed back the coupling, motor starts running normally. motor is not hot when it vibrates. also we dont use shaft encoder in our motor.

Any help that you will provide would be highly appreciated.

Thanks in advance.