Electric motor voltage
Electric motor voltage
(OP)
I received a call from a friend that his V'S is acting up and would like me to look at it. The VSD controls one 20 hp motor. The VSD is in fault mode showing over voltage. When I check the voltage it is correct with what is supposed to be present. "480/240 3 phase.
This system has 12 motors that are being fed from a plant generator.
I have isolated all 12 motors to check each one individually. When I energize on of the motors the phases go unbalanced, phase to ground readings L1/2.4 volts-L2/498 volts, L3/498 volt. I
I assume this high voltage feed back is what is causing the VSD to fault but is is the generator under load causing the problem or the one motor leaking due to bad windings or stater. Also the motor seems to be work fine with no visual problems.
This system has 12 motors that are being fed from a plant generator.
I have isolated all 12 motors to check each one individually. When I energize on of the motors the phases go unbalanced, phase to ground readings L1/2.4 volts-L2/498 volts, L3/498 volt. I
I assume this high voltage feed back is what is causing the VSD to fault but is is the generator under load causing the problem or the one motor leaking due to bad windings or stater. Also the motor seems to be work fine with no visual problems.





RE: Electric motor voltage
After you have done that call us back.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Electric motor voltage
If on the input, who cars?
Are you SURE it is THIS issue? Overvolts fault is not the one you would get if phase to ground fault on output, and phase to ground on input is a "I dont care."
Overvolts is from stopping too fast; ie., sending too much energy back to the drive stopping the motor. Solution to it is either slow down your decel or add more DB braking.
Something is not quite jiving yet....
www.KilroyWasHere<dot>com
RE: Electric motor voltage
Mike - "...phase to ground on input is a 'I dont care.' " is often not true because of filter components connected to the frame.
RE: Electric motor voltage
"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington
RE: Electric motor voltage
Thanks ScottyUK for your correction; I should have included phase to ground on input is a 'I dont care' when diagnosing an output overvolts fault. I have blown my share of input MOVs on grounded corner delta systems!
www.KilroyWasHere<dot>com