Ground Fault Relay trip on 2300v starter

[BearB]

Any thoughts or direction on this would be appreciated.
The plant where I work we have had a GE 228X275 on a Ground Fault Relay in a 2300v Full Voltage Induction Motor Starter trip when the motor stop switch was pushed, routine way it is stop. This has happen twice, I did not see it I was told about it. The motor and leads were megger and were ok. The GE 228X275 Ground Fault Relay and CT are only about 1 1/2 years old in operation and this is the first trip.

 

[jraef]

What kind of motor starter? Vacuum or air-break?


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376

 

[BearB]

vacuum

 

[Laplacian]

What are the GF relay settings? Have you verified that all three contactor poles open together? One pole could be opening up ahead of the other two; enough ahead to allow pickup of the GF relay.

 

[jraef]

That's where I was going with that as well. The GF relay is likely using the Residual Current method and if one contact opens before the other two, the imbalance may trigger the GF relay pick-up. The vacuum bottle contacts may have worn and need adjustment. Some brands have an indicator on the side, check for that.

Also if you have ever had the vacuum contactor open under a fault, you may have vapor deposition on the inside of the vacuum bottle(s) which is allowing tracking for a little too long. That would require replacement of the bottles.


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376

 

[BearB]

The medium voltage vacuum contactor is a Cutler Hammer
Type SL N014S5W-550 and is about 1 1/2 old. Thanks for the feedback this site is a great help.

 

[Zogzog]

You should test this breaker, contact erosion inspection and vacuum integrity tests at least.