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Discussion Starter · #1 ·
Last thursday i get a call about one of our vacuum pumps is tripping out. When i get there i check to make sure my fuses are good(they were) Reset the heaters and pull amps on it. I get readings of 340-340-550 with the high legs tripping the heater about 6 secs into the motor coming on. I go out to the pump and check it everything there. pump is not locked as it turn freely and so does the motor. The motor smells cooked. Open the pecker head and i check my connections everything is still taped(i do a layer or two of black tape then 2 layers of rubber splice tape then a final two layers of black again).

Break my connections and meg the motor. It is megging out fine. Meg my wire from the bucket to the motor(still disconnected from the motor) and they are reading good. Put it all back together and leaving the pump off the motor fire it back up. Same readings agai n with the same leg tripping the heaters. Not the first time i have had a motor meg good but be bad so i let the super know about it. Motor sits over the weekend and it appears no one passed on the info the motor was bad because they come in put it all together yesterday morning and turn it on. and havn't had problem from it since.
It is enough to make me beat my head on the wall
 

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Bilge Rat
motors and controls.........
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9,505 Posts
Did you check voltage phase to phase.

It wouldn't take much imbalance to cause that much of a difference in current.

This may very well have been a POCO problem that they have fixed, and when they supplied better voltages, your problem disappeared.
 

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Discussion Starter · #3 ·
Voltage was 275-279 to ground and varied from 479-485 phase to phase.
This is what the plant normally runs with the weekends being alot higher do to there being almost no loads running in the plant
 
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