Bad Start or Run Capacitor 1

[Splitrings]

We are still having trouble with a single phase 230v 60hz 10hp motor. It occasionally trips the thermal reset. I posted last year the following thread: thread237-317705
Yesterday we ran the motor for the first time since last year. It is used in a maple sugar operation. The motor operates a liquid ring vacuum pump. What I noticed yesterday is that we the motor first starts there is an unbalanced current between both legs of about 12%. One was about 33 amps, while the other was 29 amps or so. After running for 20 minutes or so the difference was only a 0.1 amp or so. Is this an indication of a bad start capacitor?

 

[rasevskii]

Sounds like a moisture problem in the windings. If the motor is not used for long periods of time (months) and is in an unheated space, or there is a lot of humidity around, then such a problem may occur. As the motor warms up, the moisture will be driven off, but a ground fault may occur inside during the warmup time. Consider putting a small heater or heatlamp under the motor during the not in use period of the year.

rasevskii

 

[Splitrings]

That certainly could be possible. The motor is used outdoors in a semi enclosed space. The motor is a drip proof motor. Would a total enclosed motor be less susceptible to this?

 

[rasevskii]

Yes, a TEFC motor would be the better choice. But still a small heater would be desirable.

rasevskii