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phase converter problems?

Posted By: watthead

phase converter problems? - 09/14/11 12:32 AM

I need an expert or someone with a working knowledge of phase generators. I have phase convertor that runs a small piece of equipment with 3 three phase motors. The problem is a 5hp fan motor is going out on overload. I believe the problem is in the convertor but I am not sure. The single phase 240v supply to the convertor is good. The no load voltages at the convertor are A=122v B=122V C=196v AB=244v BC=210v AC=206v. The currents at the 5hp fan motor are A=2.9 B=20.2 C=13.1 under this load the voltages are AB=240 BC=196 AC=206 Anyone have any ideas or suggestions to determine the actual problem. They would be more than welcomed
Posted By: JoeTestingEngr

Re: phase converter problems? - 09/14/11 03:46 AM

You should probably supply info on the type of converter that you are using.
Posted By: watthead

Re: phase converter problems? - 09/14/11 04:38 AM

it is a rotary converter that has been in service for a couple of years.
Posted By: LarryC

Re: phase converter problems? - 09/14/11 05:21 AM

When you open up the converter, it has a bunch of canned power capacitors, correct? If so, my GUESS is that you have some bad capacitors. Look for the ones that are swelled or really hot.

Did you have some recent power outages or local lightning strikes? Those caps are AC rated electrolytics. Make sure if they need to be replaced, that you pay attention to the voltage ratings. If I remember right, they were typically rated for 600 VAC.
Posted By: watthead

Re: phase converter problems? - 09/14/11 05:53 AM

Yes there are capacitors inside the starter enclosure. I will check those , thanks.
Posted By: watthead

Re: phase converter problems? - 09/14/11 11:32 PM

Thanks Larry, it was the capacitors. Both run capacitors were bad and when replaced the B phase current fell drastically.
Posted By: Tesla

Re: phase converter problems? - 09/15/11 03:50 AM

Not withstanding their higher price -- you're better off with Run Caps...

They're made to MUCH higher standards.
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