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Old 12-17-2017, 09:41 AM
threepiece threepiece is offline
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Default Running Motors Using a Phase Converter?

I find that motors that I start on my phase converter don't always start on the first contact. I have a 20 HP rotary converter connected to my 7.5 HP lathe, it sometimes growls at me when I try to start it, sometimes two or three times in a row before it cooperates with my intention. I recently bought a 5 and a 10 HP motors from the scrap yard, the 10 HP motor was very uncooperative, but I did manage to get it spinning normally after several attempts. It usually jerks a bit like it wants to turn but then growls back at me.

Can someone shed some light on this matter? Thanks for any input.
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Old 12-17-2017, 11:07 AM
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Walker Walker is offline
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Sounds like there is something wrong with your phase converter.
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Old 12-17-2017, 11:38 AM
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terry lingle terry lingle is offline
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Without a schematic of your system
i am assuming that you have a rotary converter and that you start the converter first. look at all contacts in the power path then check the contacts on the magnetic that closes to start the lathe.

If it is a static converter without a dedicated idler meaning that it uses the lathe motor as the rotating part of the converter again check for burner contacts in the high current paths. If nothing seems bad there look at the connectors in the capacitor bank look for melted insulation and signs of arcing.

If nothing shows up post a schmatic of the complete set up including the converter and the lathe electrics then we can suggest specific step by step troubleshooting procedures
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Old 12-17-2017, 12:58 PM
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Try testing the three legs for proper voltage.
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Old 12-17-2017, 02:17 PM
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Shade Tree Welder Shade Tree Welder is online now
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Test your voltage as mentioned, phase to phase as well as phase to ground.

But sounds like a open, loose or burn connection to me. Also could be a
bad capacitor.

But my bet is on the converter and not on you equipment.

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Old 12-19-2017, 03:37 PM
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Where is the contactor for the motors getting it's coil voltage ?
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