Compressor motor question

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  #1  
Old 08-31-12, 09:30 AM
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Compressor motor question

I bought a used Coleman 5HP 30 gal compressor. It has a single phase 120/240 motor. It is currently wired for 120. The motor runs hot but I understand this is common for a compressor motor. 160F measured on outside casing. I calculated 15 amps startup and it ocassionally trips a 20 amp breaker on 120. It pumps up to 130 psig and cuts back on when she drops to 100.

I thought if I wired it for 240 and 1/2 the amperage it would run cooler. I followed the diagram on the motor. End result it does nothing. I have power at the terminals on the motor itself so its ready to go. No noise, no smoke, no nothing.

My questions are...is there a way to check the motor to see if the windings are shot? would it run OK on 120 and possibly not 240? is 160 skin temp to high? Thanks for any thoughts.
 
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Old 08-31-12, 09:40 AM
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Welcome to the forums!

I thought if I wired it for 240 and 1/2 the amperage it would run cooler. I followed the diagram on the motor. End result it does nothing. I have power at the terminals on the motor itself so its ready to go.
How are you connecting the compressor to 240V single-phase power? How did you check the power on the motor terminals?
 
  #3  
Old 09-01-12, 05:43 AM
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Connecting with 2 wirs plus ground cable. I checked voltage at motor terminals. Both at 120 volts.
 
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Old 09-01-12, 05:53 AM
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Inside the peckerhead you should see a removable jumper (on some models) that must be switched in order to convert from 120 to 240. Can you post a picture of the wiring so we can see what you see? Your cut in and cut out is way too high. I should think about 85 on and 120 off. The motor and compressor are working against an almost maxed out pressure at 100 when it turns on presently.
 
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Old 09-01-12, 08:20 AM
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I thought if I wired it for 240 and 1/2 the amperage it would run cooler.
Doubtful. The heat generated is from the pump, not the motor. Any heat from the motor is normal.
It will run better on 240 then 120. You missed something on the conversion. Follow the others advice or post a picture of the diagram.
 
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