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    compressor (9 Posts)

  • Paul S Paul S @ 12:40 PM
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    I've heard of a way to use a megohmeter check compressor windings. I want to provide a good customer of mine some peace of mind from compressor breakdown before it actually happens Thanks Paul S
  • Techman Techman @ 6:15 PM
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    Hi Paul, single or 3 phase? Type? AC? Oil eye in crankcase? You have to keep records to compare from day/day ,week/week ,month/month  or yearly. Record the ambient temp also.Hand crank power or electronic meter?
    This post was edited by an admin on March 19, 2014 6:21 PM.
  • Paul S Paul S @ 8:59 PM
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    This is a deli with a few r22 split ac systems, single phase. but the systems that the customer is most concerned about is the medium temp walk in box (r22) and the freezer (r404a) both 3 phase....the walk in box i replaced the compressor (burnout \case grounded) about 8 years ago and all seems fine...i just diagnosed the freezers compressor case grounded....the new compressor has a oil eye in the crankcase...the meter is electronic from fieldpiece. thanks Paul S
  • RJ RJ @ 6:59 PM
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    megohm meter

    Supco M501 is a good inexpensive meter for checking hermetic compressors. about $160.00        New hermetic compressors will usually show a insulation resistance value of 100 megs or higher, readings of 50 megs or less indicate either the winding insulation is deteriorating or the oil/refrig is contaminated, may be moisture in system. The first step if you get a low reading would be to clean up system (install oversize liquid drier ). If you still get a low reading I usually explain to the customer that the winding insulation is breaking down and that premature failure of compressor is inevitable.  I have seen compressors run along time with low readings.  This meter can also be used to check motors and transformers. If you are going to work on larger equip. a crank style meter will give you more options     AmpProbe makes a good one    they can run in the thousands
  • Harvey Ramer Harvey Ramer @ 8:57 PM
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    Winding Measurements.

    Unless the manufacturer has prerecorded test measurements to use as a baseline, you have to do exactly what Techman said. It's not a once and done measurement. It's more of a monitoring and data collection process. Same goes for all motors. Every manufacturer uses their own insulating process dependent on the duties the motor will perform. The Chinese add gelatin to rainwater and use that for insulation.

  • unclejohn unclejohn @ 10:17 PM
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    If your talkin

    Tin cans your wasting your time,in fact if your under 50 tons your wasting your time.
  • Techman Techman @ 3:46 AM
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    I've worked at factories that Megered every comp that was  3 phase, even 3hp refrig comps, but not 1 phase. Do ALL of your comps have SightGlass/MoistureIndicators,Head Press controls, CrankCase heaters,Pump down controls,Oil Failure Safety control( where required), EVERY electrical connection from the circuit breaker all the way to the comp terminals checked for tightness, WASHED condenser/evap coils and a few others to help extend the life of the compressors? I have/had comps last 28 years and one right now in its  mid 30's.I'm off to change out a comp right now on a "Dead Body" WI Freezer. Not people, not people (been there, done that), but for animals. That cond coil was really dirty! KindaSorta like 1+1=2.Did you put in HH (acid neutralizing) liquid/suction filter driers? Anyone know what "gack"is?
    This post was edited by an admin on March 20, 2014 4:14 AM.
  • Techman Techman @ 6:54 AM
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    Paul S , how did you make out?
    Why not megger 1phase comps across the board? I've never seen it done.
    This post was edited by an admin on April 6, 2014 6:58 AM.
  • N/A @ 8:32 AM


    3 phase it's a better than 1.
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