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  1. #1
    Join Date
    Apr 2011
    Location
    Nova Scotia Canada
    Posts
    7

    3 phase compressor ohm readings

    what is the cause or affect of a 3 phase compressor having diffrent ohm readings

  2. #2
    Join Date
    Mar 2011
    Location
    Nw.Connecticut
    Posts
    300
    How different less than .5 ohm ?

  3. #3
    Join Date
    Apr 2011
    Location
    Nashville,TN
    Posts
    102
    are you sure your ohming it correctly? a single phase will ohm out maybe like
    c-r=2
    c-s=6
    s-r=8
    but on a 3 phase example

    c-r=2
    c-s=2
    s-r=2

    make sure you turn off the power and pull of the wires!!

  4. #4
    Join Date
    Apr 2011
    Location
    Nova Scotia Canada
    Posts
    7
    yes, I checked it correctly. All wires off and no power. I don't remember the exact ohm readings but one was something crazy like 0 ohms then 14ohms and 24 ohms if I remember correctly.I have never seen this before.I compared this to identicle compressors on the rack and they all checked out o.k.When the comp. is started it trips the breaker immediately.I also cheched to ground.

  5. #5
    Join Date
    Dec 2008
    Location
    Ontario Canada
    Posts
    534
    if all wires were disconnected at the compressor and those measurements were taken at the bare terminals, then it sounds like you got it, bad compressor, they don't usually fail like that your right to be suspicious and double check

    voltage imbalance?

    bad contactor? (single phasing)

  6. #6
    Join Date
    Jan 2010
    Posts
    6,080
    Sounds like one winding is open to me.

  7. #7
    Join Date
    Apr 2011
    Posts
    28
    you need a new compresser.they sould all ohm the same

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