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  1. #1
    Join Date
    Oct 2003
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    ICM 402 Phase monitor

    Techs and Techettes,

    ICM makes an "economical" phase monitor, the above mentioned ICM 402. I put a boatload of these in a plant about 6 years ago. Been online since then. Recently, a couple of the refrigeration units have been kicking the oil failure mysteriously. All is well, net oil and contactors OK. No pressurized crankcases, etc. Wiring checked and the units watched coming out of defrost etc. Here is the question: I noticed that on the two units that are cutting of on oil fail, that the ICM 402 green light is considerably duller than other units that are onsite. Could there be a connection? Control and line voltage OK at both units and at the control. Thanks in advance.


    r404a

  2. #2
    Join Date
    Jan 2002
    Location
    Fayetteville, NC
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    133
    Have you checked the compressor oil screen yet? What type of oil fail? Sentronics or mechanical? Do you have any pressure drop across the suction felts? Any flood back washing out the oil? There are more questions but I'm sure others will bring them up.

    As a basic test of the phase monitors, switch a non oil failing one with a oil failing one. If the problem follows you know its the phase monitor. A monitor trips and opens the contactor or control circuit. Unless the contactor is not pulling in due to a monitor problem I can't see it being the issue.

  3. #3
    Join Date
    Jan 2006
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    Quote Originally Posted by Txvman View Post
    As a basic test of the phase monitors, switch a non oil failing one with a oil failing one. If the problem follows you know its the phase monitor. A monitor trips and opens the contactor or control circuit. Unless the contactor is not pulling in due to a monitor problem I can't see it being the issue.
    I'm in total agreement here. Typically, if the phase monitor senses trouble it will open the control circuit which would take the compressor out via the contactor (and would have not effect on the oil safety).

    Current sensing relays wired into the compressor control circuit would rule out an oil trip due to electrical problem.

    Sentronic controls can sometimes act up. I'd start with Txvman's recommendation and change monitors (you may want to swap oil controls too if they are sentronics).

  4. #4
    Join Date
    Oct 2003
    Location
    tidewater, va
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    Net oil is good, no floodback at start up or after defrost. Market Tech, what do you mean by an oil failing type 3 phase monitor? Reason I think it could be an issue, is if the 3 phase monitor starts cutting in and out several times, I could be timing out on oil fail. I have not seen it happen, however. It is a mechanical oil failure switch. Thanks for the replies.


    r404a

  5. #5
    Join Date
    Jan 2002
    Location
    Fayetteville, NC
    Posts
    133
    Ummm...I reread the posts and did not see anything on a "type 3 oil fail". You know I rethought my post. If all the safety's are in series, including the monitor, then the monitor can't be the problem. Just like if a hi/low pressure control tripped it would not time out the oil fail. If something was wired wrong then maybe.

    I still come back to switching out the monitor, checking the compressor screen, is the oil separator float sticking?, suction felts, whats the oil level?, oil float sticking?
    Last edited by Txvman; 05-28-2007 at 12:19 PM.

  6. #6
    Join Date
    Jan 2006
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    DFW Metroplex
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    Quote Originally Posted by r404a View Post
    Net oil is good, no floodback at start up or after defrost. Market Tech, what do you mean by an oil failing type 3 phase monitor? Reason I think it could be an issue, is if the 3 phase monitor starts cutting in and out several times, I could be timing out on oil fail. I have not seen it happen, however. It is a mechanical oil failure switch. Thanks for the replies.


    r404a
    I don't recall stating anything about a type 3 phase monitor.

    Personally I have never seen a phase monitor "chatter" - most times they just flat out fail.

    Mechanical oil switches are quite reliable and if you suspect the phase monitor is short cycling the compressor it may very well be possible that the compressor is tripping on internal overload protection.

    If you had a current sensing relay installed in your compressor control circuit the chance of a false oil trip due to an electrical problem would be eliminated since the relay would take out the oil control as soon as compressor amps were no longer sensed.


  7. #7
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    Oct 2003
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    tidewater, va
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    Market,

    Thanks for the replies. What is the PN on that current sensing relay? I have had internals locking a comp out before in the same scenario that you mentioned.

    Thanks alot


    404

  8. #8
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    Jan 2006
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    I think its a Copeland 940-0135-01.

    The one pictured is just a relay I grabbed off a website.

  9. #9
    Join Date
    Oct 2005
    Location
    Florida
    Posts
    18

    boschunter

    Recheck the control circuit. Something is wrong there. The duller light is indicating an electrical issue and It sounds like your circuit is backfeeding. From my experience I would check for a loose or partially burnt wire somewhere.

  10. #10
    Join Date
    Dec 2004
    Location
    Mid-west
    Posts
    567
    Is the phase monitor manual reset or auto, I've never seen one chatter without locking out. If its auto reset switch it to manual to see if that stops the oil failures.

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