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Thread: question on Overload amps not matching motor draw

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    question on Overload amps not matching motor draw

    Okay so my Job has a filter dryer that keeps tripping the overload relay. My question is the thermal overload has a setting knob for the amps threshold, but it only goes up to 25 amps. But the compressor it is connected to says the nominal capacity is 14900w and the input voltage is 220V which it is actually getting 240V. But it says input is 5250w. So that means its normal amps it should be pulling is about 62 amps,right?

    So isnt this overload relay way to small for the compressor motor?
    Last edited by Skiroy; 06-04-2011 at 08:02 PM.


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    Community Moderator Al_The_Man's Avatar
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    Is it actually a 20HP motor?
    Is it fed from true 3ph or a RPC?
    Al.
    CNC, Mechatronics Integration and Custom Machine Design (Skype Avail).

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.


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    Quote Originally Posted by Al_The_Man View Post
    Is it actually a 20HP motor?
    Is it fed from true 3ph or a RPC?
    Al.
    True 3 ph and Im not sureif it is a 20HP.
    This is the dryer
    EMAX


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    Community Moderator Al_The_Man's Avatar
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    You need to determine the FLA, Full Load Amps of the motor and if necessary put a clamp on meter on each phase in turn to measure the actual current draw, especially if this is a new occurrence not previously seen.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design (Skype Avail).

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.


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    Registered vger's Avatar
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    I agree with Al on checking the amps in operation. The info sheet on that model says it should be 19 amps at 230 V. This will vary somewhat depending on a few conditions.

    Refridgeration compressor head pressure being too high can cause over current.

    Stopping and starting the Refridgeration compressor quickly can cause the compressor to stall causing VERY high current till the internal thermal protection kicks out.

    Make sure the condenser coils are clean. If the fins are clogged, the head pressure will run high as the freon does not condense back to liquid as readily.

    Steve


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