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Thread: Have you ecer experienced a motor do this?

  1. #1
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    Have you ecer experienced a motor do this?

    I helped a coworker wire an indoor blower motor for a fan coil unit. When operating in the CCW position it over amps pulling 20 amps when it rated for about 8. It's a marathon 1/2 HP, 120vac. The internal overload is opening. It will ramp up and then down a couple of times then the overload that's it out. It will run all day as long as a load isn't put on it. It will operate in the CW position with the blower wheel not moving any air cause it's spinning the wrong direction all day. Just wondered if anyone else has experienced this with a new motor.

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    If you have 120V to motor, it's wired properly and cap is within spec it's a bad motor.
    I would double check everything, including motor spec before condemning it.

    You say ramp up and down but it doesn't sound like an ECM. No such thing as ramp up and down if it's not

  3. #3
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    Yeah I know it's bad.

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    So you wanted to know if anyone's gotten a bad motor out of the box before. Ok

  5. #5
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    No that's not I wanted to know. I ask to see if anyone has experienced a motor displaying a similar symptom, I assumed this was an area professionals only commented.

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    Peace and love brother, peace and love!

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    Quote Originally Posted by Ricky Dale View Post
    No that's not I wanted to know. I ask to see if anyone has experienced a motor displaying a similar symptom, I assumed this was an area professionals only commented.
    Lol..right.
    "If you can’t describe what you are doing as a process, you don’t know what you are doing." ~ W. Edwards Deming

    All those who wander..are not lost.

    Do NOT..mistake my kindness for weakness.

    The early bird may get the worm..but the second mouse gets the cheese.

  9. #8
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    Do you have the blower panel/door open while you're checking amp draw?

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    More info needed what kind of system, motor application?

    Sent from my SM-G900V using Tapatalk

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    No sir door is on and the unit is under normal operating conditions. the excessive amp draw is immediate. it's an indoor fan motor in a 4 pipe fan coil unit. The motor is bad out of the box just wondered if anyone has gotten one that did this. Bad internal overload, built incorrectly.

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    Every once in a while those little Chinese factory workers like to play funny little pranks like this on us dumb Americans. Ha, ha, looks like they got us again. Well played little Chinese dudes!

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  14. #12
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    Just found out issues with a 20 hp return fan that couldn't ramp up over 35%. Manufacturer put wrong rpm motor on the fan from the factory. Right HP, right make, just wrong rpm.
    Amperage way over at 100% speed. But I agree anything coming from China makes me suspect.

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    Sounds like the internal overload is fine...
    The construction of any electric motor stator is very precise, if there is a slight short between windings, between turns even, it will throw the entire thing off. Even if it ohms out ok, the defect may not occur until it is put under the thermal stress of actually running or running under a load.

    Don't forget that motors are dynamic and can behave differently in operation than what may be expected from meter testing. Not by design but because of defects. This happens with grounds too.

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    Quote Originally Posted by Ricky Dale View Post
    No sir door is on and the unit is under normal operating conditions. the excessive amp draw is immediate. it's an indoor fan motor in a 4 pipe fan coil unit. The motor is bad out of the box just wondered if anyone has gotten one that did this. Bad internal overload, built incorrectly.
    I had a trane condenser fan motor that way.

    Put a brand new motor in and it would just sit there and hum. It was getting the full 460 Volts and the run capacitor was good.

    Got another new motor and put it in and it was good.

  17. #15
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    No the internal overload isn't find that's what is opening to stop the motor before it cooks it's self. It's was wired incorrectly when it was built. Every now and then we get one that does crazy things cause it was screwed up on the assembly line.

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    Quote Originally Posted by Ricky Dale View Post
    No the internal overload isn't find that's what is opening to stop the motor before it cooks it's self. It's was wired incorrectly when it was built. Every now and then we get one that does crazy things cause it was screwed up on the assembly line.
    Nothing in your story has anything to do with the overload except that it is doing its job opening when the motor gets too hot.
    If that is what you're saying, I don't know how you think you can tell the symptoms are caused by an incorrectly "wired" overload. They are generally imbedded in the windings itself. Not many ways you can wire that incorrectly.
    If you mean the motor was wired incorrectly, the overload is working by opening!

    Don't mean to harp on this but saying an overload is bad because it's working is a lack of understanding of its function and is why people change parts unnneccessarily (not this case, of course):
    "Overload is open. Motor must be bad"
    Change motor
    "Same thing. Oh... The fan contractor was bad, single phasing the motor"
    Think further than the symptom!
    (Once again, not referring to OP, just the mentality of parts changers in general)

  19. #17
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    If the motor / blower was windmilling backwards when not powered up, you might see that extra high amp draw on a perfectly good motor trying to start against all of that extra load.

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    *Some overloads are snap-action discs mounted externally (but not serviceable)

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    Quote Originally Posted by BBeerme View Post
    If the motor / blower was windmilling backwards when not powered up, you might see that extra high amp draw on a perfectly good motor trying to start against all of that extra load.
    True...
    causes problems (over-amp and over-voltage alarms/faults) and necessitates extra programming changes for VFDs also (just FYI).

  22. #20
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    It wasn't wind milling backwards at any time. It would not operate with a load on it CW or CCW without tripping the 'internal" overload. A weak/bad or improperly overload when the 12 year old child labor kids made it. Thanks for you all's insight.

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