electric motor capacitor

Discussion in 'Non-Automotive Stuff' started by Clark, Oct 26, 2017.

  1. Clark

    Clark In Maximum Overdrive

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    My Dayton garage exhaust fan (about 1/25th horsepower) died just after the one year warranty ran out. Out on the workbench, I find the fan bearings turn freely and the motor tries to run when powered (120V). I suspect the starting capacitor is bad.

    The capacitor is a two wire CBB61 5 microfarad unit. I found one on Amazon but apparently it is being shipped on a slow boat from China.

    Any chance I can replace this tiny capacitor with another? Even larger? Any recommendation?
     
  2. ribald1

    ribald1 In Maximum Overdrive PLATINUM MEMBER

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    Any capacitor of the same, or higher voltage rating with exactly the same capacitance will work.
    It just may not fit in the case.
    The capacitance has to be the same otherwise the reactance won't match the phase timing for proper starting. That would cause heating during starting and risk of insulation failure in the windings.
     
  3. Clark

    Clark In Maximum Overdrive

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    2,143
    Location:
    Brighton, Colorado
    Thanks ribald1. I figured you would know this.
     
  4. Clark

    Clark In Maximum Overdrive

    Messages:
    2,143
    Location:
    Brighton, Colorado
    Ok, finally got the correct capacitor but danged little motor still won't run. It spins freely by hand. It surges when I apply power but will not spin. Any other easy reason or must I replace it?
     
  5. ribald1

    ribald1 In Maximum Overdrive PLATINUM MEMBER

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    Location:
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    There are a couple of ways for a capacitor motor to start. A common way is a centrifugal switch to control the capacitor. It is usually on the end of the motor that is covered.
    They are pretty simple mechanisms, usually a spinning weight that pushes a ring away from the motor closing the circuit.
     

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