Capacitor check on furnace.

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Originally Posted by Hwolfe

I would check your amp draw on your motor after replacing capacitor to insure condition of the motor.

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Yes checking amps is a good thing, but I never check just amperage until after I have check voltage. :grin2:

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Originally Posted by Mr Bill

Yes checking amps is a good thing, but I never check just amperage until after I have check voltage. :grin2:

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Low voltage will make the amps climb... Then we find loose connections, and burnt wires, and well you know the rest.

CT

Changed cap ,motor hummed, gave blower spin to get going, noisy as hell, berrings are shot, going to replace motor. Thanks all for help.

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Originally Posted by iceage

Changed cap ,motor hummed, gave blower spin to get going, noisy as hell, bearings are shot, going to replace motor. Thanks all for help.

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Motor runs hot on low mfd. cap. washes oil out of bearings, possible scenario.

I would be careful saying a run capacitor's main job is to correct power factor.

I'd rather say the capacitor shifts the phase of one of the windings so that the voltage across the winding is at 90° from the other winding. The effectivly makes it a two-phase motor (when loaded).


Now if the proper capacitor is used......then the currents through each of the windings, when fully loaded, should be equal....and under those conditions power factor will be close to 100%.

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Originally Posted by Russ57

I would be careful saying a run capacitor's main job is to correct power factor.

I'd rather say the capacitor shifts the phase of one of the windings so that the voltage across the winding is at 90° from the other winding. The effectivly makes it a two-phase motor (when loaded).


Now if the proper capacitor is used......then the currents through each of the windings, when fully loaded, should be equal....and under those conditions power factor will be close to 100%.

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I agree 100%. In a nutshell, this is what I was trying to explain, but it did not come out as cleanly as you described. I was thinking about the phase angles and the reactance the capacitor adds to shift the angle.

Thanks for the input. My wordiness probably confused some readers.

CT

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Originally Posted by nsula_country

1.2 mfd vs 5 mfd? This is off 76% of a 5 mfd cap. Most caps are (+/-) 5%-10% tolerance. Change is good!

CT

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X2