start capacitor


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Old 08-05-08, 07:01 AM
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start capacitor

The pump motor for my pool filter hums when I try to start it. I know it's probably the start capacitor. I've done some work with electronics before but never done anything with single phase motors. The motor is 115/230V 1.5hp and has a 3 terminal start capacitor. Two yellow wires and a red one. Is there any order to removing the wires since it might be charged? Also I read somewhere they should be discharged before removing. thanks
 
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Old 08-05-08, 07:13 AM
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Make sure ALL power is definitely off. Short the leads of the capacitor together - all leads - but it is unlikely there will be any charge. I assume you are replacing the capacitor?

You said 115/220. It is either wired for one or the other. Also the rotor cold be locked up for another reason, like a bad bearing but this would likely blow the breaker fairly fast.
 
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Old 08-05-08, 07:22 AM
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Nothings locked up. Spins freely. I can get it to start if I keep flipping the switch which leads me to believe it's the capacitor. Like I said, I never worked with large capacitors before so I want to be careful not to short anything or get zapped.
 
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Old 08-05-08, 11:45 AM
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Removed and tested capacitor. It's bad. I'm curious. Why aren't the terminals of these start capacitors labeled positive and negative? Does it matter which wire goes on what terminal?
 
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Old 08-05-08, 12:34 PM
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No it does not matter. AC motor start capacitors have no polarity as AC has no polarity.
 
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Old 08-05-08, 12:48 PM
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Ah. Makes sense. Installed new capacitor. Back up and running. Thanks
 
 

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