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[Closed] Anyone know anything about single phase capacitor start induction motors?

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My planer-thicknesser hasn't been used for a number of years. Dragged it out today and it refused to start. It did turn slowly a couple of times and then ran but with no power at all. and then wouldn't even start to turn. I removed the motor and it will start fine on the floor with zero load but even the slightest touch with your toe and it will fail to start spinning. Also noticed that when it does run it sometimes goes clockwise, and sometimes anticlockwise. Could it be that the capacitor has packed in, or will it be something in to the motor itself? Any ideas gratefully received.

wf


 
Posted : 01/06/2020 9:47 pm
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Something about 88mph...I think...


 
Posted : 01/06/2020 9:49 pm
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High probability it is the cap, you should be able to get a replacement cheap enough online.


 
Posted : 01/06/2020 9:50 pm
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Not a clue about that but in the Hifi world usually if there is an electrolytic capacitor somewhere its to blame. Usually last for years and years but if you have Friday evening job I've seen them fail within 5 years.

So replacing the cap might be a good shout?


 
Posted : 02/06/2020 12:38 am
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in the Hifi world usually if there is an electrolytic capacitor somewhere its to blame

Whatever the world, if the caps are of Noughties vintage then this is highly likely. There is a vast number of caps out there full of shit electrolyte thanks to a curious tale of industrial espionage.

And if they're much older than that, they tend to die of natural causes eventually anyway.


 
Posted : 02/06/2020 1:14 am
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Some single phase motors have run capacitor as well as a start cap. Quite often with start caps gone the motor run ok but need a push start. Your symptoms sounds like run cap. If there is just one cap it's probably a run / start cap combined. Whichever it is make sure you get one of the same farad rating. This is what produces the phase shift to give torque. The voltage is less important as long as it is as high as what it on there already.


 
Posted : 02/06/2020 6:06 am
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P.s if it is only a start cap there is usually a relay that clicks off as the motor increases in speed.


 
Posted : 02/06/2020 6:22 am
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I had to replace the capacitor in the pump motor that I use to feed the shower. It was straightforward and cheap, I just bought another capacitor of the same spec from ebay.


 
Posted : 02/06/2020 6:43 am
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All very helpful and reassuring. Thanks for all the comments peeps

Ps bought new around 2002


 
Posted : 02/06/2020 7:04 am
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Just to close thread. Finally got around to checking out the capacitor and found that it had melted/ destroyed itself inside. Found a similar one on eBay for about six quid and fitted it this morning. And we are back in business. So thanks for the help. Job jobbed


 
Posted : 09/01/2021 11:48 am
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Sometimes there is a centrifugal switch ( on lift pump motors we have them) on the the switch can be fault or the contacts need a cleaning.


 
Posted : 09/01/2021 12:03 pm

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