Capacitors on induction motor tools

May 12, 2004 5 Replies

I've had two tools die on me in the last fortnight. The first was a cement mixer and the second a table saw. Both had induction motors and in both cases it was the capacitor that supplies the starting torque that failed... an acrid smell followed by a humming and a failure to rotate, cured by a shove to the blade or barrel.



Both tools were under guarantee and the manufacturers were happy to put spare capacitors in the post but since I generally take care of tools and don't recall overloading either of them, I was wondering what put the kibosh on the capacitors in the first place?



The mixer manufacturer said that the capacitor should cope with a full load from a standing start even though they recommend starting the drum empty.



Is capacitor failure a general problem with induction motors?



Mike


Were you at the time starting them frequently? The capacitor is not rated for the continuous starting current, just intermittent.

They can also dry out over time.

No. Are you running them from mains or a generator. If the latter suspect this isn't performing to spec.

Thanks for the reply.

Yes, they'd been started fairly frequently at the time. The table saw is a cheapie but I'd have expected the mixer to be made of sterner stuff.

Thanks for the reply. They're both being run from the mains.

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