Electric Motor Problem

[paulrockliffe]

I'm sure someone will be able to help with this, I have a motor that runs slow, it's from a 240v single phase garden shredder.

I've tried Google and done some tests; the motor runs slowly as it is, removing a lead from the capacitor lets the motor run flat out again. But Google isn't clear (because I don't understand motors!) whether that means the capacitor is broken or whether there's a centrifugal switch on the motor that's stuck.

Can any experts advise? I don't want to buy a capacitor if that's not the right answer. Also if it's the centrifugal switch, can I sort that easily and without taking the motor to bits?

Thanks!

 

[Myfordman]

I'd expect a shredder motor to have no centrifugal switch as it needs high running torque but neglible starting torque.
Therefore I think the winding connected to the capacitor is probably damaged.
You could use it with a push button to connect the capacitor when starting only but bear in mind the running torque will likely be reduced.

 

[sunnybob]

if you remove the capacitor, I'm 90% sure the motor should not start.
Does it?

To my semi experienced brain I think the capacitor value might be wrong. Did it use to work ok?

 

[paulrockliffe]

Thanks, it used to work fine. It got jammed a few times and although I turned the motor off immediately it refused to start, no hum or anything, then started to run again, but only slowly.

I thought the motor wouldn't start without the capacitor, but it does and it spins much faster than with the cap connected. That might be because when I've got the machine stripped to test it it's only spinning the spindle, rather than the weight of the chopper bit. I'm not going to test whether it still starts with all the bits put back on unless I really have to though.

I can't see any damage to the motor windings, but I don't really know what I'm looking for and I can't see all of the winding.

 

[sunnybob]

I'm not skilled enough to tell you definitely, but from my experience I would try another capacitor as they are not very expensive.
Or use yellow pages to find a motor rewind shop near you.

 

[paulrockliffe]

Capacitor arrived, plugged it in and it sounds like we're back up to speed, so thanks for the help. Looking forward to clearing my drive of crap tomorrow and getting the rest of the mulch on the raspberries!