electric motor gets very hot after switching off

[Roy]

I have a newish bandsaw that I have only used for short periods until today when I was doing some repeat cuts and hence left it running continuously for about 30 minutes. After I switched off I noticed a hot electrics smell and the motor body had become too hot to touch. I therefore investigated further and notice that when it is running the air it blows over itself keeps it reasonably cool but on switching off the metal casing becomes progressively hotter. I haven't really noticed this on any of my other machines motors. Is this normal or could there be a fault with the motor, motor electronics or wiring. By way of further detail the stamp on the motor says it is by Electromotori, 250V, 7.71A, 1.1Kw. It has what I assume is a capacitor attached (Ducati 45uF). Any advice would be appreciated before I make a fool of myself with the manufacturers.

Thanks

Roy

[BigWallop]

It is normal for these machines to have fan cooling while the motor is running, but the point of it getting progressively hotter when it is switched off sounds a bit worrying. Is it being turned off properly ? Is it wired in properly ? Is it earthed properly ? Are the vent holes clean and clear of debris ?

It sounds as though the motor coil is still being supplied with electricity from somewhere, not enough to run the motor, so it might be the switch or plug that has been wired in wrong. Check them all before you plug the machine in again just to be sure.

[Pete C]

Hi,

Some cheap tools aren't rated for continous use, eg 30 mins on and 30 mins off instead.

cheers, Pete.

[OldScrawn]

Well it all depends. It could be a fault as the other poster said, but you might get a transient on the outside after switching off from the heat left inside the windings, which will probably be hotter than the outside when in operation. In operation, the air flow from the fan (and the rotor turning) will cool the inside of the windings. With the motor stopped, the easiest route out for the heat is probably outwards through the casing. For a domestic motor I would expect the outside to "peak" in a minute or so. If it is still hotter than the operating temperature after half an hour, then I reckon something is drawing current. Do you have a suitable AC ammeter, and the knowledge/confidence to use it?