Induction Motor Question

[Lance Norris]

I recently bought a Jet 10-20 drum sander. It has a 1HP induction motor. It doesnt have an external capacitor. It also doesnt make the "click" that the centrifugal switch makes, so im assuming... no switch? Im just curious, because every other induction motor I have, has one or two caps and they also all have the internal switch...

It is a 1700-1725 RPM motor, does this have anything to do with the above question?

There is no problem, it comes up to speed quickly and has plenty of power, I am just wondering...

[John Lanciani]

Though I've never seen an asian motor without an inertia switch, not all single phase motors have them. On my European machinery (CEG motors from Italy) the start cap has a small relay built into it and a timer to drop out the capacitor a few seconds after it is energized. The capacitors are also mounted outside of the motor.

Every 1 hp motor that I've seen has had a start winding and capacitor so my guess is that the capacitor is buried somewhere inside of the motor and that the inertia switch is quiet enough that you're not hearing it.

Any chance that you could post a pic of the motor and the wiring diagram?

[Pete Bradley]

No cap on an induction motor usually means it's split phase. The nameplate may have more information on it. Not all centrifugal switches click, or it may have a different switch altogether.

For more on split phase motors, see:

http://en.wikipedia.org/wiki/AC_motor#Split-phase_induction_motor

[Lance Norris]

interesting... thanks