Motor help?

[®smpr_fi_mac®]

220V, 1ph, 3hp DC blower motor

The other day a large chunk of wood got sucked in. The impeller jammed briefly. Motor got really loud as it tried to to turn. Chunk of wood dislodged, fell into collection bag. Steel impeller.

Now, when in try to start the motor it hums loudly and rocks back and forth. Trips the 30amp breaker after a few seconds.

If I spin the motor by hand and then turn it on, it runs, but struggles in the first few seconds before reaching speed.

Motor spins freely by hand and hose still has great suction when running.

I'm hoping it's only a bad start capacitor. If so, could that blockage have killed the capacitor?

[Roly]

220V, 1ph, 3hp DC blower motor

The other day a large chunk of wood got sucked in.  The impeller jammed briefly.  Motor got really loud as it tried to to turn.  Chunk of wood dislodged, fell into collection bag.  Steel impeller.

Now, when in try to start the motor it hums loudly and rocks back and forth.  Trips the 30amp breaker after a few seconds.  

If I spin the motor by hand and then turn it on, it runs, but struggles in the first few seconds before reaching speed.

Motor spins freely by hand and hose still has great suction when running.

I'm hoping it's only a bad start capacitor.  If so, could that blockage have killed the capacitor?

Yes,  the problem could also be the centrifugal switch, it is definitely in the starting circuit.  Look to see if the capacitor is bulging anywhere as that is most likely it since it was held in circuit too long.   Roly

[Bob Vaughan]

Yes,  the problem could also be the centrifugal switch, it is definitely in the starting circuit.  Look to see if the capacitor is bulging anywhere as that is most likely it since it was held in circuit too long.   Roly

Some of those cheaply made Asian motors have the centrifugal switch located under the fan shroud.  A sudden shock could dislodge the setscrew allowing the mechanism to slide up the shaft and prevent the contacts to disconnect.  The centrifugal switch on this cheap motor is located at the lower right.  As you can see, this motor is anything but totally enclosed, but it is easy to work on.

[attachment=37419]

[®smpr_fi_mac®]

I had it open when I replaced the bearings in it a couple months ago. I checked the contacts on the centrifugal switch; they were clean then. New capacitor showed up today. When I install it, I'll check the switch, too.

Thank you!

[®smpr_fi_mac®]

Okay, so I think it was the switch. It was located almost to the fan end of the shaft. I loosened the set screw and pushed the switch further down the shaft towards the motor.

Apparently too far, maybe?

Turned it on and the fireworks started. Lots of sparks being thrown from the switch. Tried turning it off, nothing.

Unplugged it from the wall and it started turning off, but not before the original start capacitor (which I haven't yet replaced) exploded, flying off the motor box with a puff of smoke.

Looking inside, the switch contacts aren't welded together so I guess that's good.

How close to the motor should the centrifugal switch be?

[®smpr_fi_mac®]

Oh, just figured out what the fireworks were from: the centrifugal body, as it spun, touched the contact, causing the sparking.

Obviously pushed in too far.

[®smpr_fi_mac®]

I think I found my answer!

https://www.google.com/search?q=how+to+a...P0LuIoAc19

[Bob Vaughan]

I think I found my answer!

Wow.  I looked at some of those videos.  They cover a lot of ground and a lot of different single phase motors but there are a lot more types they didn't cover.
For those Asian motors, I'll look for the circular print of the throw-out mechanism's setscrew.


[attachment=37428]

[®smpr_fi_mac®]

Yup, that's what I did, and then compared it to what they suggested; it was really close. Once reset and the start cap replaced, it runs great.

[MstrCarpenter]

Awesome knowledge shared here! And to think that all TEFC motors were in fact actually enclosed.