Need single phase motor help

[bob1112]

We bought a bowl tumber with a 1HP motor months ago and had problems with it over amping and tripping out about 1min after start. You could hear the motor slowing down and I watched the amps spike to over 50 and trip out. We pushed it aside until now.

I just took it apart and rewired the motor for 240V. It pulls 4.5A with no load on motor. Does this seem high for no load? that is like 1.5HP. Also, this motor seems to have some mechanical brake inside and not sure why. When I kill power to the motor, it will freewheel for a couple seconds and then clicks and it slows down fast. Has anyone seen a motor like this?

The motor, with no load, seems fine and stable. Not noisy and no heat. Just curious if there is something I am overlooking here? Can I check the coils in the motor with a meter to verify it is fine?

[Al_The_Man]

Re-wiring for 240 does not necessarily increase the HP, The stator/armature mass usually has to be increased.
Is this a 1ph motor?
But if you took it apart and rewound it you should have discovered any mechanism that it had inside, apart from a centrifugal start switch, if it is 1ph.
Other than that, there should be no other moving parts except the rotor.
Al.

[bob1112]

No, no, I just rewired the leads of the motor to operate at 240V to better balance leg loads in the shop. I understand that will not increase output. What I am worried about is why it is consuming 1.5HP with no load on it. I am sure that will be around 2HP with a load which means the motor is like 50% efficient.

Yes, the motor is a 1HP, 1PH motor. The thing is absolutely covered in grease so I am not excited to pull it and take it apart but kinda of seems like it is coming to that huh? I am wondering if the start cap will cause this when it switches back in? Is this normal for a 1PH motor?

[Al_The_Man]

Usually the cent switch goes open, this causes no-start issues, if it is welded shut, then it means the start windings are always on and causes increase in current.
To eliminate this, take the lead of the cap when up to speed, (use a jumper).
and see if the current decreases.
Al.

[bob1112]

Well i tested by bring motor up to speed and removing cap wire. Amperage stayed the same. On decel though, I did not get the braking effect as before, just could hear the cent switch coming back in and dragging on the armature. So the charging of the cap must be what causes the fast deceleration. Unless I can find that this 4.5A is way high for no load, I would lean towards a good motor on this one.

When I get an amperage spike, it climbs very gradually and the motor rpms just keep dropping. Pretty much like it is over loaded but that just does not make sense, since this is the OEM setup. Maybe the 240V swap will make it happy

[Al_The_Man]

I have a couple of 2 pole 1 ph motors in the shop and they draw 2hp/11amps 1 hp/5amps on 240, double that on 120v.
What does the FLA on the name plate of the motor state, and what is the rpm?
I would check the mechanics also as to if and why the motor is being loaded.
Al.

[bob1112]

Well if your 1HP motor pulls 5A at 240, then I should be in the ball park. I wish I knew FLA but no name plate to be found. This is a 4 pole motor. I tested at 1750 rpm with my tach.

One guy mentioned the amp draw is not accurate because of the in and out flow of power on the line. I am not sure on that one but I don't know of another way to test without putting some complicated diode, power sink device to test a motors draw without the return.

[Al_The_Man]

A clamp on ammeter is usually the 'cleanest' way to record the current.
If it is running cool and at a constant current at 1750 off load, then I don't think there is much wrong with the motor, if this is bogging down under load, I would look into the mechanical aspects of the tumbler, I know there is not usually a lot to them. Or try the motor on some other load, if possible.
Al.

[bob1112]

Well we got it! I still have no idea what was going on with 120V operation but the flip to 240V seemed to fix the problem. I just could not find any problems with any of the system so we will give this a go and see what happens. Current now looks to be 6.9-8.0A depending on how I set the counter weights.

I still think that is a lot of power for a 1HP motor but we will just have to go with it for now. The current stabilizes and even drops a bit after start when the bearing grease warms up a bit.

My biggest question now is should I add some more counter weight to get a bit more amplitude for finishing Al? Guess I might need to post in the other forums. thanks for all the help.