Compressor motor keeps shutting off

[1930artdeco]

Just rebuilt my Wayne compressor and it has a new 1.5-2 hp Leeson motor on it. The flywheel is a 18” and weighs in about 15 lbs or more (guessing here).

The issue is that it runs for about 30 sec. And trips the breaker. And it is getting really hot. It is currently set up for 220 on a dual pole 20 amp breaker.

So dad thinks it is underpowered for the new rings and flywheel size. I have the motor that came with the original tank/pump combo. It is a Century 5hp, single phase 230 volt motor. However it only has one hot and one neutral wire.

My question is this:

1) I thought a 220/2240 volt motor should have three wires-2 hot and one neutral? Am I missing something-would not surprise me.

2) Will running with a 3450 rpm motor hurt the pump?

The original set up was 1.5 HP at approx. 900 rpm in 1941. But I also know those motors were torque monsters compared to today’s motors. I was just trying to stay within the original specs of the pump/motor combo.

Thanks,

Mike

 

[micromind]

220 is 2 hots, no neutral.

Since the old motor was 5HP and the new one is 2, it's grossly overloaded.

3450RPM is ok provided the pulley is the correct size.

 

[1930artdeco]

Sorry the original motor from 1941 was 1.5 hp. The tank I got came with a 5 hp motor. I added the 1.5 Leeson so that I could keep within the original 1941 specifications.

I will check the pulley size that I currently have. And if I have to get a new one then I will. I am just trying to keep the pump RPM’s down to the original specs.

So the black and white wires are both ‘hot’? Where is the return wire? The electricity has to return somehow.

Thanks,

Mike

 

[The Cobbler]

you're showing a 5hp motor, a 20 amp circuit is not enough for that.
240 volts is obtained by two 120 volt circuits out of phase from each other making 240 volts. but you do need a ground

 

[1930artdeco]

Ok, did not explain well. I have 40 amps total for the compressor. I have two 20 amp breakers dedicated for the compressor. Ok, so I do need a ground. So now I have to figure out where the ground/neutral wire went on this motor.

 

[1930artdeco]

Another wrinkle is that I did a temp wire for 110 just to see if it ran. And it ran. I expected it to run poorly due to it being 110 and not 220. But it ran fine. That and the lack of a ground wire makes me think it was rewired. Thoughts?

 

[The Cobbler]

I have 40 amps total for the compressor. I have two 20 amp breakers dedicated for the compressor.

no, you have a 20 amp 240 volt circuit , assuming you have the breakers on separate legs of the breaker panel.

 

[GeoBruin]

Another wrinkle is that I did a temp wire for 110 just to see if it ran. And it ran. I expected it to run poorly due to it being 110 and not 220. But it ran fine. That and the lack of a ground wire makes me think it was rewired. Thoughts?

I was going to suggest that it may have been wired for 120v and you only had two wires because you had a hot and a neutral but no ground.

 

[Wrench97]

Ok, did not explain well. I have 40 amps total for the compressor. I have two 20 amp breakers dedicated for the compressor. Ok, so I do need a ground. So now I have to figure out where the ground/neutral wire went on this motor.

Double pole breaker I hope?
That's still 20 amps not 40, 220-240v uses 2 110-120v legs no neutral.
European voltage is 230v single pole but 50hz not 60hz .

 

[1930artdeco]

Sorry I thought they were additive, as in two 20 amp breakers. Ok, so if I have 20 amps and the motor pulls 15 I should be ok. I now need to know how to ground the motor. Is it grounded through the case?

 

[Beerhippie]

Sorry I thought they were additive, as in two 20 amp breakers. Ok, so if I have 20 amps and the motor pulls 15 I should be ok. I now need to know how to ground the motor. Is it grounded through the case?

Yes, Just put a ring lug on the ground wire and use a star-washer under one of the screws securing the electrical box to the housing to attach the ground wire. The star-washer goes between the ring lug and the case to insure good electrical contact.

Triple-check to be sure you've wired the motor correctly--that's as likely to cause the breaker to trip as overloading is--especially if it's wired for 120V on a 240V circuit.

 

[1930artdeco]

Ok, I will check the motor over to verify that it is wired for 120 or 240. Then I will probably have to call the electrician back out. I know just enough to start a fire or kill myself. I just want to be safe. Thank you all for your help.

 

[Bert_]

Read up on some electrical theory. In a 240v circuit the power flows between the two hot wires. The ground is for safety only, no current should normally flow on the ground.

What you have pictured is really about a 3hp motor. The SPL is marketing code for BS.

If you have a pump from 1941 I would highly suspect that they would have used a 1750 RPM motor. You could use a 3450 but the motor pulley will have to be half the size of the original.

 

[Wrench97]

Read up on some electrical theory. In a 240v circuit the power flows between the two hot wires. The ground is for safety only, no current should normally flow on the ground.

What you have pictured is really about a 3hp motor. The SPL is marketing code for BS.

If you have a pump from 1941 I would highly suspect that they would have used a 1750 RPM motor. You could use a 3450 but the motor pulley will have to be half the size of the original.

Twice the size on the motor pulley or half size on the compressor.

 

[1930artdeco]

Just checked a calculator and my 4.5” pulley on the 3450 rpm motor will yield about 970 rpm on the 16” compressor flywheel. So should be good as long as I keep it under 1k at the pump.

 

[Bert_]

Twice the size on the motor pulley or half size on the compressor.

What? A motor pulley twice the size of original plus a 3450 motor would spin the compressor 4x the intended speed.

 

[Wrench97]

What? A motor pulley twice the size of original plus a 3450 motor would spin the compressor 4x the intended speed.

Woops you are correct I was thinking opposite.