So is the motor on this air compressor toast?

[kazlx]

I picked up a Champion 80 gallon to replace a small 60 gallon that I have been using.

Long story short, I wired up a magnetic starter, hook everything up and it runs for about 30 seconds when cold before the OL protections on the motor shuts the motor off. The motor seems to get pretty hot (to the point you almost can't touch it) in the very short time of running.

I've got 240V coming in to the magnetic starter from a 30A disconnect, 240V coming out when the starter is activated, so the motor is getting 240V. The motor is a single phase only 240V Emerson, no options to re-wire for other voltages. There's only two terminals inside the plate to wire to. Everything is wired with 10g wire.

Would I be correct in assuming the motor is toast, or is there anything else it could be? I'm guessing some sort of short internally?

 

[Davefr]

That symptom could suggest the start winding may not be getting disengaged after the motor starts. (maybe from a dirty or stuck centrifical switch)

That can damage the motor but hopefully the overload switch kicked it off in time.

I'd pull the motor's end cover and inspect the starting circuit.

 

[kazlx]

Sounds logical, but I don't have a clue what I'm looking at. Would it be something I would see with the cover off?

 

[C96]

I picked up a Champion 80 gallon to replace a small 60 gallon that I have been using.

Would I be correct in assuming the motor is toast, or is there anything else it could be? I'm guessing some sort of short internally?

If its not your centrifical switch as Dave mentioned, the run capacitor could be bad.

Also, you never mentioned the horsepower of the motor, or its FLA. Because of the size tank you mention, I’m going to guess its 5hp. It could still be starving for electrical power with the installation you have.

Depending on the motors nameplate rating, the electrical you have connected to the compressor now is bare bones minimum for a true 5hp motor under perfect conditions. Excessive voltage drop, condition of the compressor itself (pump & motor) ambient temperature etc. all put stress on the electrical feeding the compressor and thus can contribute to motor overload such as you are experiencing.

 

[Davefr]

Sounds logical, but I don't have a clue what I'm looking at.

You might want to take it to a motor shop if you have one around.

The wiring needs to be traced and tested. The caps needs to be tested and the centrifical switch should be checked to make sure it's breaking the start circuit. It's also a good idea to check the bearings and clean it up.

I've found that most motor problems are not fried windings. It's usually something much simpler and less expensive. These 5 HP motors are very expensive.

Unfortunately I don't know of a good DIY resource for electric motor diagnostics and repair. Maybe someone else knows of a good link with images.

 

[Hpozzuoli]

I fried the motor on my 60gal compressor 2 years back. I went to harbor freight and grabbed one of their 220volt motors for $120 at the time. 2yrs later and a ton of sandblasting and other heavy use that harbor freight motor is still working like a champ. Just an inexpensive option if you need to replace it.

 

[Davefr]

I fried the motor on my 60gal compressor 2 years back. I went to harbor freight and grabbed one of their 220volt motors for $120 at the time. 2yrs later and a ton of sandblasting and other heavy use that harbor freight motor is still working like a champ. Just an inexpensive option if you need to replace it.

The OP said he has a 80 gallon Champion compressor. I'm guessing it's 5+ HP. (maybe even 7.5HP if it requires a magnetic starter)

HF doesn't sell any motor near this big.

 

[Warrenator]

As stated by Davefr, to check the centrifugal switch, pull off the end cap and lubricate/move the linkage that you find in there and clean the contacts, that round mechanical spring loaded thing is the centrifugal switch. It should be able to move freely, the motor uses one set of windings to start and then once it is spinning the centrifugal switch opens and the other (running) windings are engaged.

 

[kazlx]

If its not your centrifical switch as Dave mentioned, the run capacitor could be bad.

Also, you never mentioned the horsepower of the motor, or its FLA. Because of the size tank you mention, I’m going to guess its 5hp. It could still be starving for electrical power with the installation you have.

Depending on the motors nameplate rating, the electrical you have connected to the compressor now is bare bones minimum for a true 5hp motor under perfect conditions. Excessive voltage drop, condition of the compressor itself (pump & motor) ambient temperature etc. all put stress on the electrical feeding the compressor and thus can contribute to motor overload such as you are experiencing.

You might want to take it to a motor shop if you have one around.

The wiring needs to be traced and tested. The caps needs to be tested and the centrifical switch should be checked to make sure it's breaking the start circuit. It's also a good idea to check the bearings and clean it up.

I've found that most motor problems are not fried windings. It's usually something much simpler and less expensive. These 5 HP motors are very expensive.

Unfortunately I don't know of a good DIY resource for electric motor diagnostics and repair. Maybe someone else knows of a good link with images.

It's a 5hp motor and the tag says 21.5 FLA. Not sure that the motor would need more power. If that's the case, I might have to look into running a dedicated circuit for it. I have a 50A circuit coming into the garage from a 200A panel. The 50A feeds all of my 220 plugs. I just wired in a 30A disconnect with TD fuses just for the compressor right off of the incoming J-box.

I found a local motor shop by my work that said they can take a look at it. I'm just trying to figure out if there is anything else I can address or eliminate. The motor surges before it trips the reset. The tank builds pressure relatively quickly from what I can tell, so I'm assuming the pump is is decent shape.

That being said, I don't mind spending some money on a motor, because even with a brand new motor, I'm still way ahead on what it would have cost me to purchase something like this new. I was just looking for something to replace my tiny 60 gallon for running my CNC plasma and some other air tools.

Also, for the magnetic starter, I guess it wasn't required, but for this size compressor, it seemed to be recommended, so I figured I would add one. I guess I could have just run right through the pressure switch.

 

[unashamedlaborer]

Not a good idea to rely on a pressure switch at almost 25 amps. Those little contacts aren't made for it. I've seen plenty of them welded closed. Also if your motor is a decent one it won't have any overload protection built In. Hence the overloads on the mag starter being very important.

 

[kazlx]

Not a good idea to rely on a pressure switch at almost 25 amps. Those little contacts aren't made for it. I've seen plenty of them welded closed. Also if your motor is a decent one it won't have any overload protection built In. Hence the overloads on the mag starter being very important.

That's what I figured. I decided the mag starter was a better way to go.

 

[unashamedlaborer]

Are you still looking for help with this motor or did you take it to a motor shop?

 

[kazlx]

I found a motor shop, but I'm guessing they are closed tomorrow and I probably won't be able to take it there until Thursday.

 

[jdcompman]

If its not your centrifical switch as Dave mentioned, the run capacitor could be bad.

Also, you never mentioned the horsepower of the motor, or its FLA. Because of the size tank you mention, I’m going to guess its 5hp. It could still be starving for electrical power with the installation you have.

Depending on the motors nameplate rating, the electrical you have connected to the compressor now is bare bones minimum for a true 5hp motor under perfect conditions. Excessive voltage drop, condition of the compressor itself (pump & motor) ambient temperature etc. all put stress on the electrical feeding the compressor and thus can contribute to motor overload such as you are experiencing.

I highly doubt this is the problem. I had 10 gauge running my 7.5HP Baldor on my Quincy running for hours on end while sandblasting without even a hint of a problem.

I'd look into the Caps and/or Starter switch as already stated.

 

[kazlx]

My buddy is an electrician and told me the motor is fine on 10. Too bad he doesn't live locally