Compressor motor up in smoke????

shinnlinger · July 02, 2010, 10:10:17 PM

HI,

I have a 6 year old 240 volt 80 gallon Quincy compressor that is rated for 18 cfm with a big baldor motor on it. Yesterday, my daughter comes down and wants to "Help" by blowing off one of my tractors I'm about to paint. Anywhoo, as she is finishing up, I hear the compressor load up and it pops the breaker.

I think it might be seized, but I think that is odd as it is full of Amsoil and when I stick a screwdriver through the guard it spins freely, both the compressor and the motor. SO i go reset the breaker and it simple groans like it it frozen and pops the breaker again. I go turn the compressor itself off, reset the breaker again and then stick the screwdriver in to see if I can push it to start thinking a starter relay is bad or something, but same results, but this time with smoke coming from the motor.

I give up at this point thinking I will see what a new motor costs vs having the local guy rewind it. Well tonight, for shits and grins, I reset the breaker again and it groaned for a second, but then broke free and cycled normally.

NOw what? It seems to be working again, but am on borrowed time? Is there anything I can do in the name of preventive maintenance to prolong the motor or is it simply see what happens???

Thanks.

Dave

tyb525 · July 02, 2010, 11:01:15 PM

Our 80 gal does this sometimes too, but it's about 75 yrs old (with a newer motor). Can't say why. That amsoil can do strange things sometimes.

DeepWoods · July 02, 2010, 11:16:14 PM

I have had a similar problem with my 60 gallon compressor ever since we moved. It sometimes trips the breaker as it shuts off. But I think the unloader is the problem. Once I reset the breaker, it seem to start just fine. I have never let any of the magic smoke out of the motor, so I think I have been lucky so far. I'm not sure what to fix with the unloader as I have never worked on one before. Any motor that has lost some of the magic smoke that I have had didn't last long before it quit working completely.

trim4u2nv · July 02, 2010, 11:37:20 PM

Make sure you check your unloader valve and positive check valve also. This can overload the motor on startup.

SPIKER · July 02, 2010, 11:42:06 PM

sounds like a start capacitor has gone out on it, there should be a can on the side of the motor, sometimes the wires will come off but usually the cap pops and then the phase shift that kicks the motor to start and run wont work the motor wont have the power to get the system moving up to speed. the slow motor then draws excess current and trips the breaker as well as blows the magic smoke out as the windings overheat

some may have start and run caps on them 2 of similar sized. there is also a switch (speed switch) usually on the ends of the motor that kicks the cap out once the motor comes up to speed. the switch often can stick get dirty and not come back in once it has kicked out.

Mark

shinnlinger · July 03, 2010, 06:45:41 AM

Thanks!!!

Should I pull the cover and blow things out and look at my valves? How do I know if my "unloader valve" and "positive check valve" is working correctly???? WHere are these valves located?

Dave

trim4u2nv · July 03, 2010, 07:17:27 AM

Unloader valve is usually inside the pressure switch has a smaller line that connects between the compressor and tank. This dumps air in the line between the compressor and the check valve so the motor doesnt start under load. At pressure switch cutout (when the tank is at pressure) the unloader valve opens on cutout. The positive check valve is usually on the bigger line closer to the tank end. This prevents air from leaking from the tank to the compressor exaust port. Sometimes the bigger line has cooling fins on it to increase performance.

Larry · July 03, 2010, 08:01:41 AM

When the motor stops, you should hear a air hiss as pressure is released by the unloader valve from the compressor. It should only last for a few seconds.

shinnlinger · July 05, 2010, 02:18:59 PM

Ok,

Went out and took of the pressure switch cover and had a look see. Everything looks good and I can hear air hiss when it ends it's cycle so I am guessing the valves are OK.

The compressor seems to be fine now and I am a fan of "if it ain't broke don't fix it", but at the same time, I am sure a compressor duty 5 horse baldor ain't cheap, so what to do???

Dave

trim4u2nv · July 05, 2010, 04:38:57 PM

I've had a few obscure problems like this. Make sure you air filter is not disintegrating. If pieces of the air filter get through the check valve or unloader valve, they can partially block or stick valves causing a loaded pump. Sometimes the check valve gets gummed up with oxidized oil and sticks also. Also low voltage can cause problems at start because this is the highest amperage at pump startup. Too many air conditioners running at once?

shinnlinger · July 05, 2010, 08:36:14 PM

Thanks,

My filters look new and I don't have any AC... don't really need it up here, but this week I might reassess that. Are both of these valves under the plastic pressure switch cover???

Dave

trim4u2nv · July 06, 2010, 12:36:56 AM

The check valve usually is half in and half out of the tank.
Click link below and click check valve for a typical valve

http://mycompressorparts.com/

Magicman · July 06, 2010, 09:53:35 AM

Bad thing about problems that fix themselves, is that you are always waiting on the next gotcha. It takes a long time to really trust it again.

terrifictimbersllc · July 06, 2010, 10:43:30 AM

Make sure your wire gauge to compressor is plenty big, a size larger than what is called for for the given length and startup amperage is not a bad idea. Can burn out a motor over time with just barely sufficient wire size.

Swede · July 11, 2010, 06:17:23 AM

I´m not shure what type of compressor You have. Most solutions You´ve been told here but talking smoke from the motor..........

I guess the smoke came from the box on the motor. If it´s 3-phase, You sometimes miss one phase, when the compressor is working connection is sufficient. Check all nuts and screws holding wires, also other points in the main circuit. If there is black dust anywhere You´ve find a bad point.
A 3-phase relay can also (wholly or partially) lose one of 3 phases, (temporary or for ever) can be hard to find.

Swede.
www.maskinochtryckluft.se

shinnlinger · July 12, 2010, 10:32:43 PM

Thanks for the replies guys.

I have 6 gauge wire on the unit as that is what I had laying around at install and it only is a 30 amp 240 volt single phase circuit, so I should be fine there. Air hisses at the end of a cycle so I think the valves are OK. THe filters look good and every thing turns freely and did at the time of the stall even, Today I put a meter on it and sees that it draws between 19 and 20 amps and the motor is rated for 21 so it appears to be totally fine.

So now what? the compressor is located in the barn and I am usually running air nailers and what not as I am building my house 300 ft away, so I usually can't hear what it is doing. I am continuing to use it as I need to, but it would be nice to know I am not damaging an expensive tool thru neglect.

Dave