Air Compressor - Breaker Tripping off

[rshiggaon]

Hello - I have a weird issue going on. My Air Compressor circuit breaker keeps tripping. As soon as I reset the breaker, it works but trips out after some time. The issue first surfaced 3-4 months back, reducing the threshold PSI when my air compressor stops and replacing the breaker with a higher (40) AMP seemed like the problem was resolved. But this week the issue resurfaced again. I then replaced the wire that connects the air compressor to the electric wire in the conduit, thinking something was wrong but that did not help. The electrician that I talked to for help, doesn't think the wire in the conduit is an issue as the air compressor runs once reset.

Any pointers to debug this issue? TIA

 

[Randy]

Replacing the breaker with a higher amp breaker is about the worse thing you can do. What kind of air compressor is it and what's the voltage? You've got a motor issue. It's either the start switch in the back of the motor or the start capacitor. Take the motor to a motor shop and have them test it or just replace the motor.

 

[rshiggaon]

Replacing the breaker with a higher amp breaker is about the worse thing you can do. What kind of air compressor is it and what's the voltage? You've got a motor issue. It's either the start switch in the back of the motor or the start capacitor. Take the motor to a motor shop and have them test it or just replace the motor.

Thank you, I knew something is not making sense.

How do I know if the start switch or start capacitor is wrong? What kind of motor shop you are talking about?

 

[Randy]

Thank you, I knew something is not making sense.

How do I know if the start switch or start capacitor is wrong? What kind of motor shop you are talking about?

How old is the air compressor? Who's it made by? You should take the motor to a shop that specializes in electric motor repair, but most of the motors now are throw aways. I'd probably just buy a new motor.

 

[MEP001]

If this is happening more when it's cold, the motor is probably failing. Also listen to it when it shuts off, there should be a blast of air. That's a valve to let the compressor start with no load.

 

[Greg_T]

Agreed - sounds like a motor issue. Other fixes are "papering over the cracks".

 

[rshiggaon]

How old is the air compressor? Who's it made by? You should take the motor to a shop that specializes in electric motor repair, but most of the motors now are throw aways. I'd probably just buy a new motor.

It is a North Star Air Compressor, attached are the specs of the compressor. The breaker is 40 AMP. The seller that we brought this car wash installed it in 2021. My tech guy mentioned that it cannot be the compressor but the wire that is connected to the breaker, is not thick enough to hold this electricity.

I am confused about what should be the next step to get my car wash working.

TIA

 

[MEP001]

My tech guy mentioned that it cannot be the compressor but the wire that is connected to the breaker, is not thick enough to hold this electricity.

If that was the case, it would not have worked since 2021.

Has this been happening more since it's gotten cold? Do you find it tripped in the morning? If so, try changing the compressor oil with a good synthetic one and see if that helps. Load test the motor to see if it's running above 40A once it gets started. The startup amps will be significantly higher which is normal. Check your voltage, a lot of washes are wired for 208V, which increases the amperage, and you'll need a bigger breaker. Check the wire to the compressor, which should be 8 gauge. Ideally there should be no wire connections between the breaker and the compressor, and if there are it should be made with lugs and not wire nuts. If all this looks good, the breaker could be failing.

 

[rshiggaon]

If that was the case, it would not have worked since 2021.

Has this been happening more since it's gotten cold? Do you find it tripped in the morning? If so, try changing the compressor oil with a good synthetic one and see if that helps. Load test the motor to see if it's running above 40A once it gets started. The startup amps will be significantly higher which is normal. Check your voltage, a lot of washes are wired for 208V, which increases the amperage, and you'll need a bigger breaker. Check the wire to the compressor, which should be 8 gauge. Ideally there should be no wire connections between the breaker and the compressor, and if there are it should be made with lugs and not wire nuts. If all this looks good, the breaker could be failing.

We replaced the oil 4 months back, but I will check the other steps you have called out. Thank you.

 

[STXCW]

A 230V single phase motors on a 208V system suck in my experience. At a busy site, you will be lucky to get 2 years out of one.

 

[MEP001]

A 230V single phase motors on a 208V system suck in my experience. At a busy site, you will be lucky to get 2 years out of one.

Yeah, the extra heat kills those cheap Chinesium motors most of the compressor manufacturers use. I may switch to good 1750 RPM motors with a pulley sized to run them at about 75%.

 

[Randy]

Yeah, the extra heat kills those cheap Chinesium motors most of the compressor manufacturers use. I may switch to good 1750 RPM motors with a pulley sized to run them at about 75%.

Speed kills most air compressors. Manufacturers run them at a high speed to get more CFM’s out of the pump. That high RPM builds up the heat that kills off the compressor and makes a lot of water. I have a 29 year Sanborn that runs at around 550 rpm and makes plenty of air for the car wash. I have an IR compressor that I replaced the 4” pulley that was on the motor from the factory and put on a 2 ½” motor pulley. When it had the 4” on the motor it would scream, now it chugs along and makes enough air for the car wash. A lot of the compressors on the market from the big box stores are made by MAT Industries LLC, they just change the labels and the color. If you look at them very closely they all for the most part use the same components, for the most part they are all made in China.

 

[Twodose]

if your not using a magnetic motor starter, it is a good idea to have one.

 

[Rudy]

An often overlooked issue.....involves the unloader valve. After the pump fills the tank, the pressure switch stops the motor, and SHOULD relieve the pent up pressure in the air line between the pump and the tank. This is so that upon restarting, the pump doesn't have to overcome high pressure.

Do you hear a "hiss" when the pump turns off?

If not, you probably need a new unloader valve (which is usually incorporated into the pressure switch).

 

[rshiggaon]

If that was the case, it would not have worked since 2021.

Has this been happening more since it's gotten cold? Do you find it tripped in the morning? If so, try changing the compressor oil with a good synthetic one and see if that helps. Load test the motor to see if it's running above 40A once it gets started. The startup amps will be significantly higher which is normal. Check your voltage, a lot of washes are wired for 208V, which increases the amperage, and you'll need a bigger breaker. Check the wire to the compressor, which should be 8 gauge. Ideally there should be no wire connections between the breaker and the compressor, and if there are it should be made with lugs and not wire nuts. If all this looks good, the breaker could be failing.

Here is what I have figured till now: -
- The wire gauge is not even 10. So we plan to change it to 8 so that it can hold 40A.
- We see the voltage is coming to 208V, I don't think so changing the wire gauge will improve this voltage.
- We plan to change the wire gauge and do a test load. If required we will change to a bigger breaker.

Also, my electrician is mentioning that my compressor requires 240V, given we have 208V it may burn out soon. He was asking to change the compressor that works with 208V or put in a transformer. My idea is to keep it running as it is, and see what happens. Any expert advice?

 

[MEP001]

You don't need a transformer. A 240V motor can run on 208V, it will just draw more amps. Bigger wire alone may solve it, and if it doesn't you can go to a 50A breaker.

I've mentioned twice about cold weather. Do you find it tripped in the morning? I had a compressor failing like this, and I got by a couple weeks by leaving the drain a tiny bit open so it would come on every 15 minutes and kept the compressor pump warm. It would trip the breaker when the pump got cold overnight and it was too stiff to start.

 

[rshiggaon]

I am not sure when it trips off. We have seen this issue first in late summer (when it was not cold) and now (for sure in the evening).

 

[Randy]

I found the manual online and it says on page 14, “This unit must be connected to a 230V circuit with a minimum rating of 40 amps. Do not use this unit on a 208V circuit of any kind.” Look at the label plate on the side of the motor and see if it can be wired to run on 208 volts. You may have to replace the circuit breaker again and go up to a 50 amp and make sure you have 6AWG wire feeding the air compressor. Check to see how many amps the air compressor is drawing when it starts. Here’s a link to the manual if you don’t have it. https://www.northerntool.com/images/downloads/manuals/459242.pdf
How big was the first circuit breaker that you replaced? What size wire do you currently have feeding the air compressor?

 

[Zal]

Not unloading after shutdown seems likely. I had a cheap harbor freight compressor start on fire when pressure switch/unloader failed one too many times

 

[MEP001]

I had a cheap harbor freight compressor start on fire

I'm sure you're not the first person to say that.