Air Compressor Tripping Breaker

[lordcupkake]

I just bought an air compressor for the first time. I have used them in shops, etc before but never owned my own. I bought a Porter Cable model cpf23400p-2 which is a 1.6 HP (3HP peak) compressor with a 4gal tank. I got it off FB marketplace. I have it running with a tee connector to an auxiliary 7 gallon tank as to run for a longer time with my compressor.

It runs great when you first turn it on from 0 psi. Starts right up and fills both tanks with no issues up to whatever pressure I set my regulator to. There is no issue there. Then, once it deems it has reached adequate pressure, it shuts off - again normal operation here. The issue becomes when I start using my tools and the pressure drops so the compressor kicks back on... when this happens I can hear the compressor chug and try to start then die. It dies because the breaker has been tripped. If I drain the tanks and untrip the breaker it starts right back up and works no problem again. But then same issue every time when it kicks BACK ON it trips the breaker. What is my issue here?

For reference, I am running it on a circuit with a 15amp breaker that has nothing else running on it. It is a dedicated 15A circuit.

 

[mfs54729]

Try cleaning the contacts on the pressure switch. My compressor started tripping the breaker and cleaning the contacts fixed the problem.

 

[The Cobbler]

sounds like you have an unloader issue
when the compressor reaches pressure & shuts off, you should hear a hiss while the head is unloading

 

[lordcupkake]

I also thought it may be an unloader valve issue based on some google searching. Where can I get a new one/how do I know if it will fit? Do I have to replace the whole pressure switch?

 

[The Cobbler]

the unloader valve is part of the pressure switch. it may or may not be replaceable. you might have to buy a new pressure switch.
snap some photos of the pressure switch . the unloader line will be about 1/4" diameter
it could be just bent or misaligned too

 

[sberry]

It needs a 20 breaker. No mystery.

 

[The Cobbler]

^^ first time anyone has suggested a 20 amp for a small pancake compressor ...

 

[MacMcMacmac]

There is a 1/4" line going from your check valve to the side of the pressure switch. When the switch opens, a small tab on the side of the contacts moves and depresses a small needle valve which bleeds air off from the check valve back to the cylinder head which allows for loadless starting. If you don't hear the hiss after it cuts out, this bleed valve is not working properly. Sometimes you can get lucky and slightly bend the little tab that works the needle valve, since it sometimes does not fully depress the needle. I have done this many times. You can buy these valves separate, but they are most of the price of a new pressure switch.

 

[lordcupkake]

It needs a 20 breaker. No mystery.

I was originally thinking that, but given that it runs fine from zero pressure and that the owners manual says the following (taken from the attachment, which is a screenshot of the manual):
"This air compressor can be operated on a 15 amp circuit if
1. Voltage supply to circuit is normal.
2. Circuit is not used to supply any other electrical needs (lights, appliances, etc.)
3. Extension cords comply with specifications in owners manual.
4. Circuit is equipped with 15 amp circuit breaker or 15 amp time delay fuse"
unfortunately I would just test it on a 20amp circuit but my 20amp circuits all have other appliances (fridge, dishwasher, etc) connected so I don't think they would even be better.

 

[lordcupkake]

There is a 1/4" line going from your check valve to the side of the pressure switch. When the switch opens, a small tab on the side of the contacts moves and depresses a small needle valve which bleeds air off from the check valve back to the cylinder head which allows for loadless starting. If you don't hear the hiss after it cuts out, this bleed valve is not working properly. Sometimes you can get lucky and slightly bend the little tab that works the needle valve, since it sometimes does not fully depress the needle. I have done this many times. You can buy these valves separate, but they are most of the price of a new pressure switch.

Based on the replies, I will try and mess with the bleeder/unloader valve tomorrow. I think this is most likely the culprit. I was hoping to avoid dropping 40$ on a new switch (Porter Cable's OEM price) if possible, so I hope I can just tweak it.

 

[vavet]

Before throwing parts at it, try an outlet on a different breaker. I had a similar issue several years ago. It turned out to be a circuit breaker problem. Apparently they wear as they age and don’t tolerate these amperage spikes when trying to start a stopped motor under load.
I replaced the 15 amp breaker with a new 15 amp breaker and it was fine after that.

 

[seber]

Not every compressor has an unloader. You may be trying to start the unit with full load power by design. Most modern circuits are 20 amp so the suggestion of a heavier circuit is not out of line. Check the owners manual.

 

[Ben Buck]

Check valve into the tank may be bad, allowing back pressure to push back- motor trips breaker .

If your using an extension cord- get the heaviest short one you can buy.

Take the air to the job- not the compressor.

Just my 1 1/2 cent worth- YMMV

 

[matt_i]

It needs a 20 breaker. No mystery.

I would also suggest this.

I was sitting at my PC when the lights went slightly dim and I hear a faint buzz from the circuit panel which sits below me in the house and I said WTF is the heavy amp draw?

I went to the shop and my 5hp/2stage compressor is running. I had forgotten to close the ball valve on the tank....

No breakers have ever been tripped, the wiring is all properly or over sized, but it occurs to me after thinking about it that the motor is 2 pole (3450rpm) and has minimum starting torque anyway.

Suppose the 1.6hp motor can draw 2x the FLA (full load amps) when starting. 1.6hp * 745W/hp = 1192W * 2 = 2384W / 120vac = 19.86A It doesn't pull that much for long but against the load of the mostly-filled tank I can see how it could trip a 15A breaker.

Its also very appropriate to check integrity of all connections. Flip off breaker and verify the screw is tight. Trace the neutral wire and make sure its tight on the bar. And all of the connections at the pressure switch.

 

[sberry]

These are marginal to start with. Rater at 1.6 hp. It's the reason they have 15 outlets on 20, headroom for starts. Test this before speculating on every scheme you can read about. Only reason they even list this for 15 is for sales.

 

[Citation]

This model does have an unloader valve integrated into the pressure switch
https://www.ereplacementparts.com/p...ake-air-compressor-parts-c-129_1662_2185.html
Look at parts 16, 62, 17 and the pressure switch where the actual unloader valve is located.

Looking at the pressure switch you should see the valve on the side (tube 17 goes to it). You should see the pressure switch push down on the top of the valve when the thing turns off.

Also, the pressure switch is almost certainly a universal part not mfr'ed by PC. Often you can get an exact replacement if you search for the part number on the switch. Note that there will be many that look the same. The differences are things like preset pressure ranges (these can be adjusted), with/without unloader, does the power cord come in the bottom or side, does the base have a single input or a 4 way base (where the pressure regulator, blowoff valve etc are all connected to the base of the pressure switch).

I don't think this is a 15 vs 20 A outlet issue. It might be a starter cap issue. If the cap it marginal perhaps it can start against an empty tank but not a pressurized tank. Still, I think the unloader is most likely.

 

[mengel]

I have a Industrial Air 1882054 (CH branded) that was supposed to run on 120V, but really couldn't. I tried a new breaker. The motor is just so close to the maximum current, I gave up and switched it to 240V. It works perfect now. I suppose I could put on a smaller motor pulley (stock 3" to 2.5") and go back to 120V someday.

 

[sberry]

It probably pulls 60-75 on start if everyhing is working just right. If it started tripping a 20 then it would be worth looking at other causes.

 

[The Cobbler]

an easy test, run the compressor up to full pressure. crack the unloader line ( loosen the nut) tighten back up. try to restart your compressor .
and you will be able to find a switch for much less, they are generic parts .

 

[kald]

Larger breaker!
Motors require a certain wattage to run.
Volts x amps = watts.
Also a unloaded motor vs a loaded motor will require more wattage to start as well.
For example if your motor rated current draw 15 amps @120 volts it needs 1800 watts.
Now if you have a voltage drop nder load from an extension cord or what ever then you may have something like this
1800 watts /105 volts=17.14 amps needed.

As was already suggested, get a bigger breaker.

 

[engineer2]

Since you bought it used, you might want to check the motor capacitors. Most folks don't have a capacitor tester. A motor shop would be able to check them. You could instead check the current draw while it is running. If it is abnormally high (above what's on the motor nameplate), you might have a bad run capacitor. We had one that was normally 21 amps. With a bad run cap is was 32 amps. Usually would trip the overload on the second startup.

 

[MacMcMacmac]

Unloader valve.

No hiss, no bliss....


It's also the easiest thing to check/alter.