Air Compressor problem,

[dennisoates]

My two year old Porter Cable 2 hp motor is having a problem. As the compressor reaches max shutoff pressure of 155 lbs it pop the breaker. I see sparks on end of motor near brushes. It runs fine until it gets close to max pressure. I have new capacitors on it. what causes this breaker to pop? I have also tried other outlets.
thanks

 

[Jswain]

Sounds like it is drawing too many amps at full load. If you have a clamp meter throw it on one of the leads & check/compare with motor for FLA. I would test the capacitors even tho they are new because if one of them is bad it will do this, also check all the wiring & make sure you are getting the proper voltage & have solid connections

Could also remove belt and ensure both pulleys spin freely

 

[seber]

First determine whether it has brushes or capacitors. I can't imagine how a motor could have both. If it is a capacitor start, capacitor run as I suspect and you are getting sparks in the motor, check that spot. It could be a bad connection or a bad contactor.

 

[The Cobbler]

if it has brushes & they are sparking , and blowing the breaker I suspect a bad armature .
I had a small senco compressor for trim that stopped running and it was a bad connection at the termination of the windings inside the motor. a cut off crimp terminal and some shrink wrap fixed it lickity split

 

[whateg01]

Did you replace the caps because of this? Or did this start after replacing the caps? Why were the caps replaced?

 

[dennisoates]

Sounds like it is drawing too many amps at full load. If you have a clamp meter throw it on one of the leads & check/compare with motor for FLA. I would test the capacitors even tho they are new because if one of them is bad it will do this, also check all the wiring & make sure you are getting the proper voltage & have solid connections

Could also remove belt and ensure both pulleys spin freely

I did the clamp meter test, and the amp are fine until the pressure guage goes to 145lbs. then the amp skyrocket and the breaker snaps. I checked all wires , i don't have a capacitor tester, would a bad run capacitor cause this?

 

[dennisoates]

Did you replace the caps because of this? Or did this start after replacing the caps? Why were the caps replaced?

they were replaced because the breaker was snapping? I took the motor to a Electric Motor repair place, so i thought it was fixed.

 

[dennisoates]

First determine whether it has brushes or capacitors. I can't imagine how a motor could have both. If it is a capacitor start, capacitor run as I suspect and you are getting sparks in the motor, check that spot. It could be a bad connection or a bad contactor.

it has two capacitors

 

[dennisoates]

Did you replace the caps because of this? Or did this start after replacing the caps? Why were the caps replaced?

they were replaced because the breaker was snapping

 

[Citation]

You might take a look at the centrifugal switch in the motor. Perhaps it's getting stuck on/in the start position.
The switch is located where you might find brushes in a universal motor. Since this motor has capacitors I'm assuming it's actually an induction motor.

Electric Motor Centrifugal Switch / PTC / PRD How it works to cut-out the motor starting capacitor

Electric Motor Centrifugal Switch / PTC / PRD How it works to cut-out the motor starting capacitor

inspectapedia.com

 

[whateg01]

they were replaced because the breaker was snapping? I took the motor to a Electric Motor repair place, so i thought it was fixed.

Well, assuming the motor shop tested the motor, it was probably not with a heavy load. If it's an induction motor, there should not be any sparks after it's been running like that. I would suggest maybe taking it back to the shop and letting them know it's still acting up but only under a heavy load.

 

[dennisoates]

do you think the pressure regulator would cause this problem?

 

[dennisoates]

Sounds like it is drawing too many amps at full load. If you have a clamp meter throw it on one of the leads & check/compare with motor for FLA. I would test the capacitors even tho they are new because if one of them is bad it will do this, also check all the wiring & make sure you are getting the proper voltage & have solid connections

Could also remove belt and ensure both pulleys spin freely

do you think the pressure regulator could be the problem?

 

[Shootinok]

Darn - I just started a similar thread, as I missed this one when I searched.
Same issue - subscribed

 

[Jswain]

do you think the pressure regulator could be the problem?

Not unless it was only supposed to be a 125psi compressor and you or someone else turned it up to 155psi. And I'm talking pressure switch not pressure regulator.

If for some reason your gauge was reading low, and someone cranked up the pressure switch setting beyond what the compressor can handle then this could happen

 

[dennisoates]

Not unless it was only supposed to be a 125psi compressor and you or someone else turned it up to 155psi. And I'm talking pressure switch not pressure regulator.

If for some reason your gauge was reading low, and someone cranked up the pressure switch setting beyond what the compressor can handle then this could happen

There is no setting for pressure

 

[Citation]

There is no setting for pressure

Typically you have a pressure switch that is adjustable but not something you would accidentally change. However, if the pressure switch is going bad that could explain a compressor running too high. However, if this is a 155 psi compressor cutting out at 155 psi, well that doesn't seem like an issue.

 

[dennisoates]

Typically you have a pressure switch that is adjustable but not something you would accidentally change. However, if the pressure switch is going bad that could explain a compressor running too high. However, if this is a 155 psi compressor cutting out at 155 psi, well that doesn't seem like an issue.

It pops before 155, at 145

 

[SteveH-CO]

Is this compressor rated to pump up to 155? Is it a 2-stage compressor? I would simply dial back the shutoff pressure to 125-130 and if that keeps it from popping the breaker, run it in that pressure range.

 

[Citation]

Is this compressor rated to pump up to 155? Is it a 2-stage compressor? I would simply dial back the shutoff pressure to 125-130 and if that keeps it from popping the breaker, run it in that pressure range.

If the compressor is tripping/having issues while operating in it's factory range I would not just dial it down and ignore the problem. Something is wrong, fix it before the problem gets bigger.

 

[dennisoates]

Is this compressor rated to pump up to 155? Is it a 2-stage compressor? I would simply dial back the shutoff pressure to 125-130 and if that keeps it from popping the breaker, run it in that pressure range.

Not adjusable

 

[Stedlin]

My two year old Porter Cable 2 hp motor is having a problem. As the compressor reaches max shutoff pressure of 155 lbs it pop the breaker. I see sparks on end of motor near brushes. It runs fine until it gets close to max pressure. I have new capacitors on it. what causes this breaker to pop? I have also tried other outlets.
thanks

How can it have brushes if it has capacitors? If it has brushes than it must be DC. If it has caps than it must be AC.

 

[tak1313]

Perhaps it's the switch. When the pressure gets to 145, the diaphragm is deforming enough to start pushing against the cut-off mechanism. Not enough to completely separate the contacts, but enough to cause a slight gap, such that the electricity erratically arcs across it. It may not be enough to see/hear/smell the arcing, but it's enough to draw enough extra current (to arc) to trigger the circuit breaker.

Perhaps take the switch apart and clean the contacts, or get a new switch?

 

[Citation]

Can we get some pictures or a model number

 

[Shootinok]

Perhaps it's the switch. When the pressure gets to 145, the diaphragm is deforming enough to start pushing against the cut-off mechanism. Not enough to completely separate the contacts, but enough to cause a slight gap, such that the electricity erratically arcs across it. It may not be enough to see/hear/smell the arcing, but it's enough to draw enough extra current (to arc) to trigger the circuit breaker.

Perhaps take the switch apart and clean the contacts, or get a new switch?

This turned out to be my problem - Thanks!!

I went through the usual steps first, replaced both capacitors, then the unloader valve. It turned out to be just what tak1313 described.

Best of luck OP, this thread was helpful!