Air Compressor Problem - Motor Stalls
in [Repair]
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From: GregS on 4 Mar 2010 10:04 In article <hmohsd$30o$1(a)usenet01.srv.cis.pitt.edu>, zekfrivo(a)zekfrivolous.com (GregS) wrote: >In article <4b8f3f2a.47238118(a)news.eternal-september.org>, > hatespam(a)invalid.invalid (Sparks Fergusson) wrote: >> >>I'm having a problem with my 20 gallon, single stage electric air >>compressor. It's acting like the motor is underpowered - it pumps up >>to about 95 psi ok, but then the motor stalls. The unloader bleeds the >>pressure off, the motor restarts, runs for a couple of seconds, and >>then stops again...repeat...repeat... >> >>It worked fine for years (The pressure switch would shut it down at >>about 120 psi) but over the past few months, it's gotten worse and >>worse, and now will only make about 90-95 psi before the motor stalls. >> >>I cleaned and lubricated the compressor itself, and it spins freely >>and doesn't appear to be binding or otherwise have excessive friction. >>The check valve/unloader is working and the piping is all open and >>clear. >> >>It seems like the electric motor (1/3 hp) just no longer has the oomph >>it used to. It starts up fine, no humming, no smoking, no bad smells, >>no clunks. It just doesn't seem to have enough running torque to >>handle the load like it did before. >> >>Anyone have any ideas? >> > >Check the line voltage while opperating at the motor. >I can do that stall with a long extension cord. > >greg Is it oiless ?If so, check the bearing. greg
From: Bennett Price on 4 Mar 2010 12:55 On 3/3/2010 9:13 PM, Sparks Fergusson wrote: > I'm having a problem with my 20 gallon, single stage electric air > compressor. It's acting like the motor is underpowered - it pumps up > to about 95 psi ok, but then the motor stalls. The unloader bleeds the > pressure off, the motor restarts, runs for a couple of seconds, and > then stops again...repeat...repeat... > > It worked fine for years (The pressure switch would shut it down at > about 120 psi) but over the past few months, it's gotten worse and > worse, and now will only make about 90-95 psi before the motor stalls. > > I cleaned and lubricated the compressor itself, and it spins freely > and doesn't appear to be binding or otherwise have excessive friction. > The check valve/unloader is working and the piping is all open and > clear. > > It seems like the electric motor (1/3 hp) just no longer has the oomph > it used to. It starts up fine, no humming, no smoking, no bad smells, > no clunks. It just doesn't seem to have enough running torque to > handle the load like it did before. > > Anyone have any ideas? > > Thanks! Do you know for sure that your gauge is correct? Maybe the compressor and pressure switch are fine.
From: Sparks Fergusson on 4 Mar 2010 13:09 Sansui Samari <jimjam1942(a)gmail.com> wrote: >On Mar 3, 9:13=A0pm, hates...(a)invalid.invalid (Sparks Fergusson) wrote: >I agree to check the brushes, if it's not a brushless motor. It's an AC induction motor, so no brushes. Could it be a capacitor issue? >Does the unloader bleed the entire tank off? If so, then the check valve is >probably bad. It's a combination check/unloader valve. I cleaned and lubricated it, and it appears to be working fine. The tank holds pressure - the unloader just vents the tube between the tank and the compressor. >It could also be that your shutoff set point has self >adjusted back. Good thought, but the pressure switch seems to be functioning well. I am getting around the problem by turning down the pressure below the point where the motor stalls. But, that's only about 90 psi, which is not as much as I'd like. Plus, the problem seems to be getting worse. Thanks!
From: Sparks Fergusson on 4 Mar 2010 13:14 PeterD <peter2(a)hipson.net> wrote: >On Thu, 04 Mar 2010 05:13:31 GMT, hatespam(a)invalid.invalid (Sparks >Fergusson) wrote: > >> >>I'm having a problem with my 20 gallon, single stage electric air >>compressor. ... > >Bad pressure switch. The unloader is part of the pressure switch so if >it is being activated, the pressure switch is 'saying' that the >pressure is sufficient. Maybe it is just mis-adjusted. Actually, it's a mechanical unloader (combination check valve/unloader, which I have already cleaned and lubricated.) It seems to be working well. >Check the adjusting screws, and reset the cutoff back to 120 PSI. >Confirm the cuton is at 95 PSI. The pressure swicth seems to be working fine. If I turn down the pressure adjustment, I can get the contactor to turn off the motor before it stalls, but that's only 90-95 psi or so. If I adjust it higher, the motor is unable to turn the compressor if the pressure is more than 95-100psi. It's definitely the motor stalling, not the pressure switch opening. Thanks!
From: Sparks Fergusson on 4 Mar 2010 13:16
zekfrivo(a)zekfrivolous.com (GregS) wrote: >In article <hmohsd$30o$1(a)usenet01.srv.cis.pitt.edu>, zekfrivo(a)zekfrivolous.com (GregS) wrote: >>Check the line voltage while opperating at the motor. >>I can do that stall with a long extension cord. >> >>greg > >Is it oiless ?If so, check the bearing. > >greg Line voltage is OK, about 123 volts. It drops to around 121 volts when the motor stalls. Voltage drop across the pressure switch is minimal (less than a volt.) I'm not using an extension cord. The compressor is oil filled, and has oil in it (although it is rather old oil, come to think of it.) But, I can easily turn the compressor over by hand and it feels like it's moving freely, with no excess friction or binding. Thanks! |