Keith has good advice-- but be sure you're talking about real horsepower
and not "Sears" horsepower. Best to go by the amp rating on the motor
tag.
Joe
====
Keith Kaplan wrote:
>
> Do you have any evidence to suggest this compressor _should_ work on a 20
> amp breaker? I think it's reasonable for the motor to draw twice as much
> current under load as without load. How many horsepower does the motor say
> it puts out, and how old is it? Multiply hp X 750 to get watts, divide that
> by volts to get the approximate amperage, then fudge that up some since the
> motor's not 100% efficient, and you have the current the motor probably
> needs.
>
> Chances are, if the compressor can build up 90psi, it's doing fine. I think
> the most common failure mode is that the rings or valves stop sealing as
> well (just like in an engine) and the motor keeps turning but you're not
> building up more pressure. This is what I'd expect to have happen if it was
> run dry for a long time. The other possibility is that when the compressor
> piston(s) heats up, it siezes. If you let the compressor cool off for half
> an hour or so after building up 90 psi, will the motor start and build more
> pressure?
>
> If the regulator is turning off the motor too soon, that can be
> fixed/replaced pretty easily after making sure the tank, etc. are rated for
> more pressure than the regulator is letting you build up. If you're blowing
> the breaker before the regulator kicks in, the regulator's probably not your
> problem.
>
> keithka
> '61 Elva 300 FJr.
> > -----Original Message-----
> > From: Brad Young [SMTP:byoung@ti.com]
> > Sent: Monday, May 04, 1998 5:23 PM
> > To: shop-talk@Autox.Team.Net
> > Subject: air compressro
> >
> >
> > Folks, I am getting a used air compressor. FREE. However as with
> > most things there is a slight problem.
> > It shorts out a 20amp breaker after pumping up to 85-90lbs,
> > Things I know
> > 1)The controller has been replaced.
> > 2) The compressor was run low on oil at one time. a couple of years ago. I
> > am not
> > sure how long.
> > 3) I need to determine wether it is the compressor or the motor. (or is
> > there something else)
> > 4) The motor draws around 12amps with no load. I understand that this is
> > normal
> >
> >
> > Does any know of how to diagnose this problem. Any ideas would be
> > gratefully accepted.
> >
> > Thanks
> > Brad Young
> > 78 midget (mr goofy)
> >
> >
> >
> >
--
Heather & Joe Way
Sierra Specialty Automotive
Brake cylinders sleeved with brass
Delco alternator One-Wire conversions
Quincy, CA
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