Air Compressor Problem - Motor Stalls
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From: Sparks Fergusson on 5 Mar 2010 19:44 Meat Plow wrote: >What kind of motor is this? I didn't see you mention that. A 1/3 horse >induction motor should not draw 1.5 amps with no load. It's some sort of GE induction motor. I have the model number, but I can't find anything about it on the GE website or Google. What sort of problems would high no-load amp draw suggest?
From: Sparks Fergusson on 5 Mar 2010 19:47 "William R. Walsh" <newsgroups1(a)idontwantjunqueemail.walshcomptech.com> wrote: >Hi! > >You should check the pressure switch contacts to be sure they aren't >burned. If they look OK, check the wiring leading to the compressor. >Perhaps something is wrong there. (Be sure you shut the power off FIRST >or you could have a shocking experience.) Pressure switch contacts look OK, and there's minimal voltage drop across under load. Wiring looks OK, too. >Failing all of that, I'd check to see if the motor uses a run capacitor. >If it does, the capacitor is probably bad. There is a capacitor, but I'm not sure exactly what it does. I don't have a wiring diagram and can't find any info on the Manufacturer's website (GE.) I'll try to check the capacitor as best I can. Could a capacitor issue cause the motor to start fine, but not have enough power when running?
From: Jamie on 5 Mar 2010 20:59 Sparks Fergusson wrote: > Meat Plow wrote: > > >>What kind of motor is this? I didn't see you mention that. A 1/3 horse >>induction motor should not draw 1.5 amps with no load. > > > It's some sort of GE induction motor. I have the model number, but I > can't find anything about it on the GE website or Google. > > What sort of problems would high no-load amp draw suggest? Bad bearings.. and if it's a single phase motor.. check the starter cap, if it has one. most likely not much good any more.. Also, you may have a centrifugal switch in the motor that isn't closing its contacts. Or, you could have an open winding!..
From: William R. Walsh on 6 Mar 2010 02:29 Hi! > Pressure switch contacts look OK, and there's minimal voltage drop > across under load. Wiring looks OK, too. Good to know. It never hurts to rule out anything particularly obvious. It also would not hurt to check the wiring connections in the motor--are they rusty, burned, loose or just bad? If the motor has a built in circuit breaker, is it good? (A bad one could have burned contacts or start to open up just enough when the load increases.) > Could a capacitor issue cause the motor to start fine, but not have > enough power when running? If it's a "run" capacitor, yes. Starting is the hardest time for a motor, and some of the air compressor motors I've seen have a dedicated start winding (and cap) to give them a little more "kick" to get going. That winding won't stand continuous operation, so it's taken out of circuit by a centrifugal switch when the motor reaches a certain speed. From that point the motor runs on a different set of windings. Since it sounds like the motor runs fine up to a point where the load increases, my money would be on a run capacitor or wiring/current delivery issue. The run capacitor would serve to give the motor a little more kick when the load increases against it. Capacitors for electric motors are usually pretty cheap. I had a furnace fan motor that would not start reliably and paid $7 and change for a new one. It made all the difference in the world. They're certainly cheaper than replacing a burned out motor. William
From: Alan Douglas on 6 Mar 2010 09:09
>>Assuming it's a 120V/240V motor connected for 120, can you check to >>see if both run windings are actually connected? Perhaps a nut is >>working loose on the terminal plate inside the motor. > >Hmm, you might have something, there! This motor is probably 15+ years >old, and has never had anything done to it. Could corrosion and/or >loose connections account for the lack of power? I can certainly try >cleaning and tightening anything I can get to. None of the other suggestions I've read, fit the symptoms. First would be low voltage to the motor under load, but you've already checked that. The starting capacitor is out of the circuit when the motor is up to speed. There's nothing left in circuit but the two run windings, wired in parallel. Alan |