S
Sparks Fergusson
Is that ther right Part #? Does it have some dashes inbetween the
numbers and letter like most Ge motors do?
No dashes. That's what's printed on the motor nameplate.
Is it wired for 120?
Yes.
Is that ther right Part #? Does it have some dashes inbetween the
numbers and letter like most Ge motors do?
Is it wired for 120?
The voltage to the motor is never interrupted during the stop/start
cycle. Above a certain psi (about 95), the motor starts bogging down
and eventually stops. This occurs even if I bypass the pressure switch
and attach the cord directly to the motor leads. Then, after the
unloader vents the pressure, the motor will restart.
David said:The problem turned out to be that wasps had plugged up the air input
holes with mud. Cleaned out the mud and away she went
...
The voltage to the motor is never interrupted during the stop/start
cycle. Above a certain psi (about 95), the motor starts bogging down
and eventually stops. This occurs even if I bypass the pressure switch
and attach the cord directly to the motor leads. Then, after the
unloader vents the pressure, the motor will restart.
After reading all the posts, several things stand out. The mostI'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!
On Thu, 04 Mar 2010 05:13:31 GMT, [email protected]
(Sparks
Fergusson) wrote:
After reading all the posts, several things stand out.
The most
significant: There is no excessive current draw when the
motor stalls.
By all the laws of physics, that is flat out impossible.
There are
two explanations (well, three, but I'm assuming you aren't
making this
up). The first is slippage at the belt, motor pulley, or
rotor.
Given the knowledge you have exhibited, I say that can't
be the
problem; it's pretty hard to miss the fact that the motor
is spinning
but the belt is slipping.
That leads to only one conclusion: The actual voltage to
the windings
is dropping. Possible causes are a bad thernal overload
protector,
bad run capacitor (some motors hide the starting capacitor
inside,
while the run capacitor is in a cupola on the side), or a
corroded
terminal so only one of the paired windings is used.
All of these possible causes result in a lot of heat
generated at
one small point EXCEPT the single winding and the bad run
capacitor.
The single winding explanation is unlikely because it
would not
deteriorate gradually. That leaves the bad run capacitor.
PlainBill
There is one more possible cause: Some or all of the
windings on the rotor that are supposed to be shorted are
open. An induction motor works because windings on the rotor
are shorted to induce the field needed to turn the rotor.
David
I've never seen that, but it is definitely a possibility and wouldThere is one more possible cause: Some or all of the
windings on the rotor that are supposed to be shorted are
open. An induction motor works because windings on the rotor
are shorted to induce the field needed to turn the rotor.
David
I've never seen that, but it is definitely a possibility
and would
also explain the symtoms.
PlainBill
I've never seen that, but it is definitely a possibility and would
also explain the symtoms.
PlainBill
With all the talk, I would have liked to hear the final answer to
the story. Is the compressor working yet. Its
been a long time.
Um...can I phone a friend?
Ok, here's the status. I have disassembled the motor. I have found the
following:
* The windings appear to all be in good shape. I don't see anything
obviously open or burned.
* The bearing surfaces are all in good shape.
* The contacts of the centrifugal switch are badly carbonized. I will
clean those up before reassembly.
* I have ordered a replacement start capacitor. I don't have a
capacitor tester, but for $5, why not just replace it, eh?
* The thermal overload tests OK (dead short,) but I can't easily test
it under load.
* The rotor showed no evidence of hitting the stator and appeared
undamaged.
I will clean all the connections before reassembly, although all
looked fairly good already. I'll also measure to make sure I have good
continuity through all the windings. Hopefully, that should get things
going again. Thanks to everyone for their help and suggestions.
I'll post another update when I get it all back together.
Thanks!
Wild_Bill said:The main problem is that the motor is being overloaded. As mentioned
already, induction motors don't get tired or exhibit lower power output with
age.
William said:Am I missing something?