I am an electrician that has done electrical work for an automobile repair shop this winter.
They have a large air compressor that blows the capacitors often. I replaced them once while there and they have (blown again) since then.
I believe they may have voltage drop problems not sure.
by: Doug in s.d.ca
I’m not gonna say it’s impossible, but I suppose low voltage could be a problem. More likely, I think, would be high voltage spikes taking out the caps.
Were the replacements as spec’d for the motor, or did you replace with what was on it?
Also unclear: is one or two caps you replaced?
Thanks for input Doug.
The motor has more than one capacitor but only replaced one at a time. I am not sure how many it has two maybe three.
Also I just replaced with the ones that they said went with this motor. I should check again to make sure. I was wiring an addition at the place and didn’t spend a lot of time on this problem. However I would like to fix it for them.
I know how you feel – Is this 3-phase?
Keep us posted please.
No the air compressor is single phase. The building is served with a single phase 120/240 service. However they do have what looks to me a rotary phase converter made with a three phase motor and capacitors.
When you mentioned voltage spike this set up came to mind. It is running a lathe and tumbler that cleans discs for automatic transmissions.
A motor-generator for three phase?
That shouldn’t be a problem unless it’s really squirrelly and feeds back to single phase somehow.
I finally got to the air compressor. They had tripped the breaker because the wire vibrated off the capacitor.
I replaced all the ends on the wiring of the capacitor box. They must vibrate lose then get hot and the temperature changes the strength of the stab on crimps.
I am guessing this was the whole problem. The motor was also poorly grounded.
I talked with a motor guy who has worked on it and supplied the capacitors he said they should be correct. The motor is a GE and could not find the nameplate. When I left it was running fine.
Sounds like something could/should be done about the vibration –
Maybe secure the wires to the box such that they don’t move at the connector, and/or maybe solder ’em on.
Visit our Air Compressor Capacitor Guide for more information on capacitors.
New comment? New question? Please add it here along with photos to help others help you with your compressor and equipment problem!