Compressor motor

[Bob Vavricka]

My compressor quit (Ingersoll Rand) and I determined the start capacitor was bad, it had went bad a few years ago also, so I got a new capacitor and put it on. When I turned it on, the motor vibrated and threw the breaker. I disconnected the belt so I was only trying to start the motor. It did the same thing, but after cycling it a couple of times on and off, it started to run as it should. I think the centrifugal switch was sticking closed and broke open. Took the motor apart and the contacts on the switch were pitted and burned. I ended up using some 1000 grit sandpaper to clean them up a litte. I know they are only plated and may not last long, but for now it seems to be working OK. Planning to replace the motor if I have any more problems. I attached a pic of the motor plate and the HP is listed as SPL. Trying to calculate the motor HP form the data plate, I think it is about 3HP. Motors, seem to be all over the place in price. I found a
Leeson (https://www.surpluscenter.com/Electrical/AC-Single-Phase-Motors/AC-Motors-Base-Mount/5-HP-Special-Duty-230-Volt-AC-3450-RPM-Leeson-Air-Compressor-Motor-10-2530.axd)
at Surplus Center that says it is a 5HP, but has the same SPL on the motor plate and seems to match up otherwise with this motor. My questions, 1. Does this look like a reasonable replacement, if not what would you recommend? What HP would you say the motor I have is? I looked, but couldn't find a replacement contact plate for the centrifugal switch, are they available anywhere?
435668

[David L Morse]

I think the centrifugal switch was sticking closed and broke open.


Probably the opposite. The contacts should be closed when starting and open when up to speed.


Took the motor apart and the contacts on the switch were pitted and burned. I ended up using some 1000 grit sandpaper to clean them up a litte. I know they are only plated and may not last long,


Those contacts are subjected to an arc every time they open. The arcing causes the pitting and burning. Contacts like that are not usually plated because plating can't tolerate the arcing. Good spring tension and free movement of the weights are as much of a concern as contact surface appearance.


I looked, but couldn't find a replacement contact plate for the centrifugal switch, are they available anywhere?


A quick Google search yields this (https://www.eis-inc.com/rotating-mechanism/p-ph23-rm%20er-9). Nidec is a major motor manufacturer so replacement parts should be available. Next time you have the motor apart get some good photos of the switch. Be sure any part numbers are clearly visible. Centrifugal switches are a common replacement part.


I attached a pic of the motor plate and the HP is listed as SPL. Trying to calculate the motor HP form the data plate, I think it is about 3HP. Motors, seem to be all over the place in price. I found a Leeson (https://www.surpluscenter.com/Electrical/AC-Single-Phase-Motors/AC-Motors-Base-Mount/5-HP-Special-Duty-230-Volt-AC-3450-RPM-Leeson-Air-Compressor-Motor-10-2530.axd) at Surplus Center that says it is a 5HP, but has the same SPL on the motor plate and seems to match up otherwise with this motor. My questions, 1. Does this look like a reasonable replacement, if not what would you recommend? What HP would you say the motor I have is?


"SPL" means special. That motor was designed for use in a compressor and not as a general purpose motor. So, yes, based on the current rating you could say that it compares to a 3HP gp motor. But, it likely has a higher locked rotor torque to cope with a compressor's starting needs. It may or may not have the same lifetime as a gp motor at the same continuous load, but the compressor is not a continuous load.

The Leeson might work. US Motors should have a replacement available. Any decent motor retailer should be able to cross reference the motor.


If I were trying to avoid some down time I would probably work a bit harder on finding a replacement switch to keep on hand rather than a motor. The switch costs less and is much easier to store. Otherwise, see how long it lasts and if it fails again try cleaning the moving parts. And get some pictures.

[Bob Vavricka]

David, thanks for a detailed reply. I wasn't using the right term to search. The link you posted had what I needed, but unfortunately, they required a $500 order to use a credit card so with that info and a little searching I found a stationary switch with one set of contacts which is what I need. A little pricey at $60 but less than a replacement motor. Thanks again for taking time to respond to my post.

[Bruce Wrenn]

Contact a distributor who handles US Motors, and they could locate someone who has parts. Also google the model number. Google "US Motors model xxxxxx. "

[Bill Dufour]

I believe they make a solid state motor starter switch that has no moving parts. I think it is basically a timer that turns off after a short time. By that time the motor should be up to speed. BTW I would up the voltage on that capacitor to at least 400 volts.
Bill D.

http://catalog.torq.com/category/sinpac--solid-state-switches

[Bruce Wrenn]

I believe they make a solid state motor starter switch that has no moving parts. I think it is basically a timer that turns off after a short time. By that time the motor should be up to speed. BTW I would up the voltage on that capacitor to at least 400 volts.
Bill D.

http://catalog.torq.com/category/sinpac--solid-state-switchesIf the start switch is bad, and you can't replacement, look at replacing it with a potential relay. My Delta sander uses one, and I have a Skill bench grinder that uses a relay. Your refrigerator uses one ( most likely solid state,) many submersible pumps(three wire models.)

[Bob Vavricka]

Bruce, I've Goggled the motor model which is I/R # 56283138 numerous times and ways and most often I get a 5HP motor with a different frame type and higher FLA amps. I do have a new set of contacts coming for the centrifigal switch, so I'm good for now. Thanks.