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Need help with air compressor problem

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Cast Iron
Joined
Oct 16, 2010
Location
MO, USA
I have a Ingersoll Rand 5 HP 220 V single phase air compressor and I'm having problems with the pressure switch.
The original one was fried after about a year of use. I seem to replace the switch about every year or so now, I think they should last a little longer than that.

I think that the contacts in it are not big enough for the application. I bought it brand new and always buy Ingersoll Rand replacement parts but I keep having the same issue. The contacts look very thin and weld shut and then the pressure relief kicks open.
Does anyone know of a solution to this problem.
 
I replaced the clunky pressure switch with a SMC digital pressure switch. The hysteresis is programmed with what on/off pressures I had, 125 psi on and 150 psi off.
The display has some programming choices. Like red or green or red when on and green when off. Needs 12-24v dc.

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The contacts that you are using are being switched at high voltage. You can change that to a lower voltage some way and keep what you have.
 
I just replaced mine, for a 4hp, with a SquareD for $39.

Rons, how much$$ and how big of a differential will it do? Also I don't see an unloader, does it not have one?
 
I just replaced mine, for a 4hp, with a SquareD for $39.

Rons, how much$$ and how big of a differential will it do? Also I don't see an unloader, does it not have one?

Probably as big as you want. Of course you don't see an unloader. The switch is only 1 inch on each side.
 
. . .I think they should last a little longer than that. . .

These switches have a horsepower rating. Are you getting a reliable brand, rated for your motor? You might try buying a higher-rated switch (more money) and see if things improve. Another, kludgy option is to use your pressure switch to control a heavy-duty contactor, or solid-state relay. That takes all the load off your pressure switch contacts.
 
These switches have a horsepower rating. Are you getting a reliable brand, rated for your motor? You might try buying a higher-rated switch (more money) and see if things improve. Another, kludgy option is to use your pressure switch to control a heavy-duty contactor, or solid-state relay. That takes all the load off your pressure switch contacts.

THIS . . . and not kludgy at all. Use the pressure switch to control a proper motor starter contactor and you will never have to buy another switch again.
 
These switches have a horsepower rating. Are you getting a reliable brand, rated for your motor? You might try buying a higher-rated switch (more money) and see if things improve. Another, kludgy option is to use your pressure switch to control a heavy-duty contactor, or solid-state relay. That takes all the load off your pressure switch contacts.
I did this with a float switch that controls a coolant pump. The float switches contacts couldn't handle the 1/10th hp pump, but it handles the low current to control the relay just fine.
 
These switches have a horsepower rating. Are you getting a reliable brand, rated for your motor? You might try buying a higher-rated switch (more money) and see if things improve. Another, kludgy option is to use your pressure switch to control a heavy-duty contactor, or solid-state relay. That takes all the load off your pressure switch contacts.

I am buying what IR says I'm supposed to use. I questioned them (IR) about it and their answer is always the same part number.
 
THIS . . . and not kludgy at all. Use the pressure switch to control a proper motor starter contactor and you will never have to buy another switch again.

I am not an electrician at all. Do I need to use a lower voltage to operate the pressure switch to engage the starter?
 
I am not an electrician at all. Do I need to use a lower voltage to operate the pressure switch to engage the starter?

No, make sure the coil on your new starter is same as line voltage.
You of course could use a low voltage coil but that is a little more involved by adding a small transformer.
I think the main reason low voltage is comon is so if someone pushes a defective start button they dont get a shock. Not a danger on you system, it already has line voltage at the pressure switch.
 
I would say my rule of thumb is that above 3HP a switch really needs to be more then a simple mechanical system if it will be used often. So I say add a contactor controlled by the pressure switch.
Bill D.
 
I would say my rule of thumb is that above 3HP a switch really needs to be more then a simple mechanical system if it will be used often. So I say add a contactor controlled by the pressure switch.
Bill D.

The motor spec plate indicates 21 FLA. This seems like a lot of amps to go through the very light duty looking contacts on these pressure switches.
 
IR's design is intended to keep costs down, not provide a robust solution. Might work ok for a compressor that sees occasional use, but not one that runs all day every day. Wiring a motor starter into your pressure switch is not that difficult. This example is 3 phase, but take one leg out and that what you need to wire up. It took 15 seconds to find this:

http://compressors.tpub.com/TM-5-4310-385-13/img/TM-5-4310-385-13_30_1.jpg
 
OK. But the mfg website says that particular starter style is available for 1ph 5hp @230V:
From https://elimia.ecrater.com/p/24669082/elimia-acms-55-8-230lc-air-compressor: "This is our new line of low cost - better than the competition - magnetic starters. These are available in this configuration up to 20 HP @ 480V; 10 HP @ 230V 3-phase; 5 HP @ 230V 1-phase. We have a very similar low cost set up in even larger sizes with a larger enclosure. . ."
 
OK. But the mfg website says that particular starter style is available for 1ph 5hp @230V:
From https://elimia.ecrater.com/p/24669082/elimia-acms-55-8-230lc-air-compressor: "This is our new line of low cost - better than the competition - magnetic starters. These are available in this configuration up to 20 HP @ 480V; 10 HP @ 230V 3-phase; 5 HP @ 230V 1-phase. We have a very similar low cost set up in even larger sizes with a larger enclosure. . ."

I'm getting confused here. The little contacts in the pressure switch are welding shut. If I run the 230 v through it to control the starter won't they still weld shut?

As a temporary fix. I filed the weld gobs off the contacts very carefully then sprayed them with some electrical lubricant I found and fired the thing back up. Should last for about 3 to 5 days.
 
I'm getting confused here. The little contacts in the pressure switch are welding shut. If I run the 230 v through it to control the starter won't they still weld shut?

As a temporary fix. I filed the weld gobs off the contacts very carefully then sprayed them with some electrical lubricant I found and fired the thing back up. Should last for about 3 to 5 days.

The current flowing thru those little contacts when connected to motor is HIGH, current flow thru those little contacts is LOW when connected to starter. The starter, with larger contacts then carries the HIGH current. Capiche?
 








 
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