Remote compressor run/stop switch

Winegrower

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A friend GAVE me an Ingersoll Rand T30 air compressor, so I installed it outside of the shop, with a local disconnect box and another box for the magnetic starter. There is a small leak that causes it to cycle once a day or so, and one day I'll take the time to track this down...but for now I've been shutting it off when I'm not in the shop, or on the phone, or just not in the mood. This involves going outside, ducking under a shed roof, and reaching back (in the dark :) ) to throw the disconnect switch, then reverse steps the next day to turn it on.

So I built a very simple remote control system to allow me to turn the compressor either "OFF", or to "RUN", where like normal, it will manage itself based on air pressure. With winter and hopefully some rains coming, this seems like a good idea.

To do that, I just added a low voltage relay to interrupt the pressure switch input to the mag starter. The pressure switch is a normally closed switch that opens when the pressure reaches the upper limit. If the pressure switch line is open, the compressor thinks it's full and will stay off until you remotely switch the low voltage coil back to "RUN", whence it operates normally. I set it up so the un-energized state of the relay opens the pressure switch line (STOP). stopping the compressor, and the energized state (RUN) actively connects. It's low voltage of course so I can run long wires to the switch without hazard.

There is a 220VAC to 12VDC power supply, a relay with a 12VDC coil and contacts that are rated at 250VAC at 10 amps. What makes this interesting is the low cost of all the parts. The power supply is, get this, $3.85 post paid from China, the relay is about the same, but the DIN relay socket is also about that much, and the OFF/RUN switch is about the same. So maybe $16 for parts.

The pressure switch lines are brought out of the mag starter box to the main disconnect box, where the power supply, relay and socket are located. The remote switch controls the relay coil current.

Here are some shots of the components. If anybody is interested, I can show a simple wiring diagram of this.
Relay.PNGPower supply.jpgStop switch.jpg
 
Great idea! I might just steal this one. My compressor is located upstairs and having a switch like this at the shop door would be helpful.
 
To go one step further, I went wireless.

My particular need was to turn on the engine heaters on our tractors in the winter so we could plow snow. The tractors are located in a barn 250' from the house and shoveling a path to the barn so I can plug in the tractors so I can move snow two hours later doesn't make a lot of sense.

Our local DIY had a special on a remote that was virtually free after a rebate. It came with three remote relays and a controller. It was intended for indoor use which wasn't a problem but its range was limited to 50'. I opened up the relay and connected a pin jack connector to provide external axcess to the antenna. I plugged a 20' wire into the jack and strung it up along the sill beam. To verify that the relay has been activated, I added an LED bulb which sits in the barn window.

Now I can sit in the warmth of my dining room with a cup of coffee and start my tractors warming.
Here is the model that I used.
https://www.amazon.com/Smart-Electrician-Outlets-Wireless-wireless/dp/B079MGKZKJ
 
That's really good, RJ. But I don't have a tractor and certainly don't have any snow. :) The coffee, sure.

Once you realize that you can control a 5 HP compressor, or similar device, with only switching about 60 mA of current, the world opens up a bit, no?
 
I don't agree with your setup and would not be acceptable in the industrial environment .
Looking inside the control panel you will find this machine designed with the ability to "remotely operate"
Selecting a circuit might get the job done but is not the correct way.
 
Sdelivery, you’re welcome to explain more about how the machine is designed to operate remotely.

There is no control panel, for example.
 
Posting the circuit for your compressor would be helpful. You mentioned 220 volts for the power supply so I would assume the compressor is 220 also? Does the pressure cutout switch control the motor directly or does it control a contactor? The only problem that I could see with switching the motor directly would be if only one side of the 220 line would be switch and the other side would remain live which could potentially be a safety issue. If a contactor is used, I personally would have no issue with your setup.
 
The only real concern I would have with such an installation is that the wiring should be power line rated. I noticed in the photo where a cable entered the control station looked to be thermostat wire. While this would work, it would be "jack legged" to a real electrician. Opening the circuit remotely to the contactor coil is considered acceptable in most industrial environments. Albeit with the wiring properly installed. For a "stand alone" compressor, opening the pressure switch serves this purpose. Were I to make such a modification, I would put THHN wire in EMT conduit at least to a point near the compressor with "flex" to the machine. But that's just the way I do things. . .

It would be possible to "reroute" the power line to a remote switch. Such would probably involve an extension cord and using a breaker as a switch, which would be a long term problem in itself. A circuit breaker "degrades" every time it is used and over time would become unreliable. And extension cords are temporary expedients at best and should never be used as a permanant fix.

Beyond using a "flimsey" wire to control the circuit, needing at least 300 Volt rated wire, I admire the solution. My compressor is accessable so there was no need for remote control.

.
 
My explanation was minimal. Thanks for your comments, and to respond:

The compressor is 230 Volts.
The pressure cutout switch is wired through the magnetic starter, and as manufactured and installed by Ingersoll, only switches 60 mA, but at 230V. (That's why this little relay circuit works). The unmodified magnetic starter does the rest.
The control lines to the remote switch are at 12V, that's why the 230V to 12V power supply. No need for power wires. Flimsey is OK. :)
This approach does not switch high voltage or run 230V lines through the shop. It only works exactly as the compressor is designed to do.

Hope this addresses...

Curt
 
We did something similar.

Ours also has mag starter.

First added toggle switch to face that brakes the circuit between pressure switch and starter.

Next added relay with 120 VAC coil with simple power cord.

Relay closes to connect the pressure switch to starter.

Added an outlet next to compressor wired to light switch.

Circuit is this.

Pressure switch to relay contacts.

Relay to toggle.

Toggle to starter.

Toggle is master .

Lights off relay opens compressor stops.



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