Controlling a compressor with Linuxcnc.

I have a serious problem with our power company. 
The 60 amps connection to our house is not what they say. I have serious voltage drops between utilities transformer and our house and they will not fix it. Looks like common practice in our area. 

I can reliably cut at 35 amps. 
if I go higher depending how much power my neighbors are using The plasma cutter gets an undervoltage and cuts out. 

So the table happily cuts until the compressor starts. 
Then the plasma cuts out because it gets an undervoltage.  Qtplasmac pauses and gives an arc lost warning. 

If the torch is off during the probing and the compressor kicks in the program keeps running until the compressor cuts out because of undervoltage.

So I can not run plasma and compressor at the same time. 

So I was wandering If I add a relay an electric unloaded valve and a pressure sensor to the compressor. Would it be possible to control the compressor with Linuxcnc.

I was thinking about the following. When pressure drops to a certain level. Well above what the plasma needs the program pauses. Preferably at the end of a cut.
then the compressor starts. When the tank is full the program resumes. 

Is that possible?

i use this sensor to check the compressor pressure,
but you need an analog input for that:

www.amazon.de/gp/product/B07YKZ773Z

Thank you so much 
You come faster than I could work out a concept. 
I do not fully understand the code.

does it stop at the end of a cycle?

Is there any code to start the compressor?

I was thinking of a simple way to use the original pressure switch on the compressor. 

I could add two Relais on the compressor. 
one with a 24V coil in series with the pressure switch.
one with a 220 V coil that closes when the pressure switch wants to start the compressor. 

So when the pressure drops the 220V relay is activated and sends a signal to Linuxcnc. 
linuxcnc pauses the program. And turns on the second relay. To start the compressor. 

Is full the The 220v relay gets turned off by the pressure switch. 

linuxcnc turns off relay2 and resumes cutting. 

The only question is will the Relay with the 220Volt coil turn off when the voltage drops during compressor startup?

 

I just gave it a second thought.
a relay with a 220 volt coil on the compressor is a bit risky. 
If your business grows and you employ people an uninformed person could connect 220  volt on the wrong wire and then probably blow the mesa board.

i think I will go with the pressure sensor. 
So far all the analog inputs of the mesa board are free. Advantage I have full control of hysteresis of the compressor as well. Disadvantage I need to put an electric unloaded valve. I guess any normally open pneumatic valve will do.

Thanks for all your efforts.
I am going to order an unloader valve and pressure sensor. 

no hurry with the software side it will take time for me to get all the parts. 

looks like LinuxCnc is really awesome.