3 wire control for air compressor 3

[crwilson01]

Hi, I am new to the forum and looking for some help with an air compressor control problem. I am trying to design a 3 wire stop start control station that will work with a single phase 240v starter.The problem lies with trying to maintain the coil circuit on the starter. I am using 3 wire start stop control to engage and seal the circuit which also runs through the pressure switch. Everytime the pressure switch opens, I loose the seal for the circuit and have to push the start button to start the compressor again. I can solve this by replacing the start stop with a simple toggle switch. Is it possible to use the 3 wire control without having to restart every time the pressure switch opens?
Thanks,
Chris

 

[davidbeach]

The whole point of the three wire control is that if something causes the motor to stop you have to manually restart it.

 

[crwilson01]

Thanks, I know, it was designed for the safety of the operator to prevent restarts of equipment once power is restored. The only reason I am trying to make this work, is that the switch I am using has some sentimental value. I know that sounds goofy but its like my grandfathers hammer that is proudly displayed in my shop.

 

[davidbeach]

Is that anything like grandfather's hammer that's had the head replaced twice and the handle three times since grandfather had it, but it's still "grandfather's hammer"? ;-)

 

[crwilson01]

That's funny. Yeah, he probably was about to throw that hammer away right before he died.

 

[waross]

Use the three wire control for a control relay. Then use two wire control from the relay through the pressure switch to the compressor.
You will be able to start the compressor when you are working in the shop and it will cycle on the pressure switch. When you are through in the shop you can stop the compressor. I hope that will maintain the sentimental attachment.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[jraef]

Or, in place of your toggle switch use a manual motor starter that has what is called an Under Voltage Release. It will open the switch automatically if there is a power loss, but will otherwise remain closed until you manually open it.

"Will work for (the memory of) salami"

 

[rhatcher]

Waross has provided the correct (lps) answer. This is the way that the pressure switch should be connected in the circuit.

 

[crwilson01]

I already have a mag starter for the motor. I think any solution to make this work is going to overcomplicate the switching process. I think my start stop switch will find a home on my drill press instead. Thanks for all the advice.