Compressor wiring

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I bought a Magnetic switch for my compressor and the schematic that came with it does not show the pressure switch. Anybody have any ideas, please see attachment.

Mickey

 

[Aceman]

Anybody have any ideas.

Hmm, I wonder if I searched for "pressure switch" or "compressor starter wiring" if anything would come up? Perhaps this question has been asked before....?

 

[straightup]

It looks like you've got a 240 single phase compressor? What brand starter is it? It looks like an IEC listed type, versus NEMA. I can't remember the terminal designations for IEC on the top of my head.

I'll try and help to explain what needs to happen. The pressure switch needs to cut out power to the coil of the magnetic starter. If the coil voltage is 240v, you can break either leg of the 240 before it reaches the coil. I would do it at the beginning of the control circuit, before the on/off or overloads.

*There are two wires on L1/Terminal # 1. The feeder wire needs to stay there. There's an additional wire shown that goes to the OFF switch. That wire needs to go to the pressure switch first, then it returns to the OFF switch. The pressure switch will be in series with L1/Terminal#1 and the OFF switch. If the ON/OFF switch doesn't have voltage, the motor won't run. The pressure switch will allow voltage through when pressure is low.

 

[jays440]

I have the same starter and did not know where to wire in the pressure switch. After reading the last post I hooked it up that way. Compressor starts and runs untill it gets up to desired pressure. once the pressure drops the compressor will not kick back on by itself. If you push the start button it will start again. Help would be greatly appreciated. Thank you, (the top wiring diagram in the original post is what I have)

 

[mm08822]

The posted wiring diagram is for 3-wire control - stop button and start button with low voltage drop-out protection. You need two wire control where PS closes below ~90 PSI and opens at or above 120 PSI. (Actual set points need to be determined for your unit.) Leave wiring from L3 to A1 as is - overload relay is between these two points (can't read contact #'s). Remove all wires connected to stop/start station. Run wire from L1 to one side of PS and another from other side of PS to A2.

 

[jays440]

Thanks for the reply. so no way to use the on/off button? I've seen the model without an on/off button wired the way you said I was just hoping to be able to use the button to turn on and off if needed. Thank you

 

[mm08822]

jay, If you want an on/off control as well, let the PS control the compressor between setpoints and then add a toggle switch in series with the PS. Some PS come with a switch lever that do the same as you want all in one unit. If you already have a good PS wired in, just add the toggle switch. This switch needs to be rated for 240 volts and can be rated for low current as it is only interrupting coil circuit - not motor circuit.

 

[jays440]

Thanks, I was going to buy the starter without the switch as my compressor originaly came without one just thought it would be nice to have an on/off. I'll take your idea about a toggle. Thanks again for the speedy response