what is thin on my air compressor

[knied1]

I was given a 480V three phase compressor, I am in the process of replacing the motor with a single phase one.
I have a doner compressor that I took the motor starter off of, and I re-built the motor.
the compressor is a 80 gallon with 7.5 HP pump.

I do not know what this thing is. It is next to the pump, and has copper tube run to the pump, and 2 wires to the motor starter.

Thanks for any help.

 

[Skin]

unloader. Dumps the pressure in the head for easy start-up.

 

[knied1]

thanks

where do I wire it to?
I do not see where on the single phase motor starter for it?

or can I just leave the electrical part of it disconnected?

 

[Skin]

They generally get wired to the switch so that when the pressure switch triggers the solenoid opens releasing the head pressure.

 

[knied1]

So I can wire it to the same terminals as the pressure switch?

 

[Skin]

That I don't know. Might be voltage specific. See if there is any indication on the switch or harness. They're normally closed so you can try powering it up and listing for the solenoid to open. I wouldn't leave it off since its going to dramatically increase the start-up load on the motor but its also a simple enough part to replace if needed.

 

[kams1973]

Reminds me of a low oil switch on a Champion pump

Need better pics

 

[knied1]

I looked online, at pictures and kams1973 your correct.... it is a low oil level switch.

The single phase magnetic starter that I'm using doesn't seem to have a place to wire it.
is there a place I can wire it to?

Thanks

 

[kams1973]

If it's a normally closed switch, seems like you can wire it in series with the psi switch if the voltage & amperage rating is adequate

 

[md21722]

Generally you would just wire it in series with the pressure switch.

 

[knied1]

You guys are great.


THNAKS for all of your help.

 

[knied1]

OK so ive been running the air compressor off of an extension cord.
Now I want to just wire it up to its own breaker.
I amusing a 30 amp 220V breaker.
and am planning to run 10-2 romex.

anyone see an issue with this?
the run will go from the breaker panel straight up about 7 feet, 30 feet across the barn truss, and then down approximate 12 feet to the compressor.

I know a lot of people prefer THHN, but im just looking to avoid dealing with the conduit.

Thanks again guys.

 

[redmondjp]

For a 7.5HP motor and that length of circuit run, I'd go with 8/2 NM-B cable, which is $1.49/foot at Home Depot.

 

[md21722]

OK so ive been running the air compressor off of an extension cord.
Now I want to just wire it up to its own breaker.
I amusing a 30 amp 220V breaker.
and am planning to run 10-2 romex.

anyone see an issue with this?
the run will go from the breaker panel straight up about 7 feet, 30 feet across the barn truss, and then down approximate 12 feet to the compressor.

I know a lot of people prefer THHN, but im just looking to avoid dealing with the conduit.

Thanks again guys.

Definitely do not use #10 or a 30A breaker!

For a 7.5HP motor, by code you need #8 THHN (in conduit) or #6 NM-b (Romex). Breaker should be at least 40A but can be as large as 100A to prevent nuisance tripping.

 

[knied1]

THanks again for the fast responses........guess ill just have to not be lazy and run the conduit.

 

[md21722]

You can use flexible conduit with stranded THHN.

Not sure why you don't want to use the Romex.