Compressor magnetic motor starter

[okrobie]

Recently acquired a Curti-Toledo air compressor “as-is”. The biggest problem was a bad motor capacitor. It’s running good now, but I’m concerned about the magnetic motor starter. I don’t know what it’s supposed to do. When power is applied (using an external disconnect), the motor starts normally, but the magnetic motor starter doesn’t seem to do anything. There is a button on the front, but it doesn’t do anything when the motor is running. It seems that there used to be labels on the button but they are gone. Am I worried over nothing? Thanks, Jim

 

[RPH]

Pictures help! Motor starter is nothing more than a relay sized to the load. Button you mention most likely overloads for motor. There should be a pilot circuit that controls starter coil. So a switch of some kind opening the current applied to starter coil. Large leads on starter top should supply current to motor. How do you control it now?

 

[Walkers]

Yeah, I would love to see how it is wired.

 

[Jswain]

Pictures of how it and the pressure switch are wired will help but it is basically an on/off switch and the pressure switch tells it when to turn on and off. Button on the front is typically a reset if it overloads

 

[redmondjp]

From your description, it sounds like the motor starter is doing its job just fine - it performs two functions - it serves as a high-current relay/contactor so the motor current doesn't pass through the pressure control switch, and it also serves as the motor overload protection. The button on the front of the starter is typically a reset switch for the overload protection.

 

[okrobie]

Thank you all for your help. Looks like the button is indeed an overload reset button. I don't read any foreign languages but if I had been paying attention I would have seen the sign "RESTABLECIMIENTO" which even in my ignorance, I could have guessed that it meant "RESET"

Now I have another question. I found some buttons hidden between the pump and the motor' I will add a photo later. It looks like a test button. It'll take me a few minutes to post the photo.

 

[okrobie]

This thing looks like an overload test button but may also be an over pressure device. It has a broken 1/4” ****** sticking out but I can’t find a place where the ****** was connected. And it has a pair of wires which go into the magnetic starter and look like the would cause a connection to ground if activated.

 

[LXCam]

That looks to be an auto drain solenoid. So every “x” amount of minutes it opens up for “x” amount of seconds or fraction there of. And it was probably located at the lowest point of the tank which is why you aren’t easily seeing it.

 

[Bert_]

This thing looks like an overload test button but may also be an over pressure device. It has a broken 1/4” ****** sticking out but I can’t find a place where the ****** was connected. And it has a pair of wires which go into the magnetic starter and look like the would cause a connection to ground if activated.

Automatic drain

 

[okrobie]

Yes, I see now how that would be an automatic drain. I'll remove the broken off ****** and put a street "L" into the bottom of the tank and thread this unit into the street L' I'll let you know how it goes.

 

[Cospne]

That is indeed an electronic automatic drain possible rebranded by Midwest control for RTI. There is also a knurled fitting on the end that can be removed and within it is a stainless steel screen which protects the solinoid valve. You can clean it and reinstall it. You can also get a bell 1/2” X 1/4” and use the outside threads if you can’t get the broken ****** out. When you do reinstall it make sure the retaining nut that holds the solinoid coil is tight, the have a tendency to come loose from vibration. When all else fails a manual brass drain assemble is a good option.