Sean, you are running an undersized transformer for a single phase motor on a three phase system.

Perhaps this has been contributing to your problems all along.

You are running an unbalanced load for extended periods with an undersized transformer and undersized wires.

Please bring someone in there and don't get offended at what they say/do.

https://www.aircompressorsdirect.com/Ingersoll-Rand-2340L5.230-3-Air-Compressor/p2444.html

Balance the load.

Solder those connections.

Shaun - my memory is not so good sorry. Went back to the 'why is this breaker failing me' and see you do have three phase power. I do believe the transformer connection failed, however Chris is correct:

That transformer is 1 phase. Power is 3 phase.

I called Nstar years ago and they said I have 208V single phase.

What test can I do at the inside or outside breaker box to determine? Have a Fluke of course.

looks like triple beaker, 3 buss bars, 3 wires + neutral going into pipe to your unit.

http://forums.pelicanparts.com/uploa...1504700766.JPG

Yes, that's it. It was the center top connector that I fixed. What a piece of junk this breaker box is.

I will call them again tomorrow just for fun. and take a pic of inside breaker.

So I have had the compressor plugged into the wall outlet (no transformer) for a few weeks now. Has run just fine. This morning I could hear the pump struggling a little so I shut it off immediately. Checked everything and actually determined that I hadn't changed the oil for 2.5 years when a once per year change is called for. Changed that and plugged it in and it ran fine for the most part though there were times when it start up to fill, running strong, then lose a little steam for 20 seconds, then catch it's breath and be back to normal. It wasn't so much that I was overly concerned but you could hear the change in tone of the pump during this cycle. Didn't happen all the time.

That prompted me to send an email to Eversource. Two story commercial building, I have the second floor. I asked if I had single or three phase. The engineer's response was:

There is both 1ph, 120/240V and 3ph, 240V delta going to that building. You would need to contact your electrician to find out about your breaker box or other private property equipment.

I asked if they knew which went to which floor and they said they didn't.

My floor has roof mounted HVAC to cool or heat the entire floor, about 4000 sqft. About 15 years ago I had a professional electrician disconnect that and wire in a silk screen dryer to that circuit. The dryer could be used 230V-single or 230V-3ph. The compressor outlet, shown below, was for a 5000 watt metal halide bulb used for exposing silk screens.

The industrial space below me has no major electrical requirements except for an industrial size Hot Dawg natural gas heater to heat their space.

Not sure if either of those provide clues as to what I have.

I did run these tests with a Fluke meter if that helps in determining what I have.


http://forums.pelicanparts.com/uploa...1593720878.jpg




And my friend came down with his Fluke Scopemeter that we connected to a dryer extension plugged into the compressor outlet.

http://forums.pelicanparts.com/uploa...1593721009.jpg






Any thoughts?

Three phase is easy to spot as all three wires will be 230v.
Single phase will only have one 230.

^^^ Thank you. With the transformer rewired, I got these readings. Also used a temp gun to see if any of the wires heated up with the compressor running. Several went from 84F to 91F and then cooled off quickly when the compressor stopped running. Interestingly, the two wires that burned at the connector stayed cool. Compressor running well in hot and humid conditions but the real test will be in a few hours with the air dryer running, the compressor runs just refilling after the dryer dumps out wet air.

http://forums.pelicanparts.com/uploa...1593786095.jpg

Transformer gel is measuring at 105F after 4 hours of on and off use which seems relatively cool to me. I'm considering leaving the box open with a fan blowing on the gel and wiring though think that may be a fire hazard. The heavy metal enclosed case must reduce the risk of fire.

I thought you were going to replace that entire box

Me too.

Lol

What's your amps?

I went with an American rotary transformer. Great customer service that sized it correctly for my application. And by great customer service. I literally asked the most basic questions, and the guy was very understanding and walked me through the process.

So looking back at it. Your breakers are 3ph. I would say balanced at 210v.
Which means that your single phase is ran off one leg....?
The benefits to keeping it three phase is the smaller wires gauge to the equipment.
What are you trying to do again?

Yes, I think that's it. The 210V outlet installed 10+ years years ago by a professional electrician runs off one of the legs at the breaker.

I'm running a 230V air compressor on a 210V line. I'm using the bb transformer to meet the voltage requirement. Single phase motor. Single phase line. Single phase transformer.

Why those two wires got hot I'll never know, and I don't think anyone else will either, but it's working now and will be inspecting it on a daily basis. I think I will leave it open. It allows me to temp gun it in seconds. Been at 103-5F all day, compressor running all day. Breaker is turned off at night.

transformer has been working perfectly for weeks now and I did find out why it got hot in the first place. Belt tension. Turns out the belt is loose so the first time it turns on in the morning, it spins just fine but then the belt tension makes the motor work harder. The belt does heat up and the whole thing runs fine the rest of the day but it's that first fill in the morning that does it, you can hear the belt screech about 1 minute into the tank fill and the motor starts to lug. Tensioned the belt and drained oil and put new in and it's like new.

Thanks again for all the help!