3 phase question

[Fritz Maurer]

Here's what's coming out of the transformer, and a pic of the switch controlling the spreader motor.

 

[MarkB_MI]

Im still gathering info to present here, but just want to quickly clarify that the 24V transformers failed at another location, where I had a 3 phase generator inside the garage at the time I made the emergency hookup and cooked the transformers.

I was not hooked to the transformer in question.

Here is the crusty remains of the schematic of the generator I used to fry the transformers. As I recall, the doors worked one cycle, so the transformers didn't fry right away... but they didn't work in the morning when the power came back on View attachment 135191

It looks like it's a wye-wound alternator, but its neutral isn't available at the output lugs. Tying the the generator into your house without a neutral doomed those transformers. You're lucky you didn't toast anything expensive.

 

[used red MN]

Here's what's coming out of the transformer, and a pic of the switch controlling the spreader motor. View attachment 135206View attachment 135207View attachment 135208

To be clear you said this in reply 9
“I am currently in the middle of a meter setting re-do, a(nd) the transformer is currently disconnected so I can obtain no voltages at this time.”..
Questions:
The transformer shown is the one that has been connected to this bin site but is temporarily out of service while the meter circuits it feeds is being redone? Meaning you have no access to the inside of the transformer box unless granted to you by the power company. This I suspect will only be allowed while one of there employees is on site and knows the power is off to the transformer.
All correct?
Do you expect or is it required that your 3 phase connections to the garage are up to par with the NEC?
I suspect you know that without a diagram showing where they connect to the transformer or physically seeing it only a genie could tell you what voltage and phase the wires laid over your barrel will have if the transformer feed is disconnected.
Edit: Per a conversation on here about your shop wood stove and insurance I will retract my code compliance question. I think I know the answer.

 

[Fritz Maurer]

It looks like it's a wye-wound alternator, but its neutral isn't available at the output lugs. Tying the the generator into your house without a neutral doomed those transformers. You're lucky you didn't toast anything expensive.

How did the 120 v garage door openers work? They had the same neutral as the transformers, all going to the same terminal bar, and eventually to the ground rod.

The 220V air compressor started as well, ran up and shut off, never had any trouble with that at all . That had a magnetic starter, don't know how that compares with a transformer in terms of voltage.

 

[MarkB_MI]

How did the 120 v garage door openers work? They had the same neutral as the transformers, all going to the same terminal bar, and eventually to the ground rod.

The 220V air compressor started as well, ran up and shut off, never had any trouble with that at all . That had a magnetic starter, don't know how that compares with a transformer in terms of voltage.

The garage door openers had an alternate current path through the devices on the other leg, such as the unfortunate 24V transformers.

Your 240V compressor doesn't need a neutral.

 

[buickanddeere]

usually the square root of 3 , hence . 120/208, 277/480, 347/600. the high leg, low leg is weird US stuff. Use a three phase motor instead of single phase motor.

 

[kencombs]

Here's what's coming out of the transformer, and a pic of the switch controlling the spreader motor. View attachment 135206View attachment 135207View attachment 135208

Wires in the first pic are most likely from 240v 3ph high leg delta system. One reduced size conductor taped white to
indicate neutral, 3 conductors the same size, one marked red or orange to indicated high leg, nominal voltage would be 208v.

I have such in my workshop. Since the local city utility runs a little hot, mine is normally 214/218.

Ideal for a small shop as it provides 240V single phase from the two 120v legs, 120v single phase from either of those two and neutral, 240v 3phase from all three.

If that's what you have, be sure the panel has the high leg clearly marked to prevent using it as a 120v single phase source. That will surely damage anything expecting a 120v supply. DAMHIKT