Autotransformer rewire to make it work as a normal 3ph AC transformer.

Added: 2026-05-30

[00:00:00]Tele company Douglas production and Switzana production movie after a transformer rev. Okay. So, this is how you take an auto transformer, which normally has a one wire that goes through all three phases, and then it gets uh taps off of this one wire sort of. And so, these three wires, there'll be three wires that connect all three together. So, clip those.

[00:00:42]We cut the Y connecting wire into three parts.

[00:00:47]And now you'll have three wires coming out of each phase.

[00:00:54]The two main wires will be 2.4 ohms.

[00:01:00]But if you connect this uh like this, this is see here's the two main wires here and then here's that uh auto transformer single wire that goes through all phases. So this you you connect this to one of these. Choose which one. And now you'll have 4.6 ohms in that uh phase. And you'll have 0.58 Henry's.

[00:01:33]And it'll be the same over here. They're all the same ohms. 4.6 4.6.

[00:01:40]The middle middle phase is 77 Henry's.

[00:01:46]And this one's 59.

[00:01:51]So that's what it comes out to be. So now you can play with a a uh three-phase transformer and you can do that where the middle phase is null and it has a big cap like Tim had a 92 UF and then he had a 20.75 across the secondary output to the load of a heater and then this would be the AC input.

[00:02:21]And uh so there you go. This is how you get an auto transformer to work. 4.6 ohms at 120 volt input. It's going to get pretty hot. So I'm probably going to cut the uh voltage down.

[00:02:40]Probably with a series uh AC cap as a way to uh lower the voltage. Or I could use a variac or put a transformer there. But I know that 4.6 ohms with 120 volts going into it, it's going to it's going to be getting hot.

[00:03:04]So just a minute.

[00:03:14]Thank you for watching.

[00:03:21]Thank you very much.