Delta and Wye Systems

[Alwayslearningelec]

Any have good resource(s) that teach all about delta and wye systems in depth? I’ve googled but didn’t find anything in depth . Thanks

 

[Seven-Delta-FortyOne]

Delmars Standard Textbook of Electricity.

American Electricians Handbook.

 

[wwhitney]

If videos are your thing, I've only watched a couple of this guy's, but they were pretty good. I haven't specifically watched these:

He's got some other videos on transformers as well.

Cheers, Wayne

 

[zbang]

Could even start with this- https://en.wikipedia.org/wiki/Three-phase_electric_power (it looks pretty good).

 

[electrofelon]

That is a pretty broad topic. The physical arrangement of connecting three single phase loads/sources/coils is the easy part. Are you just looking for basics or are you interested in transformers? MV distribution systems?

 

[Mr. Serious]

I was going to try to re-write the Wikipedia article on open delta systems after noticing some mistakes in it four years ago, but I never got around to it.

 

[Mr. Serious]

I mean high-leg delta. The fact is, a lot of high-leg delta systems in the US are actually open-delta (one transformer missing) because in rural areas the power company might only run two phases out there instead of three. But the article doesn't mention that at all. And I wanted to add some pictures of transformer connections for high-leg delta. I have some good pictures that I've taken in the last couple of years, examples from here in Oklahoma. But it would be a lot of trouble for me to find the pictures I took, now. They're not organized.

The only other real issue I had with it was their definition of "ghost leg." At the time, I had heard the term, but it meant something different to me than what the article says. Now I can't even remember what that difference was. I'll probably remember if I think about it for a while. But when I searched the web for definitions, I got a bunch of sites defining it the same way that Wikipedia article does, but most of them referenced the article!

 

[zbang]

Maybe if I'm feeling bored early next year, I'll give that a go.

 

[kwired]

I mean high-leg delta. The fact is, a lot of high-leg delta systems in the US are actually open-delta (one transformer missing) because in rural areas the power company might only run two phases out there instead of three. But the article doesn't mention that at all. And I wanted to add some pictures of transformer connections for high-leg delta. I have some good pictures that I've taken in the last couple of years, examples from here in Oklahoma. But it would be a lot of trouble for me to find the pictures I took, now. They're not organized.

The only other real issue I had with it was their definition of "ghost leg." At the time, I had heard the term, but it meant something different to me than what the article says. Now I can't even remember what that difference was. I'll probably remember if I think about it for a while. But when I searched the web for definitions, I got a bunch of sites defining it the same way that Wikipedia article does, but most of them referenced the article!

We get all sorts of high leg delta setups here. All depends on the situation.

Lot of motor load - very well will get a full delta with three equal sized transformers. Still nice to have a center point grounded on one phase for what limited 120 volt loads you may have instead of having a corner ground system.

Remote location and not wanting to bring all three primary lines the open delta system is very useful.

Limited load even though all three primary lines are available, sometimes they still choose to use an open delta.

significant 120/240 single phase loads but also somewhat significant load on the third phase - they sometimes use a full delta but the 120/240 pot is larger than the other two pots.

Have a majority of load being motor loads? you get a little more bang for your buck with a 240 volt supply than a 208 volt supply. Lot of farm services around here are 240 volt delta and not many are 208/120. Though as farms have grown load wise there is a lot more 480 volt services than there used to be. They are typically 480/277 wye though there is little need to run anything at 277 volts. 480 volt delta systems that are around are either older existing (still a few around that are corner grounded) or they are open delta.

 

[Alwayslearningelec]

That is a pretty broad topic. The physical arrangement of connecting three single phase loads/sources/coils is the easy part. Are you just looking for basics or are you interested in transformers? MV distribution systems?

I'm interested i the basics but understanding how they work as it relates to electrical construction/installations.

 

[Alwayslearningelec]

We get all sorts of high leg delta setups here. All depends on the situation.

Lot of motor load - very well will get a full delta with three equal sized transformers. Still nice to have a center point grounded on one phase for what limited 120 volt loads you may have instead of having a corner ground system.

Remote location and not wanting to bring all three primary lines the open delta system is very useful.

Limited load even though all three primary lines are available, sometimes they still choose to use an open delta.

significant 120/240 single phase loads but also somewhat significant load on the third phase - they sometimes use a full delta but the 120/240 pot is larger than the other two pots.

Have a majority of load being motor loads? you get a little more bang for your buck with a 240 volt supply than a 208 volt supply. Lot of farm services around here are 240 volt delta and not many are 208/120. Though as farms have grown load wise there is a lot more 480 volt services than there used to be. They are typically 480/277 wye though there is little need to run anything at 277 volts. 480 volt delta systems that are around are either older existing (still a few around that are corner grounded) or they are open delta.

See al that makes my brain hurt.

 

[ActionDave]

I'm interested i the basics but understanding how they work as it relates to electrical construction/installations.

Other than the high leg on the delta there's not much to know and not much else to worry about. Unless you have some influence with the utility you are going to get what they give you and it's likely gonna be a wye system.

Any books or videos that have more to say than that are gonna be about the physics or the construction of electrical stuff.

 

[Hv&Lv]

we have open deltas, closed deltas, wye/wye, three pot 120/208 with 240 single phase available, all from three transformers, even a two pot 120/208. What do you want? We will probably build it.

 

[Tulsa Electrician]

StackPath

 

[LarryFine]

. . . three pot 120/208 with 240 single phase available . . .

How does that work?

 

[electrofelon]

we have open deltas, closed deltas, wye/wye, three pot 120/208 with 240 single phase available, all from three transformers, even a two pot 120/208. What do you want? We will probably build it.

That is cool. Pretty much all the POCOs I work with are all about obsolete voltages and wont give you anything interesting. Numerous times Ive wanted a 480 or 600 V single phase service for long runs so I coud just have a customer owned step down transformer instead of a step up/step down which is super annoying (If I do that I go up to MV).

 

[wwhitney]

How does that work?

Not sure if this is what Hv&Lv meant, but:

If you have a wye service made up of 3 single phase transformers, usually they all have 2-wire 120V secondaries, with one side of each secondary tied together as the common neutral point. Change one secondary to a 3-wire 120/240V secondary, and tie its mid point to the neutral side of the other two secondaries.

That gives you a phase diagram that looks like a peace symbol. The 5 wire system will have 4 ungrounded conductors. The 6 pairs of ungrounded conductors will have voltage differences of 3 @ 208V (as normal), 1 @ 240V, and 2 @ 120V.

You could also change one or two of the other transformers to a 3-wire 120/240V secondary and get a 6-wire or 7-wire system. I believe the latter is sometimes called "hexaphase" even though it only has 3 actual phases.

Cheers, Wayne

 

[GoldDigger]

Not sure if this is what Hv&Lv meant, but:

If you have a wye service made up of 3 single phase transformers, usually they all have 2-wire 120V secondaries, with one side of each secondary tied together as the common neutral point. Change one secondary to a 3-wire 120/240V secondary, and tie its mid point to the neutral side of the other two secondaries.

That gives you a phase diagram that looks like a peace symbol. The 5 wire system will have 4 ungrounded conductors. The 6 pairs of ungrounded conductors will have voltage differences of 3 @ 208V (as normal), 1 @ 240V, and 2 @ 120V.

You could also change one or two of the other transformers to a 3-wire 120/240V secondary and get a 6-wire or 7-wire system. I believe the latter is sometimes called "hexaphase" even though it only has 3 actual phases.

Cheers, Wayne

I think that this could also be considered a six-pulse full wave source when used with a bridge rectifier instead of the six pulse half-wave derived from a three wire system. The 12-pulse rectification typically requires a 30 degree phase shift with a delta-wye transformer.

 

[hillbilly1]

I mean high-leg delta. The fact is, a lot of high-leg delta systems in the US are actually open-delta (one transformer missing) because in rural areas the power company might only run two phases out there instead of three. But the article doesn't mention that at all. And I wanted to add some pictures of transformer connections for high-leg delta. I have some good pictures that I've taken in the last couple of years, examples from here in Oklahoma. But it would be a lot of trouble for me to find the pictures I took, now. They're not organized.

The only other real issue I had with it was their definition of "ghost leg." At the time, I had heard the term, but it meant something different to me than what the article says. Now I can't even remember what that difference was. I'll probably remember if I think about it for a while. But when I searched the web for definitions, I got a bunch of sites defining it the same way that Wikipedia article does, but most of them referenced the article!

That’s pretty much the way it is around here, usually open Deltas for convenience stores, usually three phase for the RTU’s, everything else is single phase. Full Deltas are usually in industrial parks, where the majority of the loads are three phase European equipment. The plant that I’m upgrading right now has an open delta because they had to add another line for close to a mile. Cost the owner $10,000 to have it brought in. Now I am upgrading to 480 three phase, they are charging him another $14,000 to bring in the third phase through the park.

 

[Hv&Lv]

How does that work?