How does the typical mains power connect in the USA anyway?

[krw]

I believe most generators in the use are Delta, where loads, as you state, are Wye. Transimisson is Delta as is most distribution, IIRC.

[krw]

Yeah, the towers would fall over.

[gfretwell]

I am not surprised. It is basically the same operation, a big 3p pump with little else but a starter.

[Doug Miller]

[e-mail] wrote in news: [e-mail]:

with

Wrong again. Triplex cable (see link above) isn't used for distribution anywhere in the U.S. that I'm aware of -- it is, however, very commonly used for service drops (from the transformer to the customer's service mast).

Like I said... don't you think it's time you stopped assuming that what is true in your obviously limited experience is true everywhere?

[krw]

Entering the house (on the PowerCo's side of the meter), it often is bare. There isn't much reason to insulate it since it's tied to ground at both ends (and is out of reach in the rare case of a fault).

[krw]

Correct.

Sure, that's why you have a neutral, to carry the difference in the current of the two legs. That's why it has to be the same gauge as the hots, unless it's a certain size (where cancellation can be assured).

Sure. So? That's what the neutral is for. Add to this, the harmonic content from your switching power supplies and fluroescent lights. It gets ugly.

Sure. There *is* current in the neutral. That's the reason it's there.

What's the resistance of the wire?

The resistance of the wire.

[TimR]

After bud's excellent explanation, we can see that Danny is almost right.

The ground IS a parallel path for return, but most of the current will flow along the neutral wire.

If there's not a neutral wire, then..........no don't go there. Yet.

Back to that single phase feeding the house from the transformer secondary for a second.

The center tap of that transformer is bonded to ground. That gives us a ze ro reference. But that technically is not necessary. Your house would wor k fine without it. Your oven would still "see" 240 volts and your lights 1

1. The problem is you might have a voltage difference between some of you r equipment and ground.

But transformers are not limited to one tap. This secondary could easily b e tapped at 60, 120, 180 and 240 volts referenced from tap to "low" termina l.

Do I now have 4-phase power? Do I have four legs out of phase?

[gfretwell]

At a certain point we have to stop all of the "phase" BS and just say this is single phase. Anything else is just wrong. Split phase refers to the way some motors are wound and two phase is something else altogether (4 wires with 2 phases 90 degrees out) Standard 120/240v service is single phase that just happens to be grounded on the center tap.

[Michael A. Terrell]

Idiot. Read this:

[nestork]

I dunno.

I'm glad that this discussion hasn't turned into an insult hurling contest as so often happens.

I think Danny now has a much better idea of how his electrical panel works, and it's really just that part that matters. If he uses the technically incorrect but easy to understand notion that power is delivered by the L1 and L2 power cables that distribute power throughout his house on red and black wires, and returns back to the panel on the white wires, and that the L1 and L2 power sources are each 120 VAC relative to the neutral, but 180 degrees out of phase so that there's

240 VAC between them, then he knows more than most homeowners and enough not to electrocude himself, and that's what counts.

And, so far as I'm concerned, I'm going to drop this thread in favour of doing something more productive with my time.

I'm going to see if I can open my mouth so wide that my head turns inside out. I'm just wondering if I can do it. It may take some time to find out for sure if I can do it or not.

[bud--]

Seeing as how we are talking about transformers, and to further confuse Danny... And to bring in 2-phase...

Distribution in a relatively large building may be 480/277V 3-phase. Large motors are 480V 3-phase and lighting is 277V. Scattered around the building are 480/277V to 208/120V transformer (all of this is 3-phase, wye). There are 3 transformers in one assembly.

Relatively small transformers can be made with 2 transformers in one assembly with the transformers in a Scott ( or T) connection. The 2 transformers operate at true 2-phase, 90 degrees out of phase. Long live

2-phase.

The problem with this connection is it screws up the power factor and the current rating of the transformers has to be lowered. The same thing happens with open delta.

[bud--]

I don't know what "engineered to take it all into account" means.

Engineers would rather not have these earth currents. One place they are quite detrimental is on a dairy farm where "stray currents" can have a really large effect on milk production.

[bud--]

My recollection is transmission is wye at the source and delta at the end (that is transmission line connections to the transformers). This is not something I ever work anywhere near.

Distribution at my house is 13.8kV phase-to-phase and 8kV phase to neutral. I have an 8kV distribution wire (and distribution neutral) running down my alley. I believe most distribution is wye. All the distribution transformers I see have one high voltage insulator, which has to be wye.

[bud--]

I didn't read Danny's other sources. I am really tired of his arguments. Interesting they are all the same thing.

I did see that Brain started "How things work" (I have seen other nonsense at that site).

Brain is presumably an EE. When I graduated there had been no reference to the NEC, and no practical information about power systems, and in particular earthing. Brain certainly shows no comprehension. krw, I think, said most EE course work is electronics. There are at least 3 other EEs here. I haven't noticed any have particular information on power distribution that they got in school.

I have not figured out how "she" has anything to do with the "piece" except "she" is a prof at the same college that put up the "piece".

But Danny found it on the internet....

Hey, didja hear that O J Simpson was framed by Romulans that beamed down from a cloaked war-bird and tampered with the evidence in the crime lab. If you don't believe it show me someone who says it isn't true.

[bud--]

I think it was used in the early days of the REA.

Where has it been used in the US in the last 50 years.

I don't remember ever seeing transmission or distribution lines without a neutral.

[Ed]

So I'm confused. Are my 240 volt appliances single phase or two phase?

[Dean Hoffman]

At least three of the local REAs use the 480v corner ground delta for irrigation here in south central Nebraska. One uses the 480v center tap delta. I haven't seen any circuit breakers used for irrigation. Everyone still uses fuses. Electricians do use breakers for grain bin and building power though. There are a lot more circuits needed for grain handling and buildings. Plus condensation isn't the issue it can be with irrigation.

[John G]

Absolutely l-)

[Dean Hoffman]

Cut a bunch to keep AIOE happy.

Article here

talking about power distribution. It was written by a fella with a BSEE and an MSEE. He spent a bunch of years working in the power industry. He writes about a possible project in Alaska. Single wire earth return similar to what the Aussies do.

He says: A single wire, ground return circuit will require a waiver from the Alaska legislature or Department of Labor since it does not comply with the NESC. However, the author does not believe that the single conductor, earth return circuit should be considered and firmly believes that a multi-grounded, neutral be considered on all single phase and three-phase, four-wire circuits. End quote.

The fact that using the earth return system requires a waiver implies that it is used very infrequently.

[Nightcrawler®]

It would appear that the concept of electrical continuity and being part of a circuit is rather lost on some people. Does the ground perform an important function? Yes. Is it a current carrying entity in the circuit: No. Does it carry stray voltage? Yes. Does it carry stray current? Yes. Does the fact that it does carry voltage and current make it part of the distribution system? No.