An open wye connection?

[366Delta]

I’m curious about the open-wye connection. Open delta a bit easier to understand—the other one I don’t understand. This is a quote I found:

Yes a hookup with a Wye secondary is possible. It is possible to use 2 transformers for example in a 3 phase 208 or to use 3 transformers for a 3 phase 208. Either hookup can be made in a Wye with only 2 primary phases and the system neutral. Very uncommon but actually have the 3 pot example in the area where I now work. The 2 pot hookup must have one pot with external secondary bushings. We talked about this once before several years ago. dbrown20

What would this look like, diagram-wise?

[wtdoor67]

I believe we have discussed this about 3 times. If you work for a power co. you can probably find a diagram of this in some of their obscure transformer hookups.

I can give you a description of it if you persist and you can make your own drawing.

If you're not satisfied then I'll get my spouse to help me post it etc.

[kooman]

i think the primary side hookup would be H1 on pot #1 is to phase A, H2 on pot 1 jumps to H1 on pot #2 and to neutral, and then H2 on pot #2 to phase B. someone correct me if this is incorrect, i have never seen one but im just going on memory, and i have had a few longnecks tonite so.............:)

[Pootnaigle]

I bleve the 208 causes sum misunderstandins. Ummmmm on a 208 bank (wye wye) phase to phase voltage is 208 or therebout but any phase to ground is 120.
A three phase bank wye delta or open wye delta has a high leg voltage of 208 phase to ground, but 240 phase to phase, and 2 legs of 120 phase to ground. They aint the same critters.

[wtdoor67]

I have known of this hookup about 30 years. It's using an open wye (2 primaries and a neut) line and one version can use 3 pots and the other uses 2 pots. In the two pot version one pot must have external secondary bushings. Pole mounted pots are the only way I know. I guess somehow you could conjure one up with pad mts.

After knowing of it for a long time it was after 1992 until I actually saw a working bank of such. The only one I have seen is the 3 pot version.

[wtdoor67]

Here it is. I guess the top could be Open/Wye. Don't know about the bottom.

[ratbastard101]

Door those are some weird looking banks. Thanks for the info, wish I could build both of them personally and see how they work.

[rcdallas]

Someone once told me over yonder in Chicasaw, OK pronounced (chick-a-shay) off I-44 you'll see one... ;)

[wtdoor67]

H E Bailey Turnpike. The last toll gate N. bound toward OK City. It's on the south side of the Toll booth. 3 pot version with only 2 phases of 13.2 and a neutral.

If you ever have a training session with those little mini pots etc. in a classroom, then try one, they work fine.

[wtdoor67]

Danny, you, and Carl Fl&%y@, should charge IBEW Local 1002, a monthly fee to keep living in OK, If you two ever moved the IQ knowledge of the state would drop by half. You already had a great loss of knowledge when Jim French, hit the big Tee-Pee in the sky. I just wish you would have come to Kansas and worked for us when we talked after you retired. As many times as our paths crossed we have never worked together. Wouldn't a team like us strained the patients of any GF? :eek:

Don't give me too much credit. I know enough to keep myself safe and maybe turn out a little work. Too be honest there is so damn much I don't know, and will never know it makes me feel rather puny when I think about it.

If I had it before me again I think I would learn a lot more about transmission sagging and probably sub construction. Still I'm gratified to know what little I do know.

To me the best thing is to exchange experiences with other guys as you always learn so much that way.

So much stuff should have been written down. I remember talking to a guy once who described some work they did revamping the power generation plant of a muni. When they put everything back the rotation was wrong. No biggie they thought and just rolled 2 phases. Didn't fix it. He related they had to put it back exactly as it was to start with. I think he said it had something to do with how the brushes on the generator were worn. He was a technical guy and basically an engineer but I wish I had wrote down things like that while it was fresh in my mind.

[Pootnaigle]

Ummmmm dont be shortin yerself dude, Your knowledge shines through all the hullaballo.I recognized from day one that you were a linemans lineman.I bleve you were Danny Brown then.There are a few others on here that truely try and help the new guys, But yer the go to guy fer teknikal stuff, least ways on distribution. If I hadda transmission question I would Prolly ask Steve n have lil doubt that his would be the correct answer.John Bellemy aint no dummy either but regretablly we dont see much of him nowdays.I spoze the important thing for these younger guys to glean from all this is that knowledge is power, Get all you can, anyway you can, about as much as you can.Knowledge keeps you safe, Knowledge helps you work smarter instead of harder, and its recognised by your peers.

[366Delta]

Thanks again guys. Once again you have provided a wealth of information. {I am, by the way, telling everyone I meet that there is a lineman forum.}
As for “wtdoor67”, #6, they say a picture is worth a whole lot of words. I wish the page was a shade clearer, but I got the general idea. I believe the 2nd diagram is the one I occasionally see in these parts. {Rural Central Illinois} How two hot wires coming to a farm could supply a 3 phase service puzzled me to no end, and kept me awake at nights. But I think I have it now. I’ll have to make it a point to check for a transformer with 4 bushings. I could be learning something---it can be a scary process.
My father, a retired union electrician who worked mostly in factories, refineries, warehouses, etc., has always told me he has a lot of respect for linemen, and would never want to do their job. He has worked in factories that had 4160 piped in though---some big motors.

[wtdoor67]

I believe 167 KVA and larger have 4 external secondary bushings.

[rcdallas]

I believe 167 KVA and larger have 4 external secondary bushings.

I believe you are correct....though I believe we have some 333's that have just 3 bushings.

[wtdoor67]

I remember hanging a 333 once. It was a stepup. Stepped up single phase 7200 to 19.8. For awhile I think 333's were the largest pole mts. made but I understand there is a bigger one now.

I recall looking once in the spec book and seems the pole had to be about a class 2 or larger. Purty big pot to hang on a pole.

[wtdoor67]

Here's a cut away of a CSP. It's a double bushing primary. Not very good quality. Solly. CSP's came out in 1933 according to the brochure.

[rcdallas]

The second lever on the secondary breaker handle is an overload handle to buy you a bit of time for a work later change out.

All the second lever does is strengthen the spring on the secondary breaker internally just enough to get the lights on for the time being. Too bad not all CSP's have them.

[LAMartin.CVEC]

I'm the odd freak that loves "bastard banks" this is one of my favorites. Two others are the 480 2 pot single phase primary and the 3 phase 877 or "Draw bridge" bank.

I find it awesome what you can do once you realize that transformers are just coils and ratios.

Thank you Mr. WTdoor for sharing this info, I wish more lineman were interested in this type of thing; perhaps they wouldn't be so skeptical of engineers! Who knows--if we as lineman--were more educated in WHY what we build works, we'd need less people to explain it to us! lol

I'm still trying to explain how you can ground a "corner" to some apprentices, ahh the brutal beauty of delta, it don't get much better than a perfect triangle!

thank you and work safely,

LAMartin
Journeyman Div III
CVEC

[surfinlineman]

I was checking the original post on this one, and the question was an "OPEN WYE". Any reference to an "open" bank means that you are using just two pots whether it is an open wye or an open delta. On an open wye, that would mean two phases and a neutral. So you would use "by convention" H1 on both pots for phases (A and B), and H2 on both pots for the noodle.
In CA working outside, we have so many different primary voltages, because there were so many small utilities originally, and we have some areas that started as rural farm communities and are now urban. The open wye banks are seen in areas which had a "V" system, two phases and a neut, so you could build less expensive two pot banks, giving farmers 3 phase power to the well and barn, 120 to the house.

[hotwiretamer]

I was checking the original post on this one, and the question was an "OPEN WYE". Any reference to an "open" bank means that you are using just two pots whether it is an open wye or an open delta. On an open wye, that would mean two phases and a neutral. So you would use "by convention" H1 on both pots for phases (A and B), and H2 on both pots for the noodle.
In CA working outside, we have so many different primary voltages, because there were so many small utilities originally, and we have some areas that started as rural farm communities and are now urban. The open wye banks are seen in areas which had a "V" system, two phases and a neut, so you could build less expensive two pot banks, giving farmers 3 phase power to the well and barn, 120 to the house.

I've only seen pots with 4 secondary bushings on 167kva and larger. Seems like thats a pretty big xfmr for a well or barn. (If your talking about the Open Wye bank). What about the available fault current with a trans that big? Do they make 4 bushing pots in smaller sizes?:confused:

[lewy]

Our 75 KVAs have 4 bushings

[hotwiretamer]

Our 75 KVAs have 4 bushings

I stand corrected. I guess it makes sense that a xfmr manufacturer will build whatever the Utility requests!:rolleyes:

[surfinlineman]

I'm the odd freak that loves "bastard banks" this is one of my favorites. Two others are the 480 2 pot single phase primary and the 3 phase 877 or "Draw bridge" bank.

You'd love the three pot grounding banks that SDGE uses to create a neutral on the delta system for underground dips.

[rcdallas]

I'm the odd freak that loves "bastard banks" this is one of my favorites. Two others are the 480 2 pot single phase primary and the 3 phase 877 or "Draw bridge" bank.

You'd love the three pot grounding banks that SDGE uses to create a neutral on the delta system for underground dips.

Ok...you opened the door now it's time to feed my brain.

I've heard of the 3 pot grounding bank, but I'm not sure how it's wired nor why you would use it on an underground dip. Would you use it so the cable can fault and lockout easily?

Never heard of a draw bridge bank...what is it?

3 phase 877, that for some kind of oil field? Is it a wye bank?

480 2 pot single phase, eh? That nothing more then parrelling the secondary coils together to make for example a 100kva out of 2 50 kva's?

[LAMartin.CVEC]

Ok...you opened the door now it's time to feed my brain.

I've heard of the 3 pot grounding bank, but I'm not sure how it's wired nor why you would use it on an underground dip. Would you use it so the cable can fault and lockout easily?

Never heard of a draw bridge bank...what is it?

3 phase 877, that for some kind of oil field? Is it a wye bank?

480 2 pot single phase, eh? That nothing more then parrelling the secondary coils together to make for example a 100kva out of 2 50 kva's?

A 3 pot grounding bank is is simply a wye delta bank with the wye grounded on the high side it is used on delta systems to provide that "neutral" connections for the concentric it is also used in ug that works with SWER. As to why it is used you answered your own question sir.

The 480 2pot has been show here before just tap the 2 pots together and move the ground strap to the left making full use of the coil. It can be done 240 or 480 depending on the pot size/winding.

The 877 or "draw bridge" bank is just that a bank we have in a few places here in Va. that operates a Draw bridge. they are wye in nature and built with 480 pots. Again move the ground strap to the left and everything should become clear.

Don't play coy Randy I've read several of you and mr Wtdoor's posts on banking:)

all in all good stuff!

work safely,

LAMartin
Journeyman Div III
CVEC

[wtdoor67]

The 877 or "draw bridge" bank is just that a bank we have in a few places here in Va. that operates a Draw bridge. they are wye in nature and built with 480 pots. Again move the ground strap to the left and everything should become clear.-----------------------------------------------------------------------

Randy, what LA Martin is talking about here is evidently a Wye/Wye bank using 480 pots. Nominally it would be an 480/832 in voltage but evidently the regulators or LTC is stepped up enough that it's actually 877 volts phase to phase. Those higher primaries such as 34.5 or 24.9 put out some pretty high secondaries sometimes.

[LAMartin.CVEC]

Yes Mr. WTdoor67 you have hit it square as they say. Most of our 24.9 runs hot on the sec side on all our applications 248 to 250 single phase have seen 507 to 511 on 480. All of the DB banks I know of are 34.5 high side so they most probably run hotter yet on the secondary side.

Most of our banks "settle down" a bit after start up and a load is consistent. (we have 24.9 and 12.4 on our system varied between divisions). After settling they still tend to run a touch "hot" if you will however, do to PFC I personally do not think that it is such a bad thing. Especially on our circuits were we have many single phase consumers and a large amount of commercial and industrial load.

Thank you and again, I enjoy threads such as this.

work safely,

LAMartin
Journeyman Div III
CVEC

[Pootnaigle]

Ummmmmmm we didnt offer any secondary voltage higher than 480 so this is a new bank to me. I do understand the hook up but is there also special metering involved? And is the secondary buss grounded or floated?

[rcdallas]

The 877 or "draw bridge" bank is just that a bank we have in a few places here in Va. that operates a Draw bridge. they are wye in nature and built with 480 pots. Again move the ground strap to the left and everything should become clear.-----------------------------------------------------------------------

Randy, what LA Martin is talking about here is evidently a Wye/Wye bank using 480 pots. Nominally it would be an 480/832 in voltage but evidently the regulators or LTC is stepped up enough that it's actually 877 volts phase to phase. Those higher primaries such as 34.5 or 24.9 put out some pretty high secondaries sometimes.

Dammit wtdoor, don't use my real name I don't want these guys to know who I am.. ;)

Never did the math to calculate the phase to phase of 480 but now I know. Always been taught delta doubles in voltage, figured it must of been wye. I have seen on our 12470/21600 pushing over 500 on some corner grounded banks.

[wtdoor67]

Poontangle, there's quite a bit of flat rate stuff with some outfits. Maybe that.

[rcdallas]

Only flat rate I've heard of was a typical guard light...though you never know. I would think it'd just be a typical CT setup on the secondary.

[wtdoor67]

Dammit wtdoor, don't use my real name I don't want these guys to know who I am.. ----------------------------------------------------------------------

I thought Randy was your code name.