The Wye/Wye for Jr.

[wtdoor67]

Jr. I have looked in all the info. I have and I can't find much touting the Wye/Wye. I'll keep watching. I think I read once it was easier to regulate or such. One suggested it was a little cheaper for the power co's as it's derived from ordinary house transformers which would lessen the variety of pots they would have to keep in stock. You know how they like cheap. I believe someone told me a long time ago that it was dreamed up by Ma. Bell.

I don't know if it matters but just about 100% of the time the pots are always the same size.

We'll figure it out.

I've done some googling, but really can't come up with much. I can't believe how much misinformation is given out on some of those boards. Some by apparently degreed engineers.

I'm sure some of the hands on here have some good input on this subject.

[wtdoor67]

The Wye Advantage

An advantage of Wye service secondary it that it meets the needs for 120-V single-phase, 208-V single-phase, and 208-V three-phase power in a building. Some other popular voltages are 480 V single-phase, 480 V three-phase, and 277 V single-phase.
Another advantage of the Wye is that there is no wild leg to burn out low-voltage, single-phase equipment. All single-phase loads may be connected to any winding of the Wye. Maximum and efficient use of all three conductors of the Wye can be utilized. The neutral or ground is brought out from the middle point of the Wye connection to be distributed evenly across the three phases.

Since the neutral wire is connected to the center of the secondary, which is common to each winding, the Wye is perfectly symmetrical. The power loads of the building can be balanced very easily.

Secondaries of transformers are often connected in Wye configuration to increase output voltage. Again, a line-to-line voltage encompasses two phases with a 120-degree angle between them. Line losses are reduced because the higher voltage allows for lower amperage; thus, the efficiency of the transformer is improved.

Tomczyk is a professor of HVAC at Ferris State University, Big Rapids, Mich., and the author of

[lewy]

New customers here can only have wye secondary conections & any time we are doing a construction upgrade or conversion we will cover any costs for an existing customer to switch from delta to wye.

[SwampRat JR.]

Thanks Danny, Almost word for word of what I have been told over the years, I think it must be the answer to give. They probably have to memorize it like a Bible verse.

I just remembered balanced loads, high voltage's, less line loss, from my experience, I could just **** up that delta all day long, Y is simple, like havin that neutral, delta seems to be more of a pain in the ass, but to each there own, but I would not hook up phase to phase delta high side on a three wire Y, I know if ya got no choice, it will work but just not a practice at the utilities I have worked at, but talkin to you, and readin stuff here it makes me slow down, sometimes it is so engrained, I see what I want to, but sometimes it isnt what I thought I saw, tunnel vision.

[Trbl639]

Door........

Most Every wye/wye bank I've ever built has had all 3 pots of the same size, and most all have had matching Impedance.........especially if the job was kitted.....all material for that job ordered and recieved at the same time.........if we had a burnout, if we could match the Impedance we could, if not, we got as close as we could, but sometimes we couldn't and we'd be back later changing it out, cause it would try to hog the load.........

for a long time, we always cut the pots.......then they started ordering Y-secondary pots in 120/208, and it's not unusual to see a 'cut 'pot in a bank with 2 bushing secondary pot..........

What is funny around Entergy, is to look at the y/y banks.......some are cut center/right......others cut center/left.......still some cut outside/outside, but I think the spec called for center/right...........I've had company crews in here, on storms and have em call me and ask what kind of bank was this or that, cause it was cut different from the part of the company they worked........

occasionally we built a Delta/wye bank, but later on, if it was a y-secondary, it was built y/y

The area I worked when I retired, I'd be willing to bet, that for every 1 closed delta bank I had 5 Y/Y banks........almost all (99%) of the downtown area was 'network', all banks phased together, but now, it's individual banks

[Trbl639]

Don't ya love it when ya got a hot-shot jman, who doesn't know how to cut one!!!

We had a scheduled outage one day at McDonald's..had 1 hour to replace a leaking 100KVA in a Y/Y bank that was leaking..........got the bank pulled off, and got the old pot on the ground and bagged......i asked the jman, if he had the pot cut right...he said yeah I'm not an apprentice.......I said ok, we'll see..........got the new pot in the air, buttoned up and it was the second one I closed in and kabloom!!!!!! It was a brand new one, anyway I checked it and he had cut it AB/CD!!! Had to hang the leaker back , cause by then it was close to being an hour and the manager at McDonald's was a *****, and she was *****ing!!! That was ok..the next outage was at midnight that night, and I made some OT, but this time I cut the pot myself!!!!

Years later, the same hot-shot got laid-off and then a few years later, re-hired, and then made T-man...........don't know how many times he called a crew for a bad pot in the oil field and when the crew got there, the pot was good and something else was wrong..........I think they sent him to the apprentice school when they were teaching apes transformers and hook-ups!!!!

[wtdoor67]

Thanks Danny, Almost word for word of what I have been told over the years, I think it must be the answer to give. They probably have to memorize it like a Bible verse.

I just remembered balanced loads, high voltage's, less line loss, from my experience, I could just **** up that delta all day long, Y is simple, like havin that neutral, delta seems to be more of a pain in the ass, but to each there own, but I would not hook up phase to phase delta high side on a three wire Y, I know if ya got no choice, it will work but just not a practice at the utilities I have worked at, but talkin to you, and readin stuff here it makes me slow down, sometimes it is so engrained, I see what I want to, but sometimes it isnt what I thought I saw, tunnel vision.

Jr. I worked for Pac Pwr in Wyo. for 8 years. We routinely used pots hooked delta on the high side for 4 KV, 12470 and 20800. I think a lot of that started with oil field built lines. Initially built just for 3 phase load only and only having 3 pot banks. I'm sure you could ask 10 different engineers and probably get 10 different answers.

And TRBL 639, as far as I know the only hookup where impedance is crucial is in a Delta/Delta. It's not a factor in the other 3 type hookups although I have worked with lots of people who have always been taught to heed it.

Also the 4 fuse thing you're talking about isn't the grounding switch for avoid ferro is it? I've seen it mostly starting with REC 14.4/24.9 systems. Ferro starts being a problem as you get into the higher distribution voltages.

[Trbl639]

Jr. I worked for Pac Pwr in Wyo. for 8 years. We routinely used pots hooked delta on the high side for 4 KV, 12470 and 20800. I think a lot of that started with oil field built lines. Initially built just for 3 phase load only and only having 3 pot banks. I'm sure you could ask 10 different engineers and probably get 10 different answers.

And TRBL 639, as far as I know the only hookup where impedance is crucial is in a Delta/Delta. It's not a factor in the other 3 type hookups although I have worked with lots of people who have always been taught to heed it.

Also the 4 fuse thing you're talking about isn't the grounding switch for avoid ferro is it? I've seen it mostly starting with REC 14.4/24.9 systems. Ferro starts being a problem as you get into the higher distribution voltages.

True...but for some reason our engineers always wanted matching Impedance on the Y/Y banks..........I was taught that Matching Imp was only crucial on the Closed Delta banks myself, so it was a change for me when I hired on with them..........but as a rule of thumb, if I could find 3 that matched, that's what I hung regardless of type of bank.....


I think that is what they were doing........I've never dealt with that type set up..but have definitely dealt with Ferro....not sure of the voltage where I saw it, but it was insulated for 14.4, but a lot of the co-ops down here are insulating about all of their new build and reconduct jobs with 14.4 insulators, even if the voltage is 7620/13.2........maybe someone with experience on the 4 switch set up will chime in..

[topgroove]

normally whenever you see four switches in the primary your looking at a wye delta. the wye primary float is floated. if you have the switch closed and loose a tub or phase the bank will go open delta. this could posibly lead to overloading the customer mains.

[wtdoor67]

Going from a closed Wye/Delta to and open Wye/Delta will not overload the customer's mains. It will possibly overload the transformer bank and burn up a pot though.

[Highplains Drifter]

On the underground side the wye/wye pots I have seen on three different Investor Own only used A and B phase, C was only a feed through. One time we built loop with five open wye/wye pots and C was only feed through them all. I have never asked the designers about this, I figure they are doing their job and I am doing mine, even though they are building an imbalanced feeder. Some of you other guys: are your UG pots open wye or closed for a wye secondary and if open do you switch and used C phase to balance your feeders?

[Pootnaigle]

If its a 4 switch Wye delta and its in service the switch on the primary floating buss should be opened to operate.......... and closed only to open up ( or refuse)one or all of the other pots. Once all 3 pots are closed in the floating buss switch should be reopened and left open. We used a deadblade 300 amp cutout type switch for this and standard fused cutouts for the 3 tubs. The thing about alll this that struck me as strange was say that bank was at the end of a very long 3 phase fused tap and one of the line fuses on the tap blew It didnt seem to affect the ferroresonance on the bank when ya closed in the tap fuse but it made a terrible mess when ya tried refusing one of the transformers in the bank without that 4th cutout closed.

[johnbellamy]

I ran across one this winter, I was on a different trouble call and I drove by a large super market, a door was open, the companies speck is to float it, a door was open on the bank, when I called dispatch, after taking care of the other problem, I asked them if the market had called in, they said no, it was kinda one of those things you have to wonder about, so I check the meter, a,b,c, are all lit and it is showing usage. So I fly up and see the high side wasn't floated, so I tell them I am supposed to de-energize the bank and break down the bank and test all transformers before re-energizing, they said since it was a large account a outage was not an option, I told them I got no problem tryin the fuse, but if she blows up, not on me, so I closed in and it held, they had a crew come in at night when they could take a kill and float it and put up the fourth cut out for the neut.

So I saw it for the first time in 18 yrs actually doin what they said it would because every place I have worked always float it.

Now some of the higher Y voltages they say always use a stinger or a fourth cut out, what we used to do is use either one of those if we tried and close in and she would blow back at us, then anything larger than a bank of 25s, where I work now speck is the fourth cut out, but everything is Raptor framed, and it makes a trap for killing the hawks, or whatever because of the long jumpers, and the small utility arm.

So like Danny said, it will over work the two remaining pots, and possibly burn them up, but in this case, it kept the business functioning with no outage, so I guess some might be a case by case or some exceptions to the rules.

After reading this board though, I am gonna try talkin them into useing the fourth cut out on the wye/wye banks, what are your thoughts?

[lewy]

On all of our banks that are fed 27/16 kv the secondary is either 120/208 or 347/600 & we would never use a 4th cutout. I thought this 4th cutout was only for delta secondary s

[Lineman North Florida]

True...but for some reason our engineers always wanted matching Impedance on the Y/Y banks..........I was taught that Matching Imp was only crucial on the Closed Delta banks myself, so it was a change for me when I hired on with them..........but as a rule of thumb, if I could find 3 that matched, that's what I hung regardless of type of bank.....


I think that is what they were doing........I've never dealt with that type set up..but have definitely dealt with Ferro....not sure of the voltage where I saw it, but it was insulated for 14.4, but a lot of the co-ops down here are insulating about all of their new build and reconduct jobs with 14.4 insulators, even if the voltage is 7620/13.2........maybe someone with experience on the 4 switch set up will chime in..

Trbl639 The only time that I have ran into ferro on 7620/13.2 is where URD was feeding an overhead closed delta, it would blow the lightning arr every time you tried to close in the last pot, I hung the 4th cutout closed it in then closed the pot and it did'nt blow the arr, opened 4th cutout and left solid blade hanging at neutral for the next man:D On matching impedence on banked transformers I ran into this just the other day as I was always taught that on banks it could cause you problems in some situations, long story short it was an oddball bank that we did'nt have a pot for with matching impedance so I called a rep at one of the tx manufacture's that we get pot's from and he told me as long as you are +or- 10% either way you won't have any problems banking it with the other 2 existing transformers in the bank. May want to check that for yourself as I can't state it for the gospel although I will be able to tell you after a while if those pot's in that bank holdout:D.

[johnbellamy]

Just bein a wise ass, but thanks. Some things I should not joke about. My Bad.:o

[rcdallas]

Over here it's 4th cut out on wye-delta. As far as the impedance I remember +/- 10% on delta banks.

I've seen some use a 100amp fuse instead of a solid blade on the 4th cutout.