3 phase wye/delta bank with wild leg?

[freshjive]

Just curious, does anyone have the drawing or diagram of 3 phase wye(primary) delta(secondary) XFRMER bank with a "bastard leg" to get 120 out of one of the legs for lights? Do you leave just one strap on a bushing inside the guts of the Xformer to do that, instead of just putting the 2 straps on each hot leg to get straight power? I used to know how to do it, but I just can't seem to remember, so any help would be great, as I'm sure someone here is very knowledgeable about different wiring schemes for Cans. If someone could just draw the three cans and make a picture of them with the wild or "bastard" leg that'd be swell, cuz I'm more visual than having to....Thanx much for any info fellas

[lewy]

I do not have a drawing handy, but I remember SBatt posting a web site that mite help. It really is easy though you just 2 transformers hooked up in series without the ground strap to give you 240 & on the one transformer you ground the x2 & that transformer will give you your 120/240. You just hook up the 3 for a 240 delta.

[Pootnaigle]

Ummmmmmmm using 3 pots remove the secondary ground straps on the outside 2. start by tying the right hand bushing on the far left pot to the left hand bushing on the center pot. then the right hand bushing on the center pot to the left hand bushing on the righthand pot. All that is left is the left hand side of the outside pot to the right hand side of the other outside pot.If you ground the center pots middle bushing your voltage will be 125 to grnd or 240 phase to phase on the 2 shortest busses. The longer buss tying the 2 outside xfmrs will be the wild leg and voltage will run bout 216 or thereabout. Just remember delta always uses opposing bushings on each pot. Ummmm purty poor esplanation but Hell I'm gettin senile.

[freshjive]

no poot you ain't senile it's just so hard to remember all of the damn hookups cuz they're are sooo fuggin many of em...I wish someone could draw a pic and put it up on this post.....LIke I said before any help is appreciated thanx guys...

[wtdoor67]

no poot you ain't senile it's just so hard to remember all of the damn hookups cuz they're are sooo fuggin many of em...I wish someone could draw a pic and put it up on this post.....LIke I said before any help is appreciated thanx guys...

Comeon. There are basically 4 common ways to hook banks. There are some kinda strange things but you're not likely to run across them. Break out a Kurtz book.

Use Batt's link or do some googling.

[Pootnaigle]

No there are only 4 different configurations for 3 pot banks. There may be some variation such as a floating buss on wye stuff.. But delta is delta on all of em.
Wye tells you one hot bushing on each pot is used for a hot( must be the same bushing left or right throughout the hook up and that the other bushing is grounded or floated.
Delta tells you that each right bushing ties to the left bushing of the next pot.
Dont let it get any harder than that its simple stuff.
.

[Pootnaigle]

Ummmm Steve that wud be wye-wye, wye-delta, delta-wye, or delta-delta.

[rob8210]

Wye - delta. Float the primary neutral. What Poot says is right. And yeah tranny hookups are pretty simple, its just the engineers and techs that make it sound so complicated. Oh yeah and your cans have to have 2 insulated primary bushings.

[kooman]

yea good info, thanks for posting it. im not use to seeing subtractive polarity transformers used in most diagrams though.

[Lineman North Florida]

yea good info, thanks for posting it. im not use to seeing subtractive polarity transformers used in most diagrams though. I saw that to,all of the transformer where I'm at are additive occasionally some of the guys will run up on one in a bank where we have taken over some lines from other utilities in territorial agreements and you guessed it will replace it with an additive:D

[rcdallas]

Subtractive or additive it doesn't matter the hook up is exactly the same...what gets different is when you use an additive mixed in with some subtractive.

That or feed in an H2 for some odd reason while the others are fed in H1...BUT I won't go there. ;)

Here it's not uncommon to see one fed in H1 and the other H2 on a open delta.

[Trbl639]

That's right RC.......see that a lot in S Arkansas in the oil patch!!

Good post sully, but ya forgot...some places are using wye pots......2 bushing secondary...some of the youngsters might get lost when they see em the first time!:D Around here, it's not unsual to see 3 pot wye banks, with the hot (secondary) on the right, and the bank next pole down is cut to the left..if I remember right our spec called to cut em center to right....but it just depended who built it..hell they might be cut center/right...center/left....or even outside to outside!!


When I was at Little Rock AFB, working nights, many years ago........got a voltage complaint call, from the A/C guys... Y/Y bank,voltage was good all the way across, but none of the 3 phase air units would run! Scratched my head some on that one!! Turns out day crew had replaced the bank pole (deadend)...removed everything, put the new wood back in the same hole and then put everything back in the air.....they weren't paying attention when they wrecked it out, and I had to figure it out! all pots were 2 bushing primary, all were marked Additive, but one had been re-wound years earlier and put in that bank.........but the name plate had NOT been replaced, and that pot was wound Subtractive!!! I'll be honest on that one, I scratched the crap outta my head, I couldn't figure out squat and was ready to give up, but decided to call my resident expert, My Old man, and he suggested checking polarity and Bingo, there it was.........before the day crew came in the next day, in 4 inch high RED letters, SUBTRACTIVE was painted on that can!!!:D:D

[rcdallas]

When I was at Little Rock AFB, working nights, many years ago........got a voltage complaint call, from the A/C guys... Y/Y bank,voltage was good all the way across, but none of the 3 phase air units would run! Scratched my head some on that one!! Turns out day crew had replaced the bank pole (deadend)...removed everything, put the new wood back in the same hole

I remember asking something similar to this once in a class about slapping the ground strap in a different position from the other two cans on a wye/wye and was just told that it wouldn't work.

I have seen where on a delta bank if you hooked up the tie bus wrong, say x3-x3 - x1-1 you'll just get some crazy voltages, like 340 on a 120/240...what I'm getting at is when you checked voltage, everything was still made up and you where still getting 208 phase to phase? I can see that.

I can't remember exactly off the top of my head how to check polarity, it's something where you put 120 on the primary side and you check voltage on the secondary if its + so many volts or - so many volts it's one or the other.

edit:

I wonder what the rotation meter was doing to ya when you came across this...probably wasn't marked before ya got there.

[lewy]

I remember asking something similar to this once in a class about slapping the ground strap in a different position from the other two cans on a wye/wye and was just told that it wouldn't work.

I have seen where on a delta bank if you hooked up the tie bus wrong, say x3-x3 - x1-1 you'll just get some crazy voltages, like 340 on a 120/240...what I'm getting at is when you checked voltage, everything was still made up and you where still getting 208 phase to phase? I can see that.

I can't remember exactly off the top of my head how to check polarity, it's something where you put 120 on the primary side and you check voltage on the secondary if its + so many volts or - so many volts it's one or the other.

edit:

I wonder what the rotation meter was doing to ya when you came across this...probably wasn't marked before ya got there.
Yea you were pretty close when it came to checking polarity
The H1 bushing is connected to low voltage bushing directly opposite with a jumper
A volt meter is connected across the other high voltage bushing & low voltage bushing
the high voltage windings are energized with low ac voltage (120)
If your reading is above 120 the trans is additive below 120 subtractive.
Of course you can bank additive & subtractive transformers together.