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Thread: 3 phase banks

  1. #1
    Maineiac Guest

    Default 3 phase banks

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    I was wondering what the procedure was in hooking up a 3 phase bank. How do you connect the transformers together, i know there is different voltages you can get but what is the most common ones. Also what is the process of testing the rotation consist of ?

  2. #2
    Join Date
    Feb 2006
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    Southern Indiana is home. But I work all over.
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    Boy did you just open a can of worms! lol Theres so many ways to make connections. Depends on the primary system and what kinda secondary volatages you need. If your a green horn ape don't worry about this stuff just yet. You have so much to learn before you get into banks and connections and trying to learn this stuff too soon just leaves alot of apes confused or in the dark completely.

  3. #3

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    Quote Originally Posted by Maineiac View Post
    I was wondering what the procedure was in hooking up a 3 phase bank. How do you connect the transformers together, i know there is different voltages you can get but what is the most common ones. Also what is the process of testing the rotation consist of ?
    We're going through transformers at NLC right now so let me take a stab at this.

    Open or closed bank?

    What are the transformers asking for?

    What does the customer need?

  4. #4

    Default Hmmm..

    120/240, open delta. H1 of trans#1 to a phase, H2 of trans #1 to b phase, H1 of trans #2 to b phase, H2 of trans #2 to c phase.

    120/240, delta, H1 of trans #1 to a phase, H2 of trans #1 to b phase, H1 of trans #2 to b phase, H2 of trans #2 to c phase, H1 of trans #3 to c phase, H2 of trans #3 to a phase.

    120/208-277/480 wye, H1 of trans #1 to a phase, H2 of trans #1 to neutral, H1 of trans #2 to b phase, H2 of trans #2 to neutral, H1 of trans #3 to c phase, H2 of trans #3 to neutral.

    If the pots are hooked up three phase wye on the primary side, and the secondary sides are delta, the H2's are floated. Alright lineman, how did this apprentice do?

  5. #5
    Maineiac Guest

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    On a closed Wye-Delta 240v straight power bank wouldnt you tie the h2's together with the system neutral instead of floating them? I know a Wye-Delta 120/240 bank is the hooked up the same as a straight power bank but it has a ground on transformer 1 at the x2 bushing. Im just looking through some of my bookwork on transformer connections and i dont understand why its Delta on the secondary side if you connect a neutral. I thought delta didnt use a neutral? And if your using a floating wye-tie and its not connected to the system neutral how is this realy a wye connection? I guess i dont understand Wye-Delta that well if anyone has any advise that be great. Also ive noticed that all the secondaries are color coded with marking tape, i know this has to do with the rotation but how do you do it? Im a 5th step apprentice and all ive hung so far is single phase transformers.

  6. #6

    Thumbs up Float it

    Always float the High side H2's. If you loose a transformer it well single phase and you well know you have a problem, if you tie it down you well have a open delta that is 57.7% of the bank.

  7. #7

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    Correct me if i'm wrong here.

    In the Transformer Lab we mark the secondary side with red, white, and blue tape. Red and white being the 2 hot legs and the blue being the Power leg. If the rotation needs to be changed it's done on the red and white hot legs. Don't confuse the power leg (blue tape) with a hot leg.

  8. #8

    Default I was going to rescan this material.

    http://albert-cordova.com/Y.jpg

    http://albert-cordova.com/delta.jpg

    I scanned them in at different times from an old book called The linemans and wiremans handbook.

    I have seen some stuff grounded on subs that I did not understand? The Engineer signs off on that part.

  9. #9

    Default Oh yeah,

    Dont forget to alley cat bad dog the winding leads. A and C on x2, B and D on x1( or x3 if its subtractive). Should have put that in the original post.

  10. #10
    Join Date
    Feb 2007
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    Quote Originally Posted by swetngblts View Post
    Correct me if i'm wrong here.

    In the Transformer Lab we mark the secondary side with red, white, and blue tape. Red and white being the 2 hot legs and the blue being the Power leg. If the rotation needs to be changed it's done on the red and white hot legs. Don't confuse the power leg (blue tape) with a hot leg.
    On a 3 phase hookup your rotation can only go clockwise or counter clockwise .
    If you want to change the direction you can change any 2.
    As far as markings go we use red white & blue but it could be anything some people use A B C .
    You want to be careful with colours because where I come from electricians use white as there neutral.
    This one is for Maineiac you can have 1 neutral only on your delta secondary(for lighting 120 V) as there is no reference to ground, hookup the second neutral & you would have a short.

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