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  1. #11

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    Quote Originally Posted by T-Man View Post
    I may not be following your question, But if you tie all the H1's or tie all the H2's to the floating neutral the connection is a WYE on the high side because there is a comon point tied. Forming a wye or a star connection.

    Now on a Delta you would tie an H1 on one tr to an H2 on the next and so on untill all the points are tied in series to form the triangle or delta.

    You can wire either of these primary conections to get a wye 120/208 or 240/ 477 four wire secondary depending on the secondary coils of the tubs.

    You can also wire the WYE or Delta banks to deliver delta 240 or 480 depending if the internal coils are wired in series for 480 or parallel for 240 (A to C and B to D for 240 - or B to C for 480)
    Maybe I should have stated that I was speaking of Wye primary and Delta on the secondary side, every closed Delta bank that I have ever built with Wye primary on the topside, the floating neutral will be tied across the 3 pots on the high side all together meaning all on H1 or all on H2,hopefully this helps clear up my original question.

  2. #12

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    Quote Originally Posted by Lineman North Florida View Post
    Maybe I should have stated that I was speaking of Wye primary and Delta on the secondary side, every closed Delta bank that I have ever built with Wye primary on the topside, the floating neutral will be tied across the 3 pots on the high side all together meaning all on H1 or all on H2,hopefully this helps clear up my original question.
    If your saying that if you swapped the floating tie,I wouldnt think it would change the rotation,never heard that asked before,and it is a good question.The incoming phases on the primary side would be the same,and the secondary would remain the same,it would change the polarity,but Id vote no,as far as changing the rotation...now if I was an apprentice again,that is one question I would ask of the supervisors/foreman when at the end of a verbal test,they asked me if I had any questions....did that once when I asked them about what leads what on a capacitor bank.....the reactance or the resistance.I used to know,but i seemed to have even forgotten that one.

  3. #13
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    When you change primary connections, you change rotation. So if the leads of the Floating Neutrals were hooked to the H1 bushings you would have one rotation, and if you installed the new bank with the floater hooked to the H2's. the second time the rotation would change.

    If you vectored this out you would not only see the rotation change, you would also see the polarity of the three phase bank change also. (do not confuse this polarity change with an additive or subtractive transformer winding) I'm saying in one case the vector diagram of the delta triangle would be pointing up and in the other example the vector diagram would be pointing down.

    So if A phase on the secondary was the upper most point of the triangle in example one, it would be the one pointing down in the second example. The left and right points would stay the same. Draw it out and you will see.

  4. #14

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    Quote Originally Posted by T-Man View Post
    When you change primary connections, you change rotation. So if the leads of the Floating Neutrals were hooked to the H1 bushings you would have one rotation, and if you installed the new bank with the floater hooked to the H2's. the second time the rotation would change.

    If you vectored this out you would not only see the rotation change, you would also see the polarity of the three phase bank change also. (do not confuse this polarity change with an additive or subtractive transformer winding) I'm saying in one case the vector diagram of the delta triangle would be pointing up and in the other example the vector diagram would be pointing down.

    So if A phase on the secondary was the upper most point of the triangle in example one, it would be the one pointing down in the second example. The left and right points would stay the same. Draw it out and you will see.
    And with that being said and back to the original question, it seems to me that on a delta bank no one can call rotation from the ground and be right 100% of the time without checking rotation with a meter.

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