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  1. #1

    Default 3 Phase 240 480 wye delta floated high side

    Question on a 3 phase overhead bank,Transformers are wye 7970 floated high side.On secondary side its wired delta,voltages are 280 280 and 265 phase to ground.480 phase to phase on all other checks,why 265 volts on the one leg to ground but like I said 480 phase to phase with any other leg?No neutral on low side...
    Last edited by birdog37; 11-24-2017 at 02:54 PM.
    Birdog37: "Remember we're all on a journey in life, the only difference is, some people know it and some people don't."

  2. #2

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    Does the leg that has 265 volts come off of the lighting pot? Or the shared leg between the two outside pots?

  3. #3

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    Its the shared one on the outside. The 265 volt leg is from the outside transformers like you would on a regular closed wye delta 120 240 and wild leg 211 which would be like the one this 265 volt leg is tapped on.Remember these are 240 480 rated.The only difference is that on this bank there is no reference to ground on any of the transformers(except the lower tank ground) like your strap you would normally have on the middle transformer in the bank as your lighter tub. Hope I made myself clear.THX.
    Last edited by birdog37; 11-26-2017 at 08:59 AM.
    Birdog37: "Remember we're all on a journey in life, the only difference is, some people know it and some people don't."

  4. Default

    Quote Originally Posted by birdog37 View Post
    Its the shared one on the outside. The 265 volt leg is from the outside transformers like you would on a regular closed wye delta 120 240 and wild leg 211 which would be like the one this 265 volt leg is tapped on.Remember these are 240 480 rated.The only difference is that on this bank there is no reference to ground on any of the transformers(except the lower tank ground) like your strap you would normally have on the middle transformer in the bank as your lighter tub. Hope I made myself clear.THX.
    Simplify.

    I'd isolate the bank and hook them up single, see what you get then. Sounds like it could be polarity issue, x3 to x3, etc.

  5. #5

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    Thats sounds like the next step to try.Guess i never really considered polarity because there only 15 KVA transformers.I know on the leg Im having issues with they doubled up the conductor under the same lug to make there tap for the service instead of bonding it down below they stuck it under the same transformer lug.Thanks any other thoughts anyone?
    Last edited by birdog37; 11-26-2017 at 11:11 PM.
    Birdog37: "Remember we're all on a journey in life, the only difference is, some people know it and some people don't."

  6. #6

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    I hate to have more questions than answers but I'm trying to wrap my head around this. Was this a trouble call? What does this particular bank feed? Are any of the pots in the bank dual voltage/ dual wound on the primary side? I can only assume that you got a call and that is what led you to check the voltage on this bank.

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