Page 1 of 2 1 2 LastLast
Results 1 to 10 of 19
  1. #1

    Default 3 Phase 240 480 wye delta floated high side

    Featured Sponsor

    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 03:54 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

    Default

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

  3. #3

    Default

    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 09:59 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

    Default

    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; 11-27-2017 at 12:11 AM.
    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

    Default

    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.

  7. #7

    Default

    Quote Originally Posted by Lineman North Florida View Post
    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.
    Yes there having issues for a long time especially with there welder.I was told there going to put a voltage recorder on it so i went to see what i was up against.Polarity is not an issue and yes the xformers do have taps set @ 7970,it was 2400 @ one time.There not dual rated on low side.I believe the xformers are too small and the run is lengthy too.As far as voltage difference Im guessing when you go to ground as far as delta you can get a difference in voltage.Like i said the phase to phase voltage is fine but thought that the 265 might have been something to dig into.
    Birdog37: "Remember we're all on a journey in life, the only difference is, some people know it and some people don't."

  8. #8
    Join Date
    Mar 2003
    Location
    Jersey
    Posts
    2,512
    Blog Entries
    1

    Default

    I'm missing something, you're reading 280 280 265 and 480 cross phase. Why are you getting 280 phase to ground on a 480 straight power bank? 265 on the wild leg. Allowing 5% over/under voltage phase to ground acceptable would be 252 per leg on lighting pot. Am I reading this right?
    "It is not the critic who counts:The credit belongs to the man who is actually in the arena" Teddy Roosevelt

  9. #9

    Default

    That is correct not sure why either i have checked this twice.
    Birdog37: "Remember we're all on a journey in life, the only difference is, some people know it and some people don't."

  10. #10
    Join Date
    Mar 2003
    Location
    Jersey
    Posts
    2,512
    Blog Entries
    1

    Default

    Featured Sponsorr

    I'm just grasping straws here, did you check the name tags on the pots?
    "It is not the critic who counts:The credit belongs to the man who is actually in the arena" Teddy Roosevelt

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •