240V 3 Phase question

Discussion in 'General Electronics Chat' started by jmaty23, Jun 11, 2008.

  1. jmaty23

    Thread Starter New Member

    Jun 11, 2008
    I work in an industrial food processing plant with a 480V 3 Phase supply power stepping down to 240V 3 Phase power using a transformer. When I go from 1 leg of the secondary power to ground I get 230V, the second leg to ground I get 230V, the third leg to ground is 0V. When I go from leg to leg I get 230V. My question is why do I get 230V leg to leg and why does the third leg have 0V?
  2. mik3

    Senior Member

    Feb 4, 2008
    Can you tell us the serial number of the transformer or something about it as we can find information about it?
  3. thingmaker3

    Retired Moderator

    May 16, 2005
    Sounds like a 3-wire delta with grounded hot leg. I didn't think they were used any more. How old is this transformer?
  4. gerty

    AAC Fanatic!

    Aug 30, 2007
    I agree, on both counts. Last place I saw that used that was 480 v w/grounded hot leg, something about that just doesn't seem right.
    Last edited: Jun 11, 2008
  5. jmaty23

    Thread Starter New Member

    Jun 11, 2008
    The transformer is a Square D Sorgel General Purpose
    Cat # 150T6h
    Style # 35149-28212-024
    No serial #
    The date code is 0608

    The transformer was installed about a year ago.
  6. subtech

    Senior Member

    Nov 21, 2006
    Your connection is called a corner grounded delta. Not that uncommon in industrial settings. One leg of the delta is connected to earth. This connection may or may not be intentional. If there is a plant engineer available to you, he should be consulted.
    Last edited: Jun 11, 2008