Control transformer help

Discussion in 'The Projects Forum' started by Csowell, Jan 21, 2011.

  1. Csowell

    Thread Starter New Member

    Jan 21, 2011
    I have a 480/110 control transformer feeding an analog meter for monitoring purposes. The incoming voltage is approx 492 which is giving me a false reading of approx 540 on the analog meter. Can I find a transformer to make this read correctly or do I need to install a resistor in circuit?
  2. wayneh


    Sep 9, 2010
    I think more info is needed, such as how you are measuring now, why you think the reading is false, and more. Are you simply measuring RMS voltage with one meter and peak AC voltage with another?
  3. williamj

    Active Member

    Sep 3, 2009

    From the information given I am going to assume that the 480v is three phase. If that is correct then a high reading on one leg (or phase) is not that uncommon.

    Some of the more established (re older) providers still use Delta wound transformers for ditribution. It is on these Delta wound transformers that you encounter the "wild" leg, the one leg (or phase) of higher voltage.

    Most transformers (I think) now adays are "Wye" wound and do not have the "wild" leg.

    see attached