Discussion in 'Homework Help' started by cpleng7, Jan 4, 2011.

  1. cpleng7

    Thread Starter Active Member

    Dec 18, 2008
    I have a three phase power source which 415V line to line .
    and I have three transfomer 240 - 12V.
    Now I have a task to step down the three phase system to 12V each phase.
    How I can do?
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    You could take 2 transformers and put the primaries in series. Two 220 volt primaries add up 440 volt. The secondaries can be placed in parallel for 12 volts out.

    You would need 6 transformers to do this for all three phases.

    Otherwise you need the proper voltage step down transformer.
  3. Adjuster

    Well-Known Member

    Dec 26, 2010
    415V line to line. How many volts line to neutral? Or if you don't have a neutral, from line to a star point?
  4. edgetrigger


    Dec 19, 2010
    How many wires your three phase has. If it has 4 wires marked RGB and N then it is a star connection. The voltage between any of R,G,B wrt N is called the phase voltage and will be around 240V for 415v 3 phase system.

    Connect the primary of the transofrmer between
    R & N
    Y & N
    B & N

    now the load is also distributed equally. The output of each 240-12 step down will give you 12 v as desired.

    If you dont have a star connection then you have to have a star-delta tranformer.