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3 phase (Neutral) Transformer

  1. Jun 13, 2012 #1

    We have a project where we have to install an HVAC system but only a 3-phase supply is available. While that is fine for the motors inside the unit, it means that there is no neutral available for the control circuitry.

    I am aware that a "zig-zag" isolating transformer can provide a neutral point in a 3 wire system but I have not used it before.

    The control circuit will require approx 15A, what is the correct method of sizing the transformer, also is there any manufacturers out there that can provide this product?

    Attached is a possible solution, as it mentions the zig-zag option. Would this fulfill the requirement?

    Some details for our project:
    Available supply: 3ph 400V (400A Breaker)
    Control Circuit: 1ph 230V (24no 230V Contactors & 4no Siemens PLCs - Approx 15A)

    Attached Files:

  2. jcsd
  3. Jun 13, 2012 #2


    User Avatar

    Staff: Mentor

    Welcome to the PF.

    You need to use a licensed electrician to help you with this project. We cannot help you here.
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