wiring for a 220v to 110v step down transformer

Discussion in 'The Projects Forum' started by lokeycmos, Apr 13, 2011.

  1. lokeycmos

    Thread Starter Active Member

    Apr 3, 2009
    could someone please look at the schematics i posted. i have a 1kva step down transformer so i can use 220v on my 110 volt A/C. i tought the one i drew up would be the way to wire it, but i found another schem on the internet. is one better than the other? here is a pic of the xformer too.
  2. GetDeviceInfo

    Senior Member

    Jun 7, 2009
    Your image indicates a two winding isolation type transformer, so you hook it up like your hand drawing. The second circuit you've shown is an autotransformer connection which requires a single wound transformer specifically designed for that approach.

    Look at the specs for your transformer which should include terminations for it's various applications.
  3. eblc1388

    AAC Fanatic!

    Nov 28, 2008
    What does A/C stands for? Air-conditioner?

    They are both correct because the type of step down transformer is different in each case. The circuit has to match with the type of transformer used. The first transformer has separate primary and secondary winding and will provide electrical isolation of the load to the source.

    The remaining one is often called the auto-transformer with a tapped winding to give the output voltage. It does not provide electrical isolation. However, the size of such transformer would be smaller with the same rating as compared to the two winding type thus they are usually found in step down application.

    I can't tell which type of the transformer you have at hand from the image.