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Uses of an Isolation Transformer

  1. Oct 16, 2009 #1
    I want to know what do we use an isolating (1:1) transformer for.

    My book says it is to "protect against electric shock". It doesn't say how.
    I tried to ask my teacher but he didn't know.

    I also have looked at http://en.wikipedia.org/wiki/Isolation_transformer" [Broken],
    but I could not understand the article fully because of the technical terms.

    Can somebody please tell me the uses of an isolation transformer and how does it work?

    Thank you
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Oct 16, 2009 #2
    If your circuit is isolated form the mains (where neutral is gounded somewhere) by an isolation transformer, you can touch any part of your circuit on the transformer secondary and any grounded object (e.g., plumbing) and not get shocked (or worse). This is because there is no conducting path between the transformer primary and secondary.
    Bob S
  4. Oct 16, 2009 #3
    In industrial/commercial power distribution systems one leg of the AC supply is tied to earth. Hence touching the other leg while in contact with the earth will cause electric shock. The isolating transformer uses the ground-referenced AC to generate a magnetic field which is coupled to the secondary winding of the transformer. This generates a new current, which is not referenced to earth. This is why it is (probably in the States as in New Zealand) illegal to earth an isolating transformer.
  5. Oct 17, 2009 #4


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    Gold Member

    The first use of this idea was the 'razor only' electrical outlet that was originally the only electrical supply allowed in a bathroom. As mentioned previously, the idea is that the user has no direct contact with mains power. This, of course, came about several decades before the invention of GFCI technology.
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