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Mains isolation transformer (Va.)

Discussion in 'Electronic Equipment' started by Ville Voipio, Apr 21, 2004.

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  1. Ville Voipio

    Ville Voipio Guest

    Due to some rather annoying industrial ground loop problems
    (piping potential is far away from the network PE) we would
    need a mains isolation transformer:

    - 115 Vac : 115 Vac / 60 Hz
    - 300 VA
    - UL (or other appropriate) certification

    A very simple device, no doubt. Unfortunately, our service guy
    is in Richmond, Virginia. I would know where to get
    such a transformer for 230 V/50 Hz on this side of the Atlantic,
    but that does not help much...

    So, if you have any idea where to find the transformer in
    Virginia, that would help a lot!


    - Ville

  2. They're easy to mail-order, from places like Digikey, Jameco, Mouser,
    Newark, Grainger... 300VA is an easy size to find.

    However, if you are using this in an industrial setting you should be
    working with a licensed electrician to be sure your work meets the
    electrical code. You can't just lift grounds!

    In particular, here's something I think you can't safely or legally do: plug
    an isolation transformer into circuit "A"; plug equipment "X" into the
    isolation transformer; and ground "X" using a ground wire that runs to
    circuit "B", separately derived from "A". Especially if the ground wire
    isn't a rated conductor of adequate gauge. The reason is that if the hot
    output from the transformer shorted to ground, no circuit breakers would

    If this is just a temporary thing to get some test gear working, forget I
    said anything :)
  3. Ville Voipio

    Ville Voipio Guest

    Thank you! I tried Digikey (not in stock) and Newark (something
    in stock), but Jameco, Mouser, and Granger were less familiar.
    It seems that Mouser have some good parts, so that may solve the
    Yup. Would not cross my mind to do anything in somebody else's
    plant without having their electrician taking the responsibility...
    Extremely temporary.

    Thanks once again!

    - Ville
  4. Another electronics distributor I didn't mention is Allied, at, who are showing stock on a Hammond 300VA
    isolation transformer for about $73.

    Grainger (note the 'i') is an industrial-supply chain. They do mail order
    but they also have retail outlets; so if you're in a hurry you may be able
    to find one close to you. They're a great source for replacement motors,
    pulleys, belts, AC capacitors, things like that, as well as selling
    everything else industrial from hand cleaner to drill presses. However,
    they tend to be expensive.

    (I have no association with any of the sources mentioned, by the way.)
  5. Try Grainger. and search for keywords isolation
    transformer. I found several.
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