Question about transformers

Discussion in 'General Electronics Chat' started by Thuktun, Apr 2, 2015.

  1. Thuktun

    Thread Starter New Member

    Apr 2, 2015
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    0
    Hello everybody, I'm new to electronics as a hobby so bear with my lack knowledge. I have access to all sorts of electronics junk in my job and I learned long before I got into this to not throw anything away. I have a couple of transformers labelled 347v 60hz 120v 30va. It's my understanding this steps down 347v to 120v at a max 1/4 amps, correct? My question is, can I use this to step down 120v and what would be the effects? Meaning I would get about 40v but what amperage? Would it still be 1/4 amps or would it still be 30va so work out to 3/4 amps or would it be some other value all together?
     
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    945
    using 30 VA is the safe bet, but you likely could draw 10-20% more without a problem. monitor temp rise to determine limits. intermittent use allows higher current draws with cool down in between active periods.
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
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    If you ever needed 347vac you could run it backwards off of 120v!;)
    Max.
     
  4. alfacliff

    Well-Known Member

    Dec 13, 2013
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    I sould not increase the output current, it's set by the wire size, and keeping the va the same would double the currrent.
     
  5. #12

    Expert

    Nov 30, 2010
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    alfacliff has it. The diameter of the secondary wire is designed to carry 1/4 amp. Try to get 30 VA out of that at 1/4 the voltage and the heat goes up to burning level after just a few minutes.
     
    Gdrumm likes this.
  6. Thuktun

    Thread Starter New Member

    Apr 2, 2015
    15
    0
    Thanks guys. I figured that was the case, just wanted confirmation.

    I got some magnetic ballasts too, this is the biggest. I have no idea what I may use them for.
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
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    They are stamped auto transformers and are Holophane!!
    Max.
     
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