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  1. #1
    Join Date
    Mar 2006
    Location
    Florida, jacksonville
    Posts
    94
    what is the resistance supposed to be on a 208/240 pri 24v sec 40 va transformer, i know when its bad, ive replace many in my time in the field, but was wondering!
    like what scale do i check it on? high res or low res? this one that i have right now is bad, no 24v on sec, and i have 240v pri, when i checked the resistance earlier on 400k ohm i got nothing but on 200k ohms i got a reading.I know this is a stupid question but never hurts to learn more

  2. #2
    Join Date
    Nov 2001
    Posts
    1,874
    Ohm out a good and you'll have your answere.

    That will be different from a 120 to 24,
    the number of windings will be different.
    If you try to fail, and succeed.
    Which have you done ?



  3. #3
    Join Date
    Oct 2004
    Posts
    3,400
    Why would anybody care what the resistance is?

    Voltage in + no voltage out = bad transformer.

    Keep it simple.

    Be sure you find the short before you leave it.

  4. #4
    Join Date
    Nov 2001
    Posts
    1,874
    Originally posted by Wild Leg


    Be sure you find the short before you leave it.

    They don't always have shorts,
    Some just break down and burn up.
    If you try to fail, and succeed.
    Which have you done ?



  5. #5
    Join Date
    Mar 2006
    Location
    Florida, jacksonville
    Posts
    94
    I don't know i guess i was bored!

  6. #6
    Join Date
    Nov 2001
    Posts
    1,874
    Stay in the field long enough you'll find plenty to rattle the brain
    If you try to fail, and succeed.
    Which have you done ?



  7. #7
    Join Date
    Apr 2004
    Posts
    7,680
    Odds are you are looking at the secondary with your ohm meter for the failure. Better odds suggest that you look at the high voltage side since it is likely the turns that are open.

  8. #8
    Join Date
    Sep 2006
    Posts
    91
    If V=IR
    Your V is 26v You I for a 40Va is 40Va / 26V ~ 1.5a

    Then 26v / 1.5a ~ 17 ohms?

    Now I gotta go check...

  9. #9
    Join Date
    Sep 2006
    Posts
    91
    Originally posted by stafford
    If V=IR
    Your V is 26v You I for a 40Va is 40Va / 26V ~ 1.5a

    Then 26v / 1.5a ~ 17 ohms?

    Now I gotta go check...

    I measured 1.1 on the secondary, 56 on the 230v primary

    Always knew that Ohm guy was full of crap.
    Man I need a service call

  10. #10
    Join Date
    Jun 2003
    Location
    Florida
    Posts
    9,548
    Only reason to know is if wires are un-indentifiable....
    If everything was always done "by the book"....the book would never change.

  11. #11
    Odds are, the leads on your meter are intermittant or you have some other measurement issue or operator error.

    Stafford:

    Learn the diffeence between impedance and resistance.

    [Edited by keepitsimplestupid on 11-02-2006 at 08:23 PM]

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