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transformers

m.weatherbee
m.weatherbee Member Posts: 8
in THE MAIN WALL
HEY GUYS GOT A TOUGH ONE. TRYING TO LOCATE A SHORT IN A ROOFTOP.PROBLEM IT ONLY HAPPEHS ONCE EVERY 30 MIN OR SO.I HAVE A 100VA TRANSFORMER THAT PULLS 2.7 AMPS WITH 4 STAGES RUNNING . IT WILL JUMP UP TO 20 AMPS THEN SHUT DOWN IS THE 2.7 RUNNING LOAD TOO MUCH?ALSO DOES ANY ON KNOW IF U PUT YOUR AMPPROBE 0N BRANCH LEGS OF A LOW VOLTAGE PARRELL CIRCUIT WILL THE HIGH AMPS ONLY READ IN THE SHORTED LEG OR WILL IT DRAW FROM ALL LEGS. ANY ADVICE I,M ABOUT TO JUMP OFF THE ROOF.

Comments

  • Alan_6
    Alan_6 Member Posts: 87


    It will only show the total amp draw in series off the transformer. Parallel will only show the load of the individual circuit. 2.7 amps off a 100va. is normal. Sounds like something is shorting after it gets warm. Goodluck, may have to replace controls one at a time.
  • jeff_25
    jeff_25 Member Posts: 110
    amps

    is this in the heating or cooling mode? is the 20 amps on the line side or the sendary side if its in the cooling mode i would look at the contactors you can install your volt amp inline to check amps also you can put on a amp clamp if its digtal that can read the smaller amp. if you have to take some 3 amp auto type fuses that are use on circiut board and some inslutated term. and fuse as many cict. as you can to find who is drawing the high 24 volt amps
  • jim lockard
    jim lockard Member Posts: 1,059
    Do like jeff

    Said break the circuit down add fuses and or parallel test lights across your coils and sequencers til you find it. Remember that a parallel electrical circuit consists of one or more switches but only one load so break it down. What size wire to the T-stat try disconnecting the t-stat wiring and install jumpers. Any timed in controls in the circuit? Sequencers? Best Wishes J.Lockard
  • Dale
    Dale Member Posts: 1,317
    Breakers

    Most roof tops have a little inline circuit breaker to protect the secondary side of that expensive 100va tfmr. I would put in line one amp breakers or glass fuses to each of your loads and fire it up again, I always suspect gas valve coils but as the other posts suggested it could be anywhere so you'll need to isolate to limit the places to look.
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