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    3 phase transformer

    We bought a 3 phase transformer from Automation Direct that is 480vac primary with taps and 240vac secondary. When this was wired and powered up it went up in smoke. wiring diagram says to use number 1 tap on primary so it goes H1,H2,H3 all with 1 tap for 480 vac. X1,x4-2, x3 for secondary. I am confused as to why this burned up. Any ideas would be appreciated.

    #2
    Originally posted by pmoore View Post
    We bought a 3 phase transformer from Automation Direct that is 480vac primary with taps and 240vac secondary. When this was wired and powered up it went up in smoke. wiring diagram says to use number 1 tap on primary so it goes H1,H2,H3 all with 1 tap for 480 vac. X1,x4-2, x3 for secondary. I am confused as to why this burned up. Any ideas would be appreciated.
    It could have been a multitude of reasons.

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      #3
      Originally posted by pmoore View Post
      We bought a 3 phase transformer from Automation Direct that is 480vac primary with taps and 240vac secondary. When this was wired and powered up it went up in smoke. wiring diagram says to use number 1 tap on primary so it goes H1,H2,H3 all with 1 tap for 480 vac. X1,x4-2, x3 for secondary. I am confused as to why this burned up. Any ideas would be appreciated.
      You didn't get confused with what that is saying and tie X4 and X2 together did you?

      What you have there is supposed to be X1, X2, and X3 are 240 volts three phase between them. X4 is the midpoint (neutral) and is 120 volts between X1 and X2, with X3 being the high leg (208 volts to X4).

      If you misinterpreded it (probably could have been written a little differently to be more clear) and tied X2 and X4 together, you created a bolted fault on the 120 volt output from the X2 to X4.
      I live for today, I'm just a day behind.

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        #4
        Even though we had not hooked up the secondary to its source yet?

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          #5
          Originally posted by pmoore View Post
          Even though we had not hooked up the secondary to its source yet?
          The transformer secondary "X" leads is the link to the "source" for the 120/240 derived system, you probably meant to ask "even if we had not hooked up any conductors to the load yet".

          If you connected any two "X" leads together on this unit you have a fault between those two leads even if nothing else is connected on the secondary.
          I live for today, I'm just a day behind.

          Comment


            #6
            Originally posted by pmoore View Post
            We bought a 3 phase transformer from Automation Direct that is 480vac primary with taps and 240vac secondary. When this was wired and powered up it went up in smoke. wiring diagram says to use number 1 tap on primary so it goes H1,H2,H3 all with 1 tap for 480 vac. X1,x4-2, x3 for secondary. I am confused as to why this burned up. Any ideas would be appreciated.
            What actually happened? I am skeptical that a transformer just "goes up in smoke". Seems like an ocpd would have tripped.
            Ethan Brush - East West Electric. NY, WA. MA

            "You can't generalize"

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              #7
              The transformer does have a fused source on the primary and secondary and looking closer to the secondary yes our problem was in that. X1 was line one and x2 and 4 was tied together which would have caused a fault. Thanks for the information. Time to get another transformer

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