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XFMR test question - wye-delta TTR

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    XFMR test question - wye-delta TTR

    A wye-delta transformer has a primary line voltage of 7200 V and a secondary line voltage of 480 V. What is the turns ratio?
    Your Answer: 15:1

    Not sure what I did wrong on this question. They are both line voltages so I thought it was a simple division question.

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    Quote Originally Posted by dbryce89 View Post
    A wye-delta transformer has a primary line voltage of 7200 V and a secondary line voltage of 480 V. What is the turns ratio?
    Your Answer: 15:1

    Not sure what I did wrong on this question. They are both line voltages so I thought it was a simple division question.

    It is not a simple division. You have to pay attention to the Wye and Delta. Any winding that is Wye, you have to use phase to ground voltage. 7200/1.732. Delta windings use phase to phase.

    7200/1.732= 4160ish / 480 = ?

    Sorry Iím doing the math in my head and on my cell phone.

    Hope this helps

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    Quote Originally Posted by dbryce89 View Post
    A wye-delta transformer has a primary line voltage of 7200 V and a secondary line voltage of 480 V. What is the turns ratio?
    Your Answer: 15:1

    Not sure what I did wrong on this question. They are both line voltages so I thought it was a simple division question.
    I did the same thing. Is the first reply right? Anyone?

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    Quote Originally Posted by JtotheJ View Post
    I did the same thing. Is the first reply right? Anyone?
    First reply is correct. 4160/480=8.66667

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    Quote Originally Posted by ElectricalTestTech View Post
    It is not a simple division. You have to pay attention to the Wye and Delta. Any winding that is Wye, you have to use phase to ground voltage. 7200/1.732. Delta windings use phase to phase.

    7200/1.732= 4160ish / 480 = ?

    Sorry Iím doing the math in my head and on my cell phone.

    Hope this helps
    Thank you that cleared up this question for me.

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