
XFMR test question  wyedelta TTR
A wyedelta 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.

Originally Posted by
dbryce89
A wyedelta 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 I’m doing the math in my head and on my cell phone.
Hope this helps

Originally Posted by
dbryce89
A wyedelta 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?

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

Originally Posted by
ElectricalTestTech
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 I’m doing the math in my head and on my cell phone.
Hope this helps
Thank you that cleared up this question for me.

Originally Posted by
dbryce89
A wyedelta 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.
divided 7200/480(square root 3)= 8.66
thats because its a 3 phase wyedelta, in a deltawye I would do in 480(square root 3)/208 in a normal commercial transformer which in fact its 4 as most of us know. correct me if I'm wrong.
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