3-phase transformer Y connection: voltages remain constant during ground conditions? PPI Exam 1 Question 22

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akyip

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Hey guys,

I'm a little bit confused by something that PPI exam 1 question 22 solution states as true.

PPI question 22 states to be true that in a 3-phase transformer, the Y connection ensures voltages remain constant during ground conditions. The solution then goes on to explain that an ungrounded Y connection (ungrounded at the neutral) will suffer an increase in line voltage during a ground fault. The increase in voltage would be sqrt(3) of the original value.

I'm confused. How would voltages remain constant if they increase by a factor of sqrt(3)? What is the solution trying to say?

PPI Exam 1 Q 22.jpg

PPI Exam 1 S 22.jpg

 
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