Can someone please help with this physics question? Thank You! A large power pla

Question

Can someone please help with this physics question? Thank You!

A large power plant generates electricity at 12.0 kV. Its old transformer once converted the voltage to 390 kV. The secondary of this transformer is being replaced so that its output can be 508 kV for more efficient cross-country transmission on upgraded transmission lines. (a) What is the ratio of turns in the new secondary to turns in the old secondary? (b) What is the ratio of new current output to old output (at 390 kV) for the same power? (c) If the upgraded transmission lines have the same resistance, what is the ratio of new line power loss to old?

Explanation / Answer

Here ,

as only the secondary coil of the transformer is changed

as Vs,new/Vs,old = Ns,new/Ns,old

508/390 = Ns,new/Ns,old

Ns,new/Ns,old = 1.303

b)

as Power = V*I

Is,new * Vs*new = Is,old * Vs,old

Is,new/Is,old = Vs,old/Vs,new

Is,new/Is,old = 390/508

Is,new/Is,old =0.768

c)

FOr same resistance ,

P = I^2 * R

Pnew/Pold = = (Is,new/Is,old)^2

Pnew/Pold = (0.768)^2

Pnew/Pold =0.59

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