How much is the current flowing in the transmission line?

[golriz]

Asmall power plant produces a voltage of 6.0kV and a current of 150A. The voltage is stepped up to 240kV by a transformer before being sent to a substation. The resistance of the transmission line between the power plant and the substation is 75 ohm. How much is the current flowing in the transmission line?


I(p)/I(s)= V(s)/V(p) s= stationary P= primary
V= IR


I(p) = 150 , V(p) = 6.0kV , V(s) = 240kV , I(s) = ?

 

[Redbelly98]

I(p)/I(s)= V(s)/V(p) s= stationary P= primary

I(p) = 150 , V(p) = 6.0kV , V(s) = 240kV , I(s) = ?

Plug in the numbers and solve. V = IR is not needed here.

 

[golriz]

oh, why?
I don't know why V = IR is not needed here?

 

[Redbelly98]

It occurred to me (after discussing this with somebody else) that I may not understand the layout here.

Perhaps you have a figure you can look at to answer this question: is the 75 ohm line in between the power plant and the transformer, or is it between the transformer and the substation?

 

[golriz]

I think it is between the transformer and the substation.

 

[Redbelly98]

In that case, the 75Ω will affect the voltage at the substation, but not at the transformer. It is irrelevant here.

I'm not sure why they included that information, maybe just to throw you off?