Do the same exercise as above with the replacement of the earlier transformer by a 40,000-220 V step-down transformer (Neglect, as before, leakage losses though this may not be a good assumption any longer because of the very high voltage transmission involved). Hence, explain why high voltage transmission is preferred.

Explanation

`I_(rms) = P/V = (800 xx 1000)/(40000) = 20A`
a. Line power loss `= I^2R = 20^2 xx 15 = 6 kW `
b. Power supplied = 800 + 6 = 806 kW
c. Voltage dropped = IR = 20 x 15 = 300 V
d. Step up transformer should be of 440V/40300V
Power loss `= 6/806 xx 100 = 0.74 % `
This power loss reduces a lot, if power is transmitted at high voltage.