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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. |
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Answer» Solution :`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. |
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