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Do the same exercise as above with the replacement of the earlier transformer by a 40,000-220V 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 volage transmission is preferred ? |
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Answer» Solution :Given primary VOLTAGE `V_(P)=40,000 V` Let the current in primary is `I_(P)` `therefore V_(P)I_(P)=P` `800xx1000=40000 xx I_(P)` `I_(P)=20A` (a) Line power loss `= (I_(P))^(2)xxR` `= (20)^(2)xx2xx0.5xx15` `= 6000W = 6KW` (B) Power SUPPLY by plant `= 800+6=806KW` Voltage drop of line `= I_(P).R` `= 20xx2xx0.5xx15` = 300 V Voltage for transmission `= 40000+300=40300V` Power loss at higher voltage `= (6)/(800)xx100=0.74%` Power loss at lower voltage `= (600)/(1400)xx100=42.8%` Hence, the power loss is minimum at higher voltage. So, the high voltage transmission is preferred. |
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