In high voltage power transmission, electricity is transmitted at a high voltage so that. according to P=VI, the current will decrease greatly. Then according to P=I^2R, the power loss can be greatly reduced. However, if we use P=V^2/R instead, then the use of high voltage will lead to great power loss.
Is this correct? Or is that the power in the two cases actually representing different things? Why it seems that the application of these two equations are contradicting?
I have read the reply in some other similar questions, but I am still confused about it. So, please give me answers different from those reply=]
THZ=]
high voltage transmission
2012-04-13 4:35 am
回答 (2)
2012-04-13 7:39 am
✔ 最佳答案
Whichever equation you use, you would get the same result.According to the equation P =(Vs).I, for a given power output P, rasising the supplied voltage Vs will decrease the current I.
A reduced current would therefore cause less power to be consumed (or wasted) during tansmission on a cable with resistance R, as according to the equation P(loss) = I^2.R.
As the current is reduced, the potential drop Vc across the transmission cable would also reduce accordingly by Ohm's Law ( Vc = I.R). As such, the power loss on the cable is consequently decreased using the formula P(loss) = Vc^2/R.
2012-04-13 6:06 am
power lost純粹係電流通過r產生電壓降做成，係相同r之下電流愈大降壓愈大，如果p=vi係計算power lost嘅公式，咁與閣下所講其餘兩條公式其實相同，但r應該係導線電阻，而並非負載(loading)電阻。
收錄日期: 2021-04-23 21:22:00
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20120412000051KK01005