PHYSICS · Subjective · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
A factory requires a steady supply of 5MW at 220V. The total resistance of the transmission line between the generating station and the factory is estimated to be 2Ω. The power company wishes to limit the power lost as heat in the line to not more than 1% of the power that actually reaches the factory.
(a) Show how to obtain an expression for the minimum rms transmission voltage that will satisfy this restriction when the delivered power and line resistance are fixed.
(b) Using the numerical data given, determine the minimum rms transmission voltage required at the sending end so that the stipulated loss limit is met.
(c) If the station initially transmitted the same power at only 11kV, calculate the percentage of the generated power that would have been wasted in the line.