An ac generator provides emf to a resistive load in a remote factory over a two-

Question

An ac generator provides emf to a resistive load in a remote factory over a two-cable transmission line. At the factory a step-down transformer reduces the voltage from its (rms) transmission value Vt to a much lower value that is safe and convenient for use in the factory. The transmission line resistance is R per cable, and the power of the generator is P. The generator can supply either Vt = V1 or Vt = V2. (a) What is the ratio of the voltage decrease V along the transmission line when operating at V1 to the voltage decrease at V2? (b) What is the ratio of the power loss Pd at V1 to the power loss at V2? Express your answers in terms of P, R, V1, and V2.

Explanation / Answer

for a transformer we have

V1/V2 = I2/I1

where V1 and V2 are primary and secondary voltages and I1 and I2 are corresponding currents

the power is

P1 = V1^2/R

where R is load resistance

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