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Question
Electrical energy is transmitted over large distances at high alternating voltages. Which of the following statements is (are) correct?
- For a given power level, there is a lower current.
- Lower current implies less power loss.
- Transmission lines can be made thinner.
- It is easy to reduce the voltage at the receiving end using step-down transformers.
Options
a, b and c
a, b and d
b, c and d
c and d
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Solution
a, b and d
Explanation:
As we know that power = `I_(rms)^2R`
So to decrease power loss Irms and R must be lower for a constant power supply. To decrease Irms, Vrms must be increased by step up transformer to get same power in step-up transformer
For a given power level, we find that
P = ErmsIrms ......(Irms is low when Erms is high)
Power loss = `I_(rms)^2` R = low ......(∵ Irms is low)
Now at the receiving end, high voltage is reduced by using step-down transformers.
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