High Voltage Transmission Flashcards

All 5 cards in this deck

Why is electrical power transmitted at high potential difference?

For a given power, $P = I \times V$ means the current is small, and $P = I^2 \times R$ means less energy is wasted as heat in the cables.

Which equation gives the power wasted as heat in a transmission cable?

$P = I^2 \times R$, where $I$ is the current and $R$ the resistance of the cable.

True or false? Doubling the current in a transmission line doubles the power wasted as heat.

False. Power wasted is proportional to $I^2$, so it becomes four times greater.

What are the steps to calculate the power wasted as heat in a transmission cable?

e.g. current 20 A, cable resistance 5 $\Omega$

1. Use $P = I^2 \times R$.
2. Substitute: $P = 20^2 \times 5$
3. $P = 2000$ W

For the same power transmitted, what happens to the current when the potential difference is stepped up ten times?

The current becomes ten times smaller, because $P = I \times V$.