Transformers & the National Grid Flashcards

All 8 cards in this deck

List the parts of the national grid in the order electricity passes through them.

Power station → step-up transformer → transmission lines → step-down transformer → consumer.

Why is electrical energy transferred at high voltage in the national grid's transmission lines?

Heat loss is reduced, so transmission is more efficient.

True or false? A step-up transformer in the national grid increases both the potential difference and the current.

False. It increases the potential difference and decreases the current.

Why is a step-down transformer used in each locality before electricity reaches homes?

It reduces the potential difference to a lower, safer voltage for domestic use.

What is the power equation for a transformer with 100% efficiency?

$V_p \times I_p = V_s \times I_s$ — the power input to the primary equals the power output from the secondary.

How can you tell from the potential differences whether a transformer is step-up or step-down?

e.g. $V_p = 12$ V, $V_s = 240$ V

Step-up if $V_s$ is greater than $V_p$; step-down if $V_s$ is smaller.

e.g. 240 V > 12 V, so it is step-up.

What are the two coils in a transformer called?

The primary coil and the secondary coil. The primary coil is the input side, the secondary coil is the output side.

In the national grid, why does a lower current in the transmission lines mean less energy is wasted?

A current heats the cables, so a smaller current heats them less and less energy is lost to the surroundings.