GCSE Science | National Grid

National grid

• electrical power is transferred at high voltages from power stations, and then transferred at lower voltages in each locality for domestic use

Step-up transformers

• increases the voltage
• this allows the cables to have a low current (because P = IV)
• this is better than a high current because there is less heat energy is wasted

Step-down transformers

• decreases the voltage from power lines for safe household use

Frequency and voltage of domestic power supply

• 50 Hz
• 230 V
• AC

Direct current

• constant amount, flows the same direction.

Alternating current

• constantly changes direction

Wires

• earth wire: safety wire (O V)
• live wire: carries the potential difference (230 V)
• neutral wire: completes the circuit

Electric shocks