The National Grid
I can describe the National Grid and explain why transmission lines use a very high transmission voltage.
The National Grid
I can describe the National Grid and explain why transmission lines use a very high transmission voltage.
Lesson details
Key learning points
- Power is transferred by electricity from power stations to consumers using the National Grid.
- Step-up transformers increase the transmission voltage from a power station to the transmission line.
- Step-down transformers decrease the transmission voltage from a transmission line to the consumer.
- Transmission lines dissipate some energy by heating (P = I²R).
- A very high transmission voltage reduces transmission current and the heating of transmission lines.
Common misconception
The voltage (drop) across power lines is the same as the voltage they transmit.
Spend time to clarify that the power transmitted depends on the p.d. between the live and neutral wires, and power dissipated depends on the drop in voltage from one end of a live wire to the other.
Keywords
National Grid - a high voltage transmission system for getting electricity to where it is needed
Transmission line - a high voltage cable often seen between electricity pylons
Step-up transformer - a device that can change lower alternating voltages to higher ones
Step-down transformer - a device that can change higher alternating voltages to lower ones
Dissipation - the transfer of energy into the surroundings by heating
Equipment
Power line demonstration kit - but only for fully trained and experienced teachers!
Licence
This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
Video
Loading...