Answer to Question #117580 in Electric Circuits for Ben

Question

Describe how AC electricity is transferred from the hydroelectric plant to homes and industry. Mathematically account for the need of transformers and high voltages. You should include:

Answer 1

The attached image below shows how the electricity is transferred from hydroelectric plant to homes and industries

• In power stations, large spinning turbines generate electricity, powered by wind, coal, natural gas, or water (hydropower).
• The electrical current is sent through transformers, which increase the voltage so the power can be pushed over long distances.
• The electrical charge is then carried by transmission lines held up by large towers, which stretch across huge distances.
• From the transmission lines, the electricity reaches a substation, where the voltage is lowered so it can be sent on smaller power lines.
• The electricity is then sent through distribution lines to your neighbourhood. Smaller transformers lower the voltage again so that the power is safe to use in our homes.
• The electricity connects to your house, where it passes through a meter which measures the amount of electricity you use.
• Finally, the electricity travels through wires inside the walls to the outlets and switches in your house - ready to power your devices!

The need for transformers and high voltages is determined by losses in the transmission system. If you calculate that the losses are too great at low voltage, but can calculate that the losses are lower by using a transformer and a higher voltage, then that is how you account for need.

Cost is also a factor.

Consider a short term hookup over, say, 500m to a kilometer at 240v where you know your losses may be 10%. You may only need the hookup for a very short term (a few weeks for temporary power during construction, for example). You know that you will use x kWh of energy, and lose 10% of that in losses over the distance.

OK, you might want to consider a transformer at each end of the link and step up to 11kV, and then back down to 240v at the other end. Now you have perhaps reduced your losses to 1 or 2%