Generators and alternators
Machines that turn rotation into electricity in almost every power plant.
Conversion and use · Conversion devices · No. 99
- Conversion and use
The world's biggest generator turns 99% of its spin into electricity, yet still sheds enough heat to warm thousands of homes.
Chart: Illustration: Generators and alternators
Where it comes from
Chart: Map of where it comes from
Moving a magnetic field past copper coils induces a voltage, Faraday's law, which every coal, gas, nuclear and most hydro plant relies on.
Three things to know
- Generators are not heat engines, so no Carnot limit applies; losses are only resistance, magnetic and friction effects.
- Very large units are cooled with hydrogen, about one fourteenth as dense as air (calculated), to cut drag and carry heat away.
- Each 0.1 point of efficiency on a big unit is worth about USD 0.4 million a year (calculated).
The journey
- 1 TurbineSteam, gas, water or wind spins
- 2 RotorSpinning electromagnet carries the field
- 3 StatorCopper coils feel a changing field
- 4 InductionVoltage appears, 18-27 kV at terminals
- 5 GridTransformers step it up for transmission