Generators are devices that convert electrical energy into ordinary power using the principle of electromagnetic induction. Primary energy sources may be steam turbine engines, water turbines, internal combustion engines, wind turbines or other power sources. The first generator to be invented in 1831 was the Faraday disk, by British scientist Michael Faraday.

To convert power back to power, people use electric motors. Generators and electric motors have many of the same characteristics, so some engines can turn into generators to generate electricity.

Generators play a key role in power supply equipment. It performs three functions: power generation, rectifier, voltage correction.