Elecric Generator

The reverse conversion of electrical energy into mechanical energy is done by an electric motor, and motors and generators have many similarities. In fact many motors can be mechanically driven to generate electricity, and very frequently make acceptable generators.

In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric charge(usually carried by electrons) to flow through an external electrical circuit. It is analogous to a water pump, which causes water to flow (but does not create water). The source of mechanical energy may be a reciprocating or turbine steam engine, water falling through a turbine or waterwheel, an internal combustion engine, a wind turbine, a hand crank, compressed air or any other source of mechanical energy.

Before the connection between and was discovered, electrostatic generatorselectrostatic principles. These generated very high voltages and low currents. They operated by using moving electrically charged belts, plates and disks to carry charge to a high potential electrode. The charge was generated using either of two mechanisms:

• The triboelectric effect, where the contact between two insulators leaves them charged.

Because of their inefficiency and the difficulty of insulating machines producing very high voltages, electrostatic generators had low power ratings and were never used for generation of commercially significant quantities of electric power. The Wimshurst machine and Van de Graaff generator are examples of these machines that have survived.