Electric Generator
An electric generator is defined as a mechanical device that converts kinetic energy into electrical energy, utilizing a magnetic field. This process is based on the principle of electromagnetic induction, which is the fundamental mechanism behind the generation of induced current. The manufacturing of electric generators has significantly advanced, particularly in the ability to create high-efficiency rectified current. The electrical current generated is directed to flow through an external electrical circuit. Various sources can power electric generators, including synchronous motors, steam turbine systems, hydroelectric water flow, known as hydropower (such as wind turbines), and compressed air, among others.
Electric energy can be converted back into mechanical energy through an electric motor. Electric motors can also be mechanically driven to generate electricity. The Latin term for an electric generator is “dynamo,” which refers to a device that produces a continuous current using a current inverter. The first electric generator was invented by the English scientist Michael Faraday in 1831.
Principle of Operation of Electric Generators
Electricity is generated when a coil (a metallic wire wound to produce electromagnetic induction, allowing current to travel great distances in small areas and generating a strong magnetic field) rotates within a magnetic field. This mechanical energy rotation results in electrical energy (electromagnetic induction). For example, a bicycle lamp relies on the wheel’s motion to generate electricity to illuminate the lamp. In electricity generation plants, renewable energy sources such as air or water are utilized, where the movement of turbines converts water flow into electricity.
This means that when the rotor (the rotating part) is turned by a rotor shaft connected to a prime mover, an electromagnetic field is generated. This field is transferred to the coils in the stator (the stationary part), which receives the electromagnetic field and converts it into electrical current through coils distributed over three phases, with an angle of 120 degrees between each phase. The output is a steady electrical current in the form of sine waves.
Components of an Electric Generator
Every electric generator consists of two main components:
- Mechanical Component: It includes a stationary element (fixed within the machine) and a rotating element (the rotor that spins within the machine).
- Electrical Component: This comprises the following:
- Supporting Frame: This part generates power within the electrical machine, as its coils produce electrical energy and can be mounted on either the rotor or the stator.
- Field Windings: This component creates the magnetic field in the electrical machine, utilizing a permanent magnet that is fixed onto either the rotor or the stator of the mechanical part.
Types of Electric Generators
Based on their function, generators can be categorized into:
- Main Generator: This is the primary generator that the grid entirely relies upon for electric power production.
- Backup Generator: This serves as a substitute in case the main generator fails.