Generators

Generators are machines that convert mechanical energy into electrical energy. They operate on electromagnetic induction: when a conductor experiences a changing magnetic flux, an electric current is induced. In power-generation contexts, generators are driven by a prime mover such as a turbine or engine to supply electrical energy for grids, buildings, or equipment.

Most electrical generators are alternating current (AC) machines, known as alternators. Direct current (DC) generators, once common, are now largely supplanted by AC designs in most applications. An AC generator typically comprises a rotor (the rotating part) and a stator (the stationary part). As the rotor is driven by a prime mover, magnetic field interacts with the stator windings to produce voltage. The frequency of the output is determined by rotation speed and the number of rotor poles.

A generator’s performance is governed by its excitation system and control strategy. In synchronous generators, the rotor receives a controlled DC current to establish the magnetic field, enabling voltage regulation through the automatic voltage regulator. Induction generators rely on slip between rotor and stator fields and are often used with grid support or capacitive networks. Efficiency and reliability depend on design, cooling, load, and control systems, with modern units optimized for improved regulation and reduced emissions.

Applications include large central power plants, distributed generation, and portable or standby units for homes and businesses. Ratings are expressed in kilowatts or kilovolt-amperes. Generators are selected by anticipated load, reliability requirements, and fuel type (diesel, natural gas, hydro, or steam). In grid applications, synchronization and protections are essential for safe, stable operation.