Frequency Converters convert incoming AC Power into rotary mechanical power , which transmits its rotary power to a generator, which converts its mechanical power into Electric AC output power. Rotary power is often described in terms of Horsepower, while Electrical power is described in Kilowatts (kW) or Kilovolt-Amperes (KVA). The conversion of frequency (hertz – Hz), voltage, and/or phase (3 phase, 1 phase) are inherent in this process.
Motor Generator sets use several methods of coupling the drive motor to the generator. The simplest and least expensive method is belt coupled Converters that use drive belts and pulleys to not only transfer the energy from motor to generator, but also change the frequency by pulley ratio. Another method is direct coupled converters that directly couple the motor shaft to the generator shaft using a mechanical coupling, and adjusting the speed of the drive motor to vary the rotational speed of the generator, thus varying the output frequency. An adjustable speed electronic drive is used for this purpose, instead of a conventional motor starter.Finally, the most sophisticated and most costly method is to build the motor and generator onto a single common shaft, called common shaft frequency converters. In this case, the frequency change is made by winding the motor with a different number of electrical poles than the generator.
In certain applications, only power line isolation or power line conditioning , is required. In these power line isolators, an insulated flexible coupling is used between motor and generator, to transmit the power from motor to generator, and completely isolate the input from the output. Typically, no change is made to the frequencies, although phase or voltage conversion may be required.