A diesel generator is the combination of a diesel engine with an electrical generator (often called an alternator) to generate electric energy. Diesel generating sets are used in places without connection to the power grid or as emergency power-supply if the grid fails. Small portable diesel generators range from about 1 kVA to 10 kVA may be used as power supplies on construction sites, or as auxiliary power for vehicles such as mobile homes.
The packaged combination of a diesel engine, a generator and various ancillary devices such as base, canopy, sound attenuation, control systems, circuit breakers, jacket water heaters, starting systems etc, is referred to as a generating set or a gen set for short.
While the larger industrial diesel generators and generator sets can range from 8 to 30 kVA for homes, small shops & offices up to 2,000 kVA used for large office complexes, factories. A 2,000 kVA set can be housed in a
Diesel generators, sometimes as small as 250 kVA are widely used not only for emergency power, but also many have a secondary function of feeding power to utility grids either during peak periods, or periods when there is a shortage of large power generators.
Generating sets are selected based on the load they are intended to supply power for, taking into account the type of load, ie emergency or for continuous power, and the size of the load, and size of any motors to be started which is normally the critical parameter.