Overview

A generator set consists of an engine driver and an electrical dynamo known as an alternator or generator. The prime mover delivers the mechanical power to generate the electricity, and the dynamo creates the voltamperes of electrical apparent power. Ignoring inefficiencies or losses, the kilowatt output of the dynamo is equal to the kilowatt power capability of the prime mover, the engine. On the other hand, the power factor of the load may cause the kilovoltampere flow to greatly exceed the numeric value of kilowatts. Accordingly, the kilowatt rating of a generator set is limited by the output of the engine, whereas the kilovoltampere rating of the generator set is limited by the electric current output of the dynamo connected to the engine.

Engine horsepower output is determined by the burning of fuel and air and is almost always power limited by air. The larger the number of pounds of air the engine can take in over a certain time interval, the more oxygen is available to burn the fuel, and the more power the engine can produce. Air is heavier and contains more oxygen molecules when it is cold and when its pressure is high. Therefore, an engine operating on a cold day at sea level can produce more horsepower than an engine operating on a warm day on a mountaintop. It is little wonder that engine manufacturers go to great lengths to provide the largest "charges" of air possible for their engines. In gas-turbine engines...