This standard defines the terms that appear when a reciprocating internal combustion (RIC) engine and an alternating current (ac) generator are used as a unit and specifies the design criteria. This standard applies to ac generating sets powered by RIC engines for land and marine use, and does not apply to generating sets for aviation or for driving land vehicles and locomotives. For some special purposes (such as necessary hospital power supply, high-rise buildings, etc.), additional requirements may be necessary, and the provisions of this standard should be used as the basis. For generator sets driven by other types of reciprocating prime movers (eg biogas engines, steam engines), the provisions of this standard can be used as a basis.