IEC 60034-22:2009 establishes the principal characteristics of a.c. generators under the control of their voltage regulators when used for reciprocating internal combustion engine driven generating set applications and supplements the requirements given in IEC 60034-1. It covers the use of such generators for land and marine use, but excludes generating sets used on aircraft or used to propel land vehicles and locomotives. The most important changes with respect to the previous edition are: - technical changes to many definitions; - revision of table 1 and of the annex.