ISO 8528-9:2017 describes a procedure for measuring and evaluating the external mechanical vibration behaviour of generating sets at the measuring points stated in this document. It applies to RIC engine driven a.c. generating sets for fixed and mobile installations with rigid and/or resilient mountings. It is applicable for land and marine use, excluding generating sets used on aircraft or those used to propel land vehicles and locomotives. For some specific applications (essential hospital supplies, high rise buildings, etc.) supplementary requirements may be necessary. The provisions of this document are intended to be regarded as a basis for such applications. For generating sets driven by other reciprocating-type prime movers (e.g. sewage gas engines, steam engines), the provisions of this document are intended to be regarded as a basis for such applications.