It specifies the maximum permissible sound power levels for rotating electrical machines (such as motors and generators) under specific conditions. Its primary purpose is to ensure that industrial equipment does not exceed noise thresholds that could be harmful to workers or the environment. Why You Should Avoid "Free Download" Sites
Several countries adopt IEC 60034-9 verbatim as their national standard and may release it for free or low cost. Examples: iec 60034-9 pdf free download