Deals with all aspects of safety such as electrical, thermal and mechanical. This part 2-13 of IEC 61558 applies to stationary or portable, single-phase or polyphase, air-cooled (natural or forced), independent or associated auto-transformers, having a rated supply voltage not exceeding 1000 V a.c., a rated frequency not exceeding 500 Hz. This part 2-13 is intended to be used in conjunction with IEC 61558-1. This standard replaces Chapter III of IEC 60989. It has the status of a group safety publication in accordance with IEC Guide 104.