This part 2 of IEC 61558 is intended to be used in conjunction with IEC 61558-1. This international standard deals with all aspects of safety such as electrical, thermal and mechanical. This part of IEC 61558 applies to stationary or portable, single-phase or polyphase, air-cooled (natural or forced), associated or independent: - constant voltage auto-transformers; - constant voltage separating transformers; - constant voltage isolating transformers; - constant voltage safety isolating transformers; having a rated supply voltage not exceeding 1 000 V a.c., a rated frequency not exceeding 500 Hz, an internal operational frequency not exceeding 30 kHz and no limitation of the rated output. It has the status of a group safety publication in accordance with IEC Guide 104