This part 2 of IEC 61558 applies to associated power transformers for switch mode power supplies, single-pahse or polyphase, air-cooled: - separating transformers; - isolating transformers; - safety isolating transformers, having a rated supply voltage not exceeding 1000 V a.c. and a rated frequency of 500 Hz to 1 MHz, the rated output not exceeding: - 10 kVA for single-phase transformers and 16 kVA for polyphase transformers. The no-load output voltage or the rated output voltage do not exceed 1000 V a.c. or 1415 V ripple-free d.c. for separating transformers; 500 V a.c. for 708 V ripple-free d.c. for isolating transformers and 50 V a.c. r.m.s. and/or 120 V ripple-free d.c. for safety isolating transformers. This standard is applicable to dry type transformers. The windings may be encapsulated or non-encapsulated.