| Notes: Replacement:
This part 2 of IEC 61558 applies to associated power transformers for switch mode power supplies, single-phase 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;
- 16 kVA for polyphase transformers.
NOTE 1 – For higher frequencies, this standard may be used as a guide.
The no-load output voltage or the rated output voltage do not exceed:
– 1000 V a.c. or 1 415 V ripple-free d.c for separating transformers;
– 500 V a.c. or 708 V ripple-free d.c for isolating transformers.
NOTE 2 – For isolating transformers, the rated output voltage may be up to 1000 V a.c. or 1415 ripple-free d.c. in accordance with the national wiring rules or designed for special purposes.
– 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.
NOTES 3 For transformers filled with liquid dielectric or pulverized material, such as sand, additional requirements are under consideration.
4 In locations where special environmental conditions prevail, particular requirements may be necessary in accordance with IEC 364-5-51.
5 For higher output no-load voltages, additional requirements are necessary but this section may be used as a guide. | 
