EVS-EN 61558-2-6:2001

This part 2 of IEC 61558 applies to stationary or portable, single-phase or polyphase, air-cooled safety isolating transformers, associated or otherwise, having a rated supply voltage not exceeding 1000 V a.c. and rated frequency not exceeding 500 Hz, the rated output not exceeding 10 kVA for single-phase transformers and 16 kVA for polyphase transformers.
This standard is also applicable to safety isolating transformers without limitation of the rated output; however such transformers are considered as special transformers and are subjected to an agreement between the purchaser and the supplier.
The no-load output voltage and the rated output voltage does not exceed 50 V a.c. r.m.s. and/or 120 V ripple-free d.c. between conductors or between any conductor and earth.
This standard is applicable to dry type transformers. The windings may be capsulated or non-encapsulated.