scope:

This part 2-2 of IEC 61558 applies to stationary or portable, single-phase or poly-phases, air-cooled control transformers associated or otherwise having a rated supply voltage not exceeding 1 000 V a.c. or 1 415 V ripple free d.c. and rated frequency not exceeding 500 Hz and no limitation of the rated output. This standard is applicable to transformers used between circuits where double or reinforced insulation is not required by the installation rules or by the equipment specification. This standard is applicable to dry type transformers. The windings may be encapsulated or non-encapsulated.