scope:

This part of IEC 61558 deals with safety aspects of control transformers and power supplies incorporating control transformers such as electrical, thermal and mechanical safety. This Part 2-2 is applicable to control transformers and power supplies incorporating both control transformers and electronic circuits. This Part 2-2 is not applicable to external circuits and their components intended to be connected to the input terminals, output terminals or socket-outlets of the transformer and power supplies. This Part 2-2 does not apply to transformers covered by IEC 60076-11. This Part 2-2 applies to stationary or portable, single-phase or poly-phase, air-cooled (natural or forced), independent or associated control transformers and power supplies incorporating a control transformer, having a rated supply voltage not exceeding 1 000 V a.c. and rated supply and internal operating frequency not exceeding 500 Hz. The rated thermal output does not exceed: - 25 kVA for single-phase control transformers and power supplies incorporating control transformers; - 40 kVA for poly-phase control transformers and power supplies incorporating control transformers. This Part 2-2 is applicable to control transformers and power supplies incorporating control transformers without limitation of the rated output subject to an agreement between the purchaser and the manufacturer. This Part 2-2 is applicable to dry-type transformers. The windings may be encapsulated or non-encapsulated. The no-load output voltage or the rated output voltage does not exceed 1 000 V a.c. or 1 415 V ripple-free d.c. For independent control transformers and independent power supplies incorporating control transformers, the no-load output voltage and / or the rated output voltage is not less than 50 V a.c., or 120 V ripple free d.c.