scope:

This part of IEC 61558 deals with the safety of transformers for construction sites and power supply units incorporating transformers for construction sites. Transformers incorporating electronic circuits are also covered by this standard. Unless otherwise specified, from here onward, the term transformer covers transformers for construction sites and power supply units incorporating transformers for construction sites. This part is applicable to stationary or portable, single-phase or polyphase, air-cooled (natural or forced) independent or associated transformers, being isolating or safety isolating drytype transformers for the use on construction sites. The windings may be encapsulated or non-encapsulated. The rated supply voltage does not exceed 1 000 V a.c., and the rated supply frequency and the internal operating frequencies do not exceed 500 Hz. This standard used in combination with Part 2-16 for Switch mode power supply units (SMPS) is also applicable to power supplies with internal operating frequencies higher than 500 Hz. Where the two requirements are in conflict the most severe take precedence The rated output does not exceed: - 25 kVA for single-phase transformers; - 40 kVA for poly-phase transformers. This part is applicable to transformers without limitation of the rated output subject to an agreement between the purchaser and the manufacturer. Isolating transformers and power supply units incorporating isolating transformers for construction sites have a no-load output voltage and a rated output voltage exceeding 50 V a.c. and not exceeding 250 V a.c. Safety isolating transformers and power supply units incorporating safety isolating transformers for construction sites have a no-load output voltage and a rated output voltage not exceeding 50 V a.c. Transformers and power supply units covered by this part are used in applications where it is required by the installation rules or by the appliance specification for protection purposes. When the transformers or power supply units are incorporated into low voltage switchgear and controlgear assemblies for construction sites as specified in IEC 60439-4, the additional requirements of IEC 60439-4 will apply to the assembly.