SLNS BS EN 61558-1:2005

Safety of power transformers, power supply units and similar-Part 1: General requirements

Scope

This International Standard deals with safety aspects of power transformers, power
supplies, reactors and similar products such as electrical, thermal and mechanical safety.
This standard covers the following types of dry-type transformers, power supplies,
including switch mode power supplies, and reactors, the windings of which may be
encapsulated or non-encapsulated :
NOTE 1 The distinction between transformers, power supplies and switch mode power supplies is as follows:
– for transformers, there is no change in frequency .However, transformers (e.g. constant voltage
transformers) may have an internal resonance frequency not exceeding 30 kHz;
– for power supplies, the internal operational frequency and waveform are different from the supply
frequency and waveform, and the internal operational frequency does not exceed 500 Hz (see definition
3.1.19);
– for switch mode power supplies, the internal operational frequency and waveform are different from the
supply frequency and waveform and the internal operational frequency exceeds 500 Hz and does not
exceed 100 MHz.