IEC 61558-2-20 Ed. 3.0 b:2022

This part of IEC 61558 deals with the safety of small reactors for general applications. Small reactors incorporating electronic circuits are also covered by this document.

NOTE 1 Safety includes electrical, thermal and mechanical aspects.

Unless otherwise specified, from here onward, the term transformer or reactor covers small reactors.

This document is applicable to stationary or portable, single-phase or polyphase, air-cooled (natural or forced) general purpose reactors including alternating current, premagnetised and current compensated independent or associated dry-type reactors. The windings can be encapsulated or non-encapsulated.

The rated supply voltage does not exceed 1 000 V AC or 1 500 V ripple-free DC, the rated supply frequency and the internal operating frequencies do not exceed 100 MHz.

This document can be used for reactors with a fundamental frequency above 500 Hz (see Annex BB). 

The rated power does not exceed:
– 25 kVAR AC (25 kW DC) for single-phase reactors,
– 50 kVAR AC (50 kW DC) for poly-phase reactors.

This document is applicable to reactors without limitation of the rated power subject to an agreement between the purchaser and the manufacturer.

This document does not apply to:
– reactors covered by IEC 60076-6 for rated voltages above 1 000 V;
– ballast for tubular fluorescent covered by IEC 61347-2-8;
– ballast for discharge lamps (excluding tubular fluorescent lamps) covered by IEC 61347‑2‑9.
– fixed inductors for electromagnetic interference suppression covered by IEC 60938 series

NOTE 2 For reactors filled with liquid dielectric or pulverised material such as sand, additional requirements are under consideration.

NOTE 3 Normally, reactors are intended to be associated with equipment for functional requirements of the equipment or requirements by the installation rules or by other appliance specifications. The protection against electric shock may be provided or completed by other parts or features of the equipment, such as the body.

NOTE 4 Reactors for particular applications will in the future be covered by complementary normative annexes.

Attention is drawn to the following if necessary:
– for reactors intended to be used in vehicles, on board ships, and aircraft, additional requirements (from other applicable standards, national rules, etc.);
– measures to protect the enclosure and the components inside the enclosure against external influences such as fungus, vermin, termites, solar-radiation, and icing;
– the different conditions for transportation, storage, and operation of the reactors;
– additional requirements in accordance with other appropriate standards and national rules may be applicable to reactors intended for use in special environments.

Future technological development of reactors may necessitate a need to increase the upper limit of the frequencies. Until then, this document may be used as a guidance document.

This group safety publication focusing on safety guidance is primarily intended to be used as a product safety standard for the products mentioned in the scope, but is also intended to be used by technical committees in the preparation of publications for products similar to those mentioned in the scope of this group safety publication, in accordance with the principles laid down in IEC Guide 104 and lSO/lEC Guide 51.

One of the responsibilities of a technical committee is, wherever applicable, to make use of basic safety publications and/or group safety publications in the preparation of its publications.