This part of IEC 61558 deals with the safety of small reactors for general applications. NOTE 1 Safety includes electrical, thermal and mechanical aspects. Unless otherwise specified, from here onward, the term transformer or reactor covers small reactors. This Part 2-20 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 reactors. The rated supply voltage does not exceed 1 100 V a.c. or 1 555V ripple-free d.c., the rated supply frequency and the internal operating frequencies do not exceed 1 MHz. The rated power does not exceed: - 25 kVAR a.c. (25 kW d.c.) for single-phase reactors - 50 kVAR a.c. (50 kW d.c.) for poly-phase reactors This Part 2-20 is applicable to reactors without limitations of the rated power subject to an agreement between the purchaser and the manufacturer. This Part 2-20 is applicable to dry-type reactors. The windings may be encapsulated or nonencapsulated. This Part 2-20 does not apply to: - reactors covered by IEC 60289; - ballast for tubular fluorescent lamps covered by IEC 60920; and - ballast for discharge lamps (excluding tubular fluorescent lamps) covered by IEC 60922. NOTE 2 For reactors filled with liquid dielectric or pulverised material such as sand, additional requirements are under consideration. NOTE 3 Attention is drawn to the following: - for reactors intended to be used in vehicles, on board ships, and aircraft, additional requirements (from other applicable standards, national rules, etc.) may be necessary; - measures to protect the enclosure and the components inside the enclosure against external influences such as fungus, vermin, termites, solar-radiation, and icing should also be considered; - the different conditions for transportation, storage, and operation of the reactor should also be considered; - additional requirements in accordance with other appropriate standards and national rules may be applicable to reactors intended for use in special environments, such as tropical environment. NOTE 4 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. NOTE 5 reactors incorporating electronic circuits and components are also covered by this standard. NOTE 6 The protection against electric shock may be provided (or completed) by other parts or features of the equipment, such as the body. NOTE 7 Reactors for particular applications will in the future be covered by complementary normative annexes. NOTE 8 Future technological development of reactors may necessitate a need to increase the upper limit of the frequencies, until then this Part 2-20 may be used as a guidance document.