Full Description

This part of IEC 61558 deals with the safety of separating transformers with high insulation level and separating transformers with output voltages exceeding 1 000 V. Transformers 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 covers separating transformers with high insulation level and separating transformers with output voltages exceeding 1 000 V AC or 1 500 V DC.

This document is applicable to stationary or portable, single-phase or polyphase, air-cooled (natural or forced) independent or associated dry-type transformers. The windings can be encapsulated or non-encapsulated.

For power supply units (linear) this document is applicable. For switch mode power supply units, IEC 61558-2-16 is applicable together with this document. Where two requirements are in conflict, the most severe takes precedence.

The rated supply voltage does not exceed 1 000 V AC, and the rated supply frequency and the internal operating frequencies do not exceed 500 Hz.

The rated output does not exceed:
– 25 kVA for single-phase transformers;
– 40 kVA for polyphase transformers.

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

Where applicable the no-load output voltage or the rated output voltage:
– does not exceed 1 000 V AC or 1 500 V DC for separating transformers with high insulation level;
– does exceed 1 000 V AC or 1 500 V DC and does not exceed 15 000 V AC or 15 000 V DC for separating transformers with output voltage exceeding 1 000 V.

This document does not apply to:
– transformers covered by IEC 60076-11;
– neon transformers covered by IEC 61050; and
– power supplies and converters for use with or in products according to IEC 61347-2-10.

This document is not applicable to external circuits and their components intended to be connected to the input terminals and output terminals of the transformers.

NOTE 2 Transformers covered by this document are used only in applications where double or reinforced insulation between circuits is not required by the installation rules or by the end product standard.

NOTE 3 Normally, the transformers are intended to be used with equipment to provide voltages different from the supply voltage for the functional requirements of the equipment.

The protection against electric shock can be provided (or completed) by other features of the equipment, such as the body. Parts of output circuits can be connected to the input circuits or to protective earthing.

This document is applicable to transformers associated with specific equipment, to the extent decided upon by the relevant IEC technical committees.

Attention is drawn to the following if necessary:
– for transformers 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 transformers;
– additional requirements in accordance with other appropriate standards and national rules can be applicable to transformers intended for use in special environments.

It is possible that future technological development of transformers will require an increase in the upper limit of the frequencies. Until then this document can 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.