BS EN 61558-2-14:2013

Safety of transformers, reactors, power supply units and combination thereof. Particular requirements and tests for variable transformers and power supply units incorporating variable transformers | Status: Current, Superseded

1 Scope Replacement: This part of IEC 61558 deals with safety of variable transformers for general applications and power supply units incorporating variable transformers for general applications. Transformers incorporating electronic circuits are also covered by this standard.

NOTE 1 Safety includes electrical, thermal, mechanical and chemical aspects.

Unless otherwise specified, from here onward, the term transformer covers variable transformers for general applications and power supply units incorporating variable transformers for general applications. The rated supply voltage does not exceed 1 000 V a.c., and the rated supply frequency does not exceed 500 Hz. This standard is applicable to transformers and power supply units (linear) with internal operational frequencies not exceeding 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 operational frequencies higher than 500 Hz. Where the two requirements are in conflict the most severe take precedence This part does not apply to transformers covered by IEC 60076‑11. This part is applicable to stationary or portable, single-phase or polyphase, air-cooled (natural or forced) independent or associated dry-type transformers.

• — variable auto-transformers and pow er supply units incorporating variable auto-transformers;
• — variable separating transformers and power supply units incorporating variable separating transformers;
• — variable isolating transformers and power supply units incorporating variable isolating transformers;
• — variable safety isolating transformers and power supply units incorporating variable safety isolating transformers.

The windings may be encapsulated or non-encapsulated. The rated output does not exceed:

• — 40 kVA for single-phase variable auto-transformers and power supply units incorporating single-phase variable auto-transformers;
• — 200 kVA for poly-phase variable auto-transformers and power supply units incorporating poly-phase variable auto-transformers;
• — 1 kVA for single-phase variable separating transformers and power supply units incorporating single-phase variable separating transformers;
• — 5 kVA for poly-phase variable separating transformers and power supply units incorporating poly-phase variable separating transformers;
• — 25 kVA for single-phase variable isolating transformers and power supply units incorporating single-phase variable isolating transformers;
• — 40 kVA for poly-phase variable isolating transformers and power supply units incorporating poly-phase variable isolating transformers;
• — 10 kVA for single-phase variable safety isolating transformers and power supply units incorporating single-phase variable safety isolating transformers;
• — 16 kVA for poly-phase variable safety isolating transformers and power supply units incorporating poly-phase variable safety isolating transformers.

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

NOTE 2 Transformers intended to supply distribution networks are not included in the scope.

For variable auto-transformers and pow er supply units incorporating variable auto-transformers:

• — the no-load output voltage or the rated output voltage does not exceed 1 000 V a.c. or 1 415 V ripple free d.c.;
• — for independent auto-transformers the rated output voltage does exceed 50 V a.c or 120 V ripple-free d.c. but not exceed 250 V a.c. .

  NOTE 3 Normally, the variable auto-transformers and power supply units are intended to be associated with the equipment to provide voltages different from the supply voltage for the functional reasons. The protection against electric shock can be provided by other features of the equipment, such as the body.

Variable auto-transformers and power supply units incorporating variable auto-transformers intended to be used by technically skilled or trained personnel are considered as associated transformers and associated power supply units and may have a rated output voltage less than 50 V a.c. For variable separating transformers and power supply units incorporating variable separating transformers:

• — the no-load output voltage or the rated output voltage does not exceed 1 000 V a.c. or 1 415 V ripple free d.c.;
• — for portable separating transormers the rated output voltage does exceed 50 V a.c or 120 V ripple-free d.c.;
• — covered by this part may only be used where double or reinforced insulation between circuits is not required by the installation rules or by the end product standard.

NOTE 4 Normally, variable separating transformers and power supply units are intended to be associated with equipment to provide voltages different from the supply voltage for the functional reasons. 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 protective earth.

NOTE 5 Variable separating transformers and power supply units incorporating variable separating transformers intended to be used by technically skilled or trained personal are considered as associated transformers and associated power supply units and can have a rated output voltage less than 50 V a.c. or 120 V ripple-free d.c.

For variable isolating transformers and power supply units incorporating variable isolating transformers:

• — the no-load output voltage or the rated output voltage does not exceed 500 V a.c. or 708 V ripple free d.c. The no-load output voltage and the rated output voltage may be up to 1 000 V a.c. or 1 415 V ripple free d.c. for special applications or in accordance with national wiring rules;
• — for independent isolating transformers the rated output voltage does not exceed 250 V a.c.; .
• — are used where double or reinforced insulation between circuits is required by the installation rules or by the end product standard.

For variable safety isolating transformers and power supply units incorporating safety isolating transformers:

• — the no-load output voltage or the rated output voltage does not exceed 50 V a.c. or 120 V ripple-free d.c.;
• — are used where double or reinforced insulation between circuits is required by the installation rules or by the end product standard.

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

NOTE 6 Attention is drawn to the following:

• — for transformers intended to be used in vehicles, on board ships, and aircraft, additional requirements (from other applicable standards, national rules, etc.) can 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 are also considered;
• — the different conditions for transportation, storage, and operation of the transformers are also be considered;
• — additional requirements in accordance with other appropriate standards and national rules can be applicable to transformers intended for use in special environments, such as tropical environment.

Future technological development of transformers can necessitate a need to increase the upper limit of the frequencies, until then this part may be used as a guidance document.