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.
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 power supply units incorporating variable autotransformers;
– variable separating transformers and power supply units incorporating variable
separating 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.
– 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;
For variable auto-transformers and power supply units incorporating variable autotransformers:
– 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. .