CEI EN 61558-2-23

BILINGUAL

Replacement:

This part of IEC 61558 deals with the safety of
transformers for construction
sites and power supply units
incorporating transformers for construction sites.
Transformers incorporating electronic
circuits are also covered by this standard.

NOTE 1 Safety includes electrical, thermal and mechanical
aspects.

Unless otherwise specified, from here onward, the term
transformer covers transformers for construction
sites and power supply units incorporating
transformers for construction sites.

This part is applicable to stationary or
portable, single-phase or polyphase, air-cooled
(natural or forced) independent or
associated transformers, being
isolating or safety isolating dry-type
transformers for the use on construction
sites. The windings may be encapsulated or
non-encapsulated.

The rated supply voltage does not exceed 1 000
V a.c., and the rated supply frequency and the
internal operating frequencies do not exceed 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 operating
frequencies higher than 500 Hz. Where the two requirements
are in conflict the most severe take precedence.

The rated output does not exceed:

– 25 kVA for single-phase transformers;

– 40 kVA for poly-phase 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.

Isolating transformers and power
supply units incorporating isolating transformers
for construction sites have a no-load output
voltage and a rated output voltage
exceeding 50 V a.c. and not exceeding 250 V a.c.

Safety isolating transformers and power supply
units incorporating safety isolating transformers for construction
sites have a no-load output voltage and a rated output voltage not
exceeding 50 V a.c.

NOTE 3 This standard is applicable to transformers for the
supply of electricity in locations as specified in IEC 60364-7-704.
The latter also specifies the protection by using an earthed
midpoint or starpoint of the output winding.

Transformers and power supply
units covered by this part are used in applications where
it is required by the installation rules or by the appliance
specification for protection purposes.

When the transformers or power supply
units are incorporated into low voltage switchgear
and controlgear assemblies for construction sites as
specified in IEC 60439-4, the additional requirements of IEC
60439-4 will apply to the assembly.

NOTE 4 For transformers filled with liquid
dielectric or pulverised material, such as sand, additional
requirements are under consideration.

NOTE 5 Attention is drawn to the following:

– measures to protect the enclosure and the
components inside the enclosure against external
influences like fungus, vermin, termites, solar-radiation and icing
should also be considered;

– the different conditions for transportation, storage, and
operation of the transformers and power
supply units should also be considered;

– additional requirements in accordance with other appropriate
standards and national rules may be applicable to
transformers and power supply
units intended for use in special environments such as
tropical environment.

NOTE 6 Future technological development of
transformers may necessitate a need to increase
the upper limit of the frequencies, until then this standard may be
used as a guidance document.