IEC 61558-2-23:2010 Safety of transformers, reactors, power supply units and combinations thereof - Part 2-23: Particular requirements and tests for transformers and power supply units for construction sites
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 drytype
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.
IEC 61558-2-23:2010 history
2010IEC 61558-2-23:2010 Safety of transformers, reactors, power supply units and combinations thereof - Part 2-23: Particular requirements and tests for transformers and power supply units for construction sites
2000IEC 61558-2-23:2000 Safety of power transformers, power supply units and similar devices - Part 2-23: Particular requirements for transformers for construction sites