IEC 61558-2-12:2001 Safety of power transformers, power supply units and similar devices - Part 2-12: Particular requirements for constant voltage transformers
Replacement:
This International Standard deals with all aspects of safety such as electrical, thermal and mechanical.
This part of IEC 61558 applies to stationary or portable, single-phase or polyphase, air-cooled (natural or forced), associated or independent:
- constant voltage auto-transformers
- constant voltage separating transformers
- constant voltage isolating transformers
- constant voltage safety isolating transformers
having a rated supply voltage not exceeding 1 000 V a.c., a rated frequency not exceeding 500 Hz, an internal operational frequency not exceeding 30 kHz and no limitation of the rated output.
NOTE 1 The technological development of transformers might imply a need to increase the higher limit of the internal operational frequency; until such time, this standard may be used as a guide.
Constant voltage independent auto-transformers
- have a no-load output voltage and a rated output voltage exceeding 50 V a.c. or 120 V ripple-free d.c. and not exceeding 1 000 V a.c. or 1 415 V ripple-free d.c.;
- are used where no insulation between circuits is required by the installation rules or by the equipment specification.
Constant voltage associated auto-transformers
- have a no-load output voltage and a rated output voltage not exceeding 1 000 V a.c. or 1 415 V ripple-free d.c.
Constant voltage independent separating transformers
- have a no-load output voltage and a rated output voltage exceeding 50 V a.c. or 120 V ripple-free d.c. and not exceeding 1 000 V a.c. or 1 415 V ripple-free d.c.;
- are used where double or reinforced insulation between circuits is not required by the installation rules or by the appliance specification.
Constant voltage associated separating transformers
- have a no-load output voltage and a rated output voltage not exceeding 1 000 V a.c. or
1 415 V ripple-free d.c.
Constant voltage isolating transformers
- have a no-load output voltage and/or a rated output voltage exceeding 50 V a.c. or 120 V ripple-free d.c. and not exceeding 500 V a.c. or 708 V ripple-free d.c.; the no-load output voltage and the rated output voltage may exceed these limits in order to be in accordance with the national wiring rules or special purposes; however, they shall not exceed 1 000 V a.c. or 1 415 V ripple-free d.c.;
- are used where double or reinforced insulation between circuits is required by the installation rules or by the appliance specification.
Constant voltage safety isolating transformers
- have a no-load output voltage and a rated output voltage not exceeding 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 appliance specification.
This standard is applicable to dry-type constant voltage transformers. The windings may be encapsulated or non-encapsulated.
NOTE 2 For constant voltage transformers filled with liquid dielectric or pulverized material, such as sand, additional requirements are under consideration.
NOTE 3 Attention is drawn to the fact that
- for transformers intended to be used in tropical countries, special requirements may be necessary;
- in locations where special environmental conditions prevail, particular requirements may be necessary.
NOTE 4 For higher no-load output voltages or circuit voltages, additional requirements are necessary but this standard may be used as a guide.
IEC 61558-2-12:2001 history
0000 IEC 61558-2-12:2024 RLV
2011IEC 61558-2-12:2011 Safety of transformers, reactors, power supply units and combinations therof - Part 2-12: Particular requirements and tests for constant voltage transformers and power supply units for constant voltage
2001IEC 61558-2-12:2001 Safety of power transformers, power supply units and similar devices - Part 2-12: Particular requirements for constant voltage transformers