Power Transformers

IEC 60076-22-5:2021 covers electric pumps used in the cooling circuits of power transformers and reactors. It applies to electric pumps mounted on liquid immersed power transformers according to IEC 60076-1 and reactors according to IEC 60076-6 with and without conservator for indoor or outdoor installation.
It outlines the operation requirements for the electrical and hydraulic performance, mechanical design, routine testing and type testing. Additionally, performance and dimensions of preferred sizes of pump sets are specified in informative annexes.
The pumps covered in this document are rotodynamic pumps driven by a squirrel cage induction motor that is immersed in the insulating liquid.
Pump sets conforming to this document can be of in-line or end suction design.

IEC 60076-22-4:2019 applies to liquid to water heat exchangers, using forced water and forced liquid circuits, used on liquid immersed power transformers according to IEC 60076-1 and reactors according to IEC 60076-6 with and without conservator for indoor or outdoor installation. It outlines the service conditions and the mechanical and electrical requirements that are common to this equipment.
It also outlines the operation requirements specific to this equipment as well as the preferred dimensions relevant for interchangeability and the type and routine tests to be performed.

IEC 60076-22-3:2019 applies to liquid to air heat exchangers, using forced air and forced liquid circuits, used on liquid immersed power transformers according to IEC 60076-1 and reactors according to IEC 60076-6 with and without conservator for indoor or outdoor installation. It outlines the service conditions and the mechanical and electrical requirements that are common to this equipment. It also outlines the operation requirements specific to this equipment as well as the preferred dimensions relevant for interchangeability and the type and routine tests to be performed.

IEC 60076-22-2:2019 applies to radiators mounted on liquid immersed power transformers according to IEC 60076-1 and reactors according to IEC 60076-6 with and without conservator for indoor or outdoor installation. It outlines the service conditions and the mechanical and electrical requirements that are common to this equipment. It also outlines the operation requirements specific to this equipment as well as the preferred dimensions relevant for interchangeability and the type and routine tests to be performed.

IEC 60076-22-1:2019 applies to protective devices mounted on liquid-immersed power transformers in accordance with IEC 60076-1 and reactors in accordance with IEC 60076-6 with or without conservator for indoor or outdoor installation. It outlines the service conditions and the mechanical and electrical requirements that are common to all the devices, which are relevant for the safety of the machine having a function of signalization of abnormal operating conditions. It also outlines the operation requirements specific to each device as well as, in some cases, the preferred dimensions relevant for interchangeability and the type and routine test to be performed.

IEC 60076-21:2018 describes electrical, mechanical and test requirements of liquid-immersed, single- and three-phase, 50 Hz and 60 Hz, self and forced-air cooled, distribution, overhead and substation, step-voltage regulators, 1 000 kVA (single-phase units) or 3 000 kVA (three-phase units) and smaller, 34 500 volts and below (2 400 V minimum) and their associated controls. Requirements, references and definitions relevant to either IEC or IEEE contexts are given and their use is described in Clause 4. This publication is published as an IEC/IEEE Dual Logo standard. This second edition cancels and replaces IEC 60076-21, published in 2011, and IEEE Std C57.15-2009. This edition includes the following significant technical changes with respect to IEC 60076­21:2011/IEEE Std C57.15-2009:
a) updated list of normative and bibliography IEC and IEEE references and their associated text;
b) updated tables of preferred ratings for inclusion of maximum system voltage (Um), nominal system voltage and rated voltage (Ur);
c) inclusion of tables for optional fan-cooled ratings, external dielectric clearances and sound pressure levels;
d) revision of short-circuit requirements for distribution and substation voltage regulators;
e) inclusion of an universal interface between control enclosure and apparatus;
f) inclusion of tap-changer routine and type tests;
g) inclusion of audible sound pressure emissions test procedures;
h) inclusion of tank enclosure integrity type test procedures;
i) update of control environmental IEC reference test standard.

IEC TS 60076-20:2017(E) is applicable to transformers in the scope of IEC 60076-1. It proposes two methods of defining an energy efficiency index and introduces three methods of evaluating the energy performance of a transformer. The appropriate method is chosen by agreement between purchasers and manufacturers or according to local regulations.
The contents of the corrigendum of January 2018 have been included in this copy.

IEC 60076-2:2011 applies to liquid-immersed transformers, identifies power transformers according to their cooling methods, defines temperature rise limits and gives the methods for temperature rise tests. This new edition includes the following significant technical changes with respect to the previous edition:
- the winding hot-spot temperature rise limit was introduced among the prescriptions;
- the procedures for the temperature rise test were improved in relation to the new thermal requirements;
- five informative annexes were added in order to facilitate the implementation of this standard.

IEC 60076-18:2012 covers the measurement technique and measuring equipment to be used when a frequency response measurement is required either on-site or in the factory either when the test object is new or at a later stage. This standard is applicable to power transformers, reactors, phase shifting transformers and similar equipment.

IEC 60076-15:2015 applies to three-phase and single-phase gas-filled power transformers (including auto-transformers) with the exception of certain categories of small and special transformers such as:
- single-phase transformers with rated power less than 1 kVA and three-phase transformers less than 5 kVA;
- transformers, which have no windings with rated voltage higher than 1 000 V;
- instrument transformers;
- traction transformers mounted on rolling stock;
- starting transformers;
- testing transformers;
- welding transformers. This second edition of IEC 60076-15 cancels and replaces the first edition published in 2008 and constitutes a technical revision. The following main technical changes from the first edition are:
- Modified in accordance with the related revised standards of IEC 60076-1, IEC 60076-2, IEC 60076-3 and related items of SF6 gas in the revised standard of "High-voltage switchgear and controlgear;
- Added the clause "minimum power under alternative cooling modes";
- Added the clause "safety, environmental and other requirements";
- Added the clause "d.c. currents in neutral circuits";
- Added the clause "electromagnetic compatibility (EMC)";
- Added the clause "high frequency switching transients".