Power Transformers

IEC 60076-14:2013 applies to liquid-immersed power transformers employing either high-temperature insulation or combinations of high-temperature and conventional insulation, operating at temperatures above conventional limits. It is applicable to:
- power transformers in accordance with IEC 60076-1;
- convertor transformers according to IEC 61378 series;
- transformers for wind turbine applications in accordance with IEC 60076-16;
- arc furnace transformers;
- reactors in accordance with IEC 60076-6. This part of IEC 60076 may be applicable as a reference for the use of high-temperature insulation materials in other types of transformers and reactors. This first edition of IEC 60076-14 cancels and replaces the second edition of the Technical Specification IEC/TS 60076-14 published in 2009. It constitutes a technical revision.

Applies to high-voltage/low-voltage self-protected liquid-filled and naturally cooled transformers for rated power 50 kVA to 1 000 kVA for indoor or outdoor use having a primary winding (high-voltage) with highest voltage for equipment up to 24 kV; a secondary winding (low-voltage) with highest voltage for equipment of 1,1 kV.

IEC 60076-12:2008 is applicable to dry-type transformers according to the scope of IEC 60076-11. It provides the means to estimate ageing rate and consumption of lifetime of the transformer insulation as a function of the operating temperature, time and the loading of the transformer.

IEC 60076-11:2018 RLV contains both the official IEC International Standard and its Redline version. The Redline version is available in English only and provides you with a quick and easy way to compare all the changes between the official IEC Standard and its previous edition.

IEC 60076-11:2018 applies to dry-type power transformers (including auto-transformers) having values of highest voltage for equipment up to and including 72,5 kV and at least one winding operating at greater than 1,1 kV. This document does not apply to:
- gas-filled dry-type transformers where the gas is not air;
- single-phase transformers rated at less than 5 kVA;
- polyphase transformers rated at less than 15 kVA;
- instrument transformers;
- starting transformers;
- testing transformers;
- traction transformers mounted on rolling stock;
- flameproof and mining transformers;
- welding transformers;
- voltage regulating transformers;
- small power transformers in which safety is a special consideration.
Where IEC standards do not exist for the transformers mentioned above or for other special transformers, this document may be applicable as a whole or in parts. This second edition cancels and replaces the first edition published in 2004 and constitutes a technical revision. The main changes with regard to the previous edition are as follows:
- Extension of the scope up to 72,5kV
- Enclosure management in regards of the performance
- Management of the dielectric and thermal features with altitude
- New climatic classes for a better adaptation of customers’ need
- Establishment of the relation between location and environmental classes
- For fire behaviour classes, limitation at 1000kVA and process of test more robust
- Introduction of Seismic class
- Recommendations for amorphous transformers
Keywords: dry-type transformers
The contents of the corrigendum of March 2019 and the Interpretation sheet 1 of July 2020 have been included in this copy.

IEC 60076-10-1:2016+A1:2020 provides supporting information to help both manufacturers and purchasers to apply the measurement techniques described in IEC 60076-10. Besides the introduction of some basic acoustics, the sources and characteristics of transformer and reactor sound are described. Practical guidance on making measurements is given, and factors influencing the accuracy of the methods are discussed. This application guide also indicates why values measured in the factory may differ from those measured in service. This application guide is applicable to transformers and reactors together with their associated cooling auxiliaries. This edition includes the following significant technical changes with respect to the previous edition:
a) extended information on sound fields provided;
b) effect of current harmonics in windings enfolded;
c) updated information on measuring methods sound pressure and sound intensity given;
d) supporting information on measuring procedures walk-around and point-by-point given;
e) clarification of A-weighting provided;
f) new information on frequency bands given;
g) background information on measurement distance provided;
h) new annex on sound-built up due to harmonic currents in windings introduced.
This consolidated version consists of the second edition (2016) and its amendment 1 (2020). Therefore, no need to order amendment in addition to this publication.

IEC 60076-10:2016 defines sound pressure and sound intensity measurement methods from which sound power levels of transformers, reactors and their associated cooling devices are determined. The methods are applicable to transformers, reactors and their cooling devices - either fitted to or separate from the transformer - as covered by the IEC 60076 and IEC 61378 series. This standard is primarily intended to apply to measurements made at the factory. Conditions on-site can be very different because of the proximity of objects, including other transformers. Nevertheless, this standard is applied to the extent possible for on site measurements. This edition includes the following significant technical changes with respect to the previous edition:
- additional useful definitions introduced;
- definition of distribution type transformers introduced for the purpose this standard;
- new clause for sound level measurement specification introduced;
- requirement for 1/3 octave band measurements introduced for transformers other than distribution type transformers;
- standard measurement distance changed from 0,3 m to 1 m for transformers other than distribution type transformers;
- height of measurement surface is now clearly defined to count from the reflecting plane;
- measurement surface formula unified;
- correction criteria for intensity method introduced;
- rules for sound measurements on dry-type reactors introduced;
- figures revised;
- new informative test report templates introduced (Annex B);
- IEC 60076-10-1 (application guide) revised in parallel providing worthwhile information for the use of this standard.

IEC 60076-1:2011 applies to three-phase and single-phase power transformers (including auto-transformers) with the exception of certain categories of small and special transformers. For those categories of power transformers and reactors which have their own IEC standards, this part is applicable only to the extent in which it is specifically called up by cross-reference in the other standard. This new edition includes the following significant technical additions with respect to the previous one:
- definition of harmonic content;
- subclause on transport;
- functional method of specification;
- connection symbols for single phase transformers;
- safety and environmental requirements;
- requirements for liquid preservation systems;
- clause on DC currents;
- vacuum, pressure and leak tests on tanks;
- facilities for condition monitoring and environmental and safety considerations.

IEC/TS 60076-19:2013, which is a Technical Specification, illustrates the procedures that should be applied to evaluate the uncertainty affecting the measurements of no-load and load losses during the routine tests on power transformers. Even if the attention is especially paid to the transformers, when applicable the specification can be also used for the measurements of reactor losses, except large reactors with very low power factor.