NATIONAL FOREWORD
Doc: ET 16(6636)
IS 2026(Part 1)
IEC 60076-1:2011
BUREAU OF INDIAN STANDARDS
DRAFT FOR COMMENTS ONLY
(Not to be reproduced without the permission of BIS or used as a STANDARD )
Draft Indian Standard
POWER TRANSFORMERS ─ PART 1: GENERAL
(Second Revision)
Last date for receipt of comments is: 25-07-2013
________________________________________________________________________________
Power Transformers Sectional Committee, ET 16
This draft Indian Standard (second revision) which is identical with IEC 60076-1:2011
‘Power transformers: Part 1 General’ issued by the International Electrotechnical
Commission (IEC) is proposed to be adopted by the Bureau of Indian Standards on the recommendation of the Transformers Sectional Committee and approval of the
Electrotechnical Division Council.
This standard was first published in 1962 and covered naturally cooled oil-immersed transformers. With subsequent amendments forced cooled transformers were included, use of synthetic liquids as cooling medium was permitted and requirements for aluminium winding were incorporated.
First revision was undertaken with a view to bringing it in line with the revision of IEC
76:1967 ‘Power transformers’. The second revision has been based on IEC 60076-1:2000
‘Power 1: General’ issued by the International Electrotechnical Commission with following modifications. In this revision the temperature of ambient air and cooling medium oil is as per Indian Environment and tests are conducted accordingly. In this revision it is completely aligned with latest IEC standard.
The text of the IEC standard has been approved as suitable for publication as Indian
Standard without deviations. Certain conventions are, however, not identical to those used in Indian standards. Attention is particularly drawn to the following: a) Wherever the words ‘International Standard’ appear referring to this standard, they should be read as ‘Indian Standard’ b) Comma (,) has been used as a decimal marker, while in Indian Standards the current practice is to use a point (.) as the decimal marker.
In this adopted standard, references appear to certain International Standards for which
Indian Standard also exist. The corresponding Indian St andard, which are to be substituted

in their respective places are listed below along with their degree of equivalence for the editions indicated:
BISDG NOTE – A separate standard on Distribution Transformer (IS 1180) is available for rating upto 2500 kVa (Under revision). These ratings are also covered in
IS 2026-1. Therefore suitable para may be added to exclude DT from the scope of the standard. Moreover, ratings, ambient temperature etc. need to be looked into from
Indian perspective members are requested to comment on this.
International Standard
IEC 60076-2, Power transformers – Part
2: Temperature rise for liquid-immersed transformers
IEC 60076-3:2000, Power transformers –
Corresponding Indian Standard
IS 2026(Part 2):2010 Power
Transformers - Part 2 Temperature rise (first revision)
IS 2026(Part 3):2009 Power
Degree
Equivalence
Technically
Equivalent
Identical of
Part 3: Insulation levels, dielectric tests and external clearances in air
IEC 60076-5:2006, Power transformers –
Part 5: Ability to withstand short circuit
IEC 60076-10:2001, Power transformers
– Part 10: Determination of sound levels
IEC 60076-11:2004, Power transformers
– Part 11: Dry-type transformers
IEC 60137:2008, Insulated bushings for alternating voltages above 1 000 V
Transformers - Part 3 Insulation levels, dielectric tests and external clearances in air (third revision)
IS 2026(Part 5):2011 Power
Transformers - Part 5 Ability to withstand short circuit (first revision)
IS 2026(Part 10):2009 Power
Transformers - Part 10 Determination of sound levels
IS 11171:1098 Dry-Type Power
Transformers
IS 2099 : 1986 Bushings for
Technically
Equivalent
Identical
Technically
Equivalent
Identical alternating voltages above 1000 volts
(Second Revision)
IS 8468:1977 On-load Tap Changers Not Equivalent IEC 60214-1:2003, Tap-changers – Part
1: Performance requirements and test methods
IEC 60296:2003, Fluids for electrotechnical applications – Unused mineral insulating oils for transformers
IS 335:1993 New Insulating Oils Do and switchgear
ISO 9001:2008, Quality management systems – Requirements
IS/ISO 9001:2001 Quality
Management Systems - Requirements
Identical
The Technical Committee responsible for the preparation of this standard has reviewed the provisions of the following International Standards referred to in this adopted standard and has decided that they are acceptable for use in conjunction with this standard .
International Standard
IEC 60721-3-4:1995
Title
Classification of environmental conditions – Part 3: Classification of

groups of environmental parameters and their severities – Section 4:
Stationary use at nonweather protected locations
Only English language text has been retained while adopting it in this Indian Standard and as such the page numbers given here are not the same as in the International Standard
For the purpose of deciding whether a particular requirement of this standard is complied with the final value, observed or calculated, expressing the result of a test or analysis shall be rounded off in accordance with IS 2:1960 ‘Rules for rounding off numerical values
( revised )’. The number of significant places retained in the rounded off value should be the same as that of the specified value in this standard.
Note: The technical content of the documents is not available on website. For details, please refer the corresponding IEC 60076-1:2011 or kindly contact:
Head
Electrotechnical Department
Bureau of Indian Standards
9, B. S. Zafar Marg,
New Delhi-110002
Email: e etd@bis.org.in
Telephone/ fax: 011-23231192
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