The Transformer Committee (A2)

1. CIGRÉ Study Committee ReportSCA2October 19, 2008WinnipegClaude Rajotte, Hydro-Québec-TransÉnergie

2. The Transformer Committee (A2) Scope : Design, construction, manufacture and operation for all kinds of power transformers, including industrial , DC converters and phase-shift transformers and for all types of reactors and transformer components (bushing, tap-changer…) In the past ( known as SC12 ) activities were focussed on design problems related to the rapid increase of rated voltage and power Today, the two Strategic Directions for A2 future activities are : • Services to Customers ( Reliability, Life management, Economics, Tutorials, ...) • Technology Issues (Safety, New technologies and New concepts, Electrical environment, Pre-standardisation work, ...)  Chairman: Pierre Boss (CH)Secretary: Claude Rajotte (CA)

3. WG completed recently WG A2.26 Mechanical condition assessment analysis of transformer windings using FRA Patrick Picher (CA) - Guidance for FRA,, - Compare different practices and propose and optimised practice- FRA interpretation, modelling, complementary methods WG A2.27 Recommendations for monitoring facilities -Paul Jarman (UK ) - Review existing and developing condition monitoring systems and practice - Propose standardization - Make recommendations for the provision of sensors facilities or data from new transformers TF A2.30 Moisture in transformer - V. Sokolov (UA) - Moisture equilibrium and moisture migration within transformer insulation systems - Critical Temperature on Bubble Evolution of oil-immersed Transformer under overload condition - Considered new research works done in this field like - bound water- effect of acids on water in oil

4. Present A2 WG WG A2.24 Thermal performances Ian Declercq (BE ) - Fundamentals on thermal ageing - Ratings of new transformers - standardization - Practical applications for in service transformers - overload capability, reliability and economics WG A2.32 Copper sulphide in power transformer insulation Mats Dahlund (SE) - Created in response to several recent transformer failures due to cooper sulphide - Oil testing and specification issues – CEI standard - Methods to identify units in danger - Recommendations for counter-measures to stop or retard the process - Improve understanding of the problem WG A2-33 -Fire Safety (A. Petersen/AU) - Avoidance of tank rupture - Precaution to fire victim - Precautions to fire origin

5. Present A2 WG WG & TF underway (suite) : WG A2-34 Guide for Transformer Maintenance (C. Rajotte/CA) • define a best practices list of periodic actions applied in service or with outage • address advanced maintenance activities, such as oil additives, oil filtering, oil regeneration, and insulation drying • human and material aspects of transformer maintenance, maintenance planning, maintenance tasks tracking, maintenance resources, cost references, level of competences required for different tasks, training, on-site repair, etc. WG A2-35 Experiences in service with new liquids (R. Martin/UK) - Physical, Chemical and Electrical properties of alternative fluids in comparison with Mineral oil - How the use of the alternative fluids impinges on equipment design • Gather and review in service uses of the new fluids ; Where and how used ;Power and distribution transformers; Review in-service; concerns/needs, • Review relevance of in service tests (Lab and field) to the new fluids as opposed to mineral oil • Maintenance and retrofilling • Reliability, longevity and the interaction of fluids with solid insulation. There is no Canadian member in this WG.

6. Present A2 WG WG A2-36 Guide for Transformer Procurement Process (T. Breckenbridge / UK). -Review and update of the existing CIGRE A2 documents on procurement -Taking into account the current market conditions and the new commercial pressures that customers operate under - Prepare a new guide for assessing the capability of transformer manufacturers that evaluates technical competence and experience WG A2-37 Transformer Reliability Survey (S. Tenbohlen/DE). • Review all existing national surveys and study different practices (data collection, compilation, etc.) • Discuss the differences and identify best practices • Compile and present the information available in these national survey reports • Make recommendations to improve the situation. There is no Canadian member in this WG.

7. Present A2 WG WG A2-38 Transformer Thermal Modelling (J. Lapworth/UK). • Describe the state of the art techniques in transformer thermal modelling to evaluate winding hottest spot as well as hot spots on other metallic parts • Examples of advanced transformer modelling tools • Examples of application of hottest spot direct measurement and best practices • Advantages and limitations of these technologies • Recommendation for standard improvement. • Applicability of thermal modelling to revise old transformer thermal performance

8. Present A2 JWG WG A2/B4.28 HVDC Converter Transformer Milan Saravolac (FR) • WG started on recommendation of WG B4.04/A2 “Analysis of HVDC Thyristor Converter Transformers Performance” • Review Reliability Questionnaire • Technical Specification for HVDC converter transformers • Design Review Guide for HVDC converter transformers • Test specifications JWG A2/C4.39 - Electrical Transient Interaction between Transformers and the Power System (A.da Costa Oliveira Rocha/BR): • Assess and discuss the different types of electrical transient interaction between transformers and other components of the T&D power system • Discuss the general increase in transformer dielectric failures in the system.

9. Other activities with liaisons WG D1-01: Impregnated insulation (L. Lundgaard / NO) TF D1-01-12: Oil maintenance -Insulating oil reclamation and and dechlorination (B. Pahlavanpour / UK TF D1-01-13: Furans for diagnostics (Marie-Claude Lessard / CA TF D1-01-14: Dielectric response diagnoses for transformer windings (S. Gubanski / SE). TF D1-01-15: Progress in DGA techniques and diagnoses (M.Duval / CA) TF D1-01-17: Oxidation Stability of Transformer Insulating Oils (I. Atanasova Höhlein / DE) WG C1-10: CIGRE Glossary (A. Popescu /RO & W. Reinke / US) WG A3-22: Technical requirements for substation equipment exceeding 800kV (Dr. Hiroki Ito / JP)

10. Recent CIGRE BROCHURES Scope Ref Year Thermal aspects 96 1995 Static electrification 170 2000 Effect of particles 157 2000 Customer specifications 156 2000 Design reviews 204 2002 Short circuit performance 209 2002 Life management of transformers 227 2003 Economics of Transformer Management 248 2004 Guide: Transformer Data Lifetime Management 298 2006 Mechanical Cond. Assessment of Xfo Windings 342 2008 Recom. for Condition Monitoring & Assessment 343 2008 Moisture Equilibrium within Transfo. Insulation 349 2008

11. A2 Tutorial & External Events •Support to the Conf. on Transient Phenomena in Large Electric Power Systems in Zagreb/Croatia (April 2007) • International Conference on Power Transformers, May 30-31, 2007 -Torun, Poland • Workshop on Variable Frequency Diagnostics Dielectric response and FRA, Stockholm, Sweden, Sept. 2007 • Conf. on Tfo Technology in Serbia and Rumania, Sept 2007 • Joint Colloquium SC A2/D1 in Bruges, Belgium, October 2007 • International Advanced Research Workshop on Transformers, Vigo, Spain, October 2007 • Matpost 07, Lyon/France, November 2007 • CMD2008 – Int. Conf. on Condition Monitoring and Diagnostics, Beijing, China, April 2008

12. Past SC A2 Sessions & Colloquium 2004 Paris - Thermal Performances & On-site operations 2005 Moscow - Colloquium on Transformers Reliability (Technical, Economical and Strategic Aspects) - New Developmentof electrical transients on transformer performances 2006 Paris - Transformers Reliability, Technical, Economical and Strategic Aspects - New Development of electrical transients on  transformer performances - Phase-Shifter Transformers 2007 Bruges -Guidance in new insulation liquids for improvement on performance and reliability -Life estimation of transformers in service -Reactors and related items 2008 Paris -Performance in service of new insulation systems for transfo. -Reliability and risk assessment of transformers in service -Reactors (shunt, shunt with regulation, series, neutral)and related items

13. Future SC A2 Sessions & Colloquium The next SCA2 Colloquium will be held in South Africa in coordination with SC A3 (High Voltage Equipment and B3 (Substations) during the period August 17th-21st, 2009. The preferential subjects are: - Substation layouts - End of Life Asset Management - Maintenance of Equipment for Maximum Reliability For Paris 2010, the preferential are: - Catastrophic failure - Transformer Life - Transformer Modelling