CIGRÉ Study Committee Report

SCA2

October 19, 2008 Winnipeg

Claude Rajotte, Hydro-Québec-TransÉnergie 1

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) 2

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 3

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 4

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.

5

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.

6

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 7

Present A2 JWG

WG A2/B4.28 HVDC Converter Transformer Milan Saravolac (FR) • WG started on recommendation of WG B4.04/A2 • Review Reliability Questionnaire • Test specifications “Analysis of HVDC Thyristor Converter Transformers Performance” • Technical Specification for HVDC converter transformers • Design Review Guide for HVDC converter transformers 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.

8

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) 9

Recent CIGRE BROCHURES

Scope Ref

Thermal aspects Static electrification Effect of particles Customer specifications 96 170 157 156 Design reviews Short circuit performance Life management of transformers Economics of Transformer Management 204 209 227 248 Guide: Transformer Data Lifetime Management 298 Mechanical Cond. Assessment of Xfo Windings 342 Recom. for Condition Monitoring & Assessment 343 Moisture Equilibrium within Transfo. Insulation 349

Year

1995 2000 2000 2000 2002 2002 2003 2004 2006 2008 2008 2008 10

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 11

Past SC A2 Sessions & Colloquium

2004 Paris - Thermal Performances & On-site operations 2005 Moscow - Colloquium on Transformers Reliability (Technical, Economical and Strategic Aspects) - New Development of 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

12

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 13