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TB 240 2004 SC B4/A2 JTF B4.04/A2.01 Analysis of HVDC thyristor converter transformer performance

A presentation of performance summaries with failure areas described and classified as bushings, valve windings, AC windings, static shields, load tap changers, core and magnetic shields or internal connections and leads together with short descriptions of the failures. Present transformer test methods are also evaluated for adequacy. Comparisons with the previous report are included.

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TABLE OF CONTENTS

ABSTRACT

INTRODUCTION

FAILURES REPORTED

FAILURE DESCRIPTIONS

      A) BUSHINGS, 8 + 3P FAILURES (MERCURY-ARC EXCLUDED FROM COUNT).

      B) VALVE WINDINGS, 28 + 6P FAILURES

      C) AC WINDINGS, 3 + 0P FAILURES (MERCURY-ARC EXCLUDED FROM COUNT)

      D) STATIC SHIELD, 1 + 1P FAILURES

      E) ON-LOAD TAP CHANGER (LTC), 12 + 2P FAILURES

      F) CORE AND MAGNETIC SHIELDS, 9P FAILURES (MERCURY-ARC EXCLUDED FROM  COUNT).

      G) INTERNAL CONNECTIONS, 1 + 4P FAILURES

SINGLE PHASE – THREE PHASE COMPARISON

FAILURE TRENDS

ON-LINE TRANSFORMER MONITORING

      A) EARLY WARNING

      B) MULTIGAS ANALYSIS

      C) BUSHING MONITORING

      D) ON-LINE PARTIAL DISCHARGE MEASUREMENTS

      E) EXPERIENCE WITH MONITORING AT NELSON RIVER SYSTEM

      F. VYBORG TRANSFORMER MONITORING [13]

PREVIOUS TEST RECOMMENDATIONS

NEW ISSUES ABOUT CONVERTER TRANSFORMER TESTS

DESIGN REVIEW

CONCLUSIONS

ACKNOWLEDGEMENTS

REFERENCES

APPENDIX

       I. ELECTRA NO. 155 AUGUST 1994, "IN-SERVICE PERFORMANCE OF HVDC CONVERTER TRANSFORMERS…..”, 1972 – 1990

            TABLE 1. SUMMARY – CAUSE OF FAILURES

            TABLE 2. SUMMARY – FAILURE RATE

            RECOMMENDATIONS FOR DESIGN REVIEW

      II.JTF B4.04/A2-1 TRANSFORMER FAILURE RATE

            ALL REPORTING SYSTEMS, 1991-2002

      III COMBINED TRANSFORMER FAILURE RATE

            ALL REPORTING SYSTEMS, YEAR COMMISSIONED THROUGH 2002