IEC 62975:2021 provides procedures and guidelines that are intended for the use and maintenance of natural ester liquid in sealed transformers and other electrical equipment. This document is applicable to natural esters, originally supplied conforming to IEC 62770 and other applicable standards (e.g. ASTM D6871) in transformers, switchgear and electrical apparatus where liquid sampling is practical and where the normal operating conditions specified in the equipment specifications apply. At present, there is a limited amount of information available for electrical equipment other than transformers. This document is also intended to assist the power equipment operator to evaluate the condition of the natural ester and maintain it in a serviceable condition. It also provides a common basis for the preparation of more specific and complete local codes of practice. The document includes recommendations on tests and evaluation procedures and outlines methods for reconditioning and reclaiming the liquid, when necessary.<\/p>\n
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| 2<\/td>\n | undefined <\/td>\n<\/tr>\n | ||||||
| 4<\/td>\n | English CONTENTS <\/td>\n<\/tr>\n | ||||||
| 6<\/td>\n | FOREWORD <\/td>\n<\/tr>\n | ||||||
| 8<\/td>\n | INTRODUCTION <\/td>\n<\/tr>\n | ||||||
| 9<\/td>\n | 1 Scope 2 Normative references <\/td>\n<\/tr>\n | ||||||
| 11<\/td>\n | 3 Terms and definitions 4 Categories of equipment <\/td>\n<\/tr>\n | ||||||
| 12<\/td>\n | 5 In-service natural ester diagnostic tests Tables Table 1 \u2013 Categories of equipment <\/td>\n<\/tr>\n | ||||||
| 13<\/td>\n | 6 Evaluation of natural esters in new equipment Table 2 \u2013 Diagnostic tests for in-service natural esters <\/td>\n<\/tr>\n | ||||||
| 14<\/td>\n | 7 Evaluation of natural ester in equipment in service 7.1 General Table 3 \u2013 Recommended limits for natural esters properties after filling in new electrical transformers and reactors prior to energization <\/td>\n<\/tr>\n | ||||||
| 15<\/td>\n | 7.2 Frequency of examination <\/td>\n<\/tr>\n | ||||||
| 16<\/td>\n | 7.3 Testing procedures 7.3.1 Field tests 7.3.2 Laboratory tests 7.4 Classification of in-service natural esters Table 4 \u2013 Recommended frequency of testing a <\/td>\n<\/tr>\n | ||||||
| 17<\/td>\n | Table 5 \u2013 Recommended limits for in service natural esters in transformers <\/td>\n<\/tr>\n | ||||||
| 21<\/td>\n | 8 General requirements for corrective actions 9 Interpretation of results 9.1 General 9.2 Colour and appearance 9.3 Breakdown voltage <\/td>\n<\/tr>\n | ||||||
| 22<\/td>\n | 9.4 Viscosity 9.5 Acidity 9.6 Dielectric dissipation factor (DDF) and resistivity <\/td>\n<\/tr>\n | ||||||
| 23<\/td>\n | 9.7 Dissolved gas-in-oil 9.8 Flash and fire points 9.9 Interfacial tension (IFT) <\/td>\n<\/tr>\n | ||||||
| 24<\/td>\n | 9.10 Density 9.11 Pour point 9.12 Additives 9.13 Particle count 9.14 Compatibility and miscibility of natural esters <\/td>\n<\/tr>\n | ||||||
| 25<\/td>\n | 9.15 Oxidation stability 9.16 Polymerization <\/td>\n<\/tr>\n | ||||||
| 26<\/td>\n | 10 Sampling of natural esters from equipment <\/td>\n<\/tr>\n | ||||||
| 27<\/td>\n | Annex A (informative)Water and natural ester liquids A.1 General A.2 Water content A.2.1 General A.2.2 Water in natural esters <\/td>\n<\/tr>\n | ||||||
| 28<\/td>\n | Table A.1 \u2013 Typical values for A and B for different insulating liquids [10] <\/td>\n<\/tr>\n | ||||||
| 29<\/td>\n | A.3 Moisture equilibrium between liquid and solid insulation Figures Figure A.1 \u2013 Moisture saturation values between liquids versus temperature [10] Table A.2 \u2013 Guidelines for interpreting data expressed in relative saturation <\/td>\n<\/tr>\n | ||||||
| 30<\/td>\n | Figure A.2 \u2013 Example of water (high concentrations) equilibrium curves for paper and natural ester [11] <\/td>\n<\/tr>\n | ||||||
| 31<\/td>\n | Figure A.3 \u2013 Example of water (medium concentrations) equilibrium curves for paper and liquid [11] Figure A.4 \u2013 Example of water (low concentrations) equilibrium curves for paper and liquid [11] <\/td>\n<\/tr>\n | ||||||
| 32<\/td>\n | Annex B (informative)Replacement and treatments of natural esters in transformers B.1 Transformer retrofilling with natural esters <\/td>\n<\/tr>\n | ||||||
| 33<\/td>\n | B.2 Reconditioning and reclaiming B.2.1 General B.2.2 Reconditioning <\/td>\n<\/tr>\n | ||||||
| 34<\/td>\n | B.2.3 Reclaiming <\/td>\n<\/tr>\n | ||||||
| 35<\/td>\n | Annex C (informative)Use of natural ester liquids with on-load tap-changers (OLTCs) <\/td>\n<\/tr>\n | ||||||
| 37<\/td>\n | Bibliography <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" Natural esters. Guidelines for maintenance and use in electrical equipment<\/b><\/p>\n |