IEC TR 62874, which is a Technical Report provides guidance for the estimation of consumed thermal life of transformers’ cellulosic insulators, through the analysis of some compound dissolved in the insulating mineral oil. A comparison between analytical results of 2-furfural (2-FAL) and carbon oxides and their correspondent typical values estimated for different families of equipment gives information on the estimated thermal degradation of papers.<\/p>\n
The ageing rate of insulating papers can be evaluated, in short time ranges (e.g. 1 year), by regularly monitoring 2-FAL and carbon oxides content in the oil and by comparing them to typical rates of increase.<\/p>\n
A statistical approach for the estimation of paper thermal degradation, and the evaluation of ageing rate is given.<\/p>\n
Typical values for concentrations and rates of increase of the parameters related to paper ageing were extrapolated from a statistical database collected, and are reported in Annex A. They may be used as a rough guide, but they should not be considered as threshold values.<\/p>\n
This Technical Report is only applicable to transformers and reactors filled with insulating mineral oils and insulated with Kraft paper. The approaches and procedures specified should be taken as a practical guidance to investigate the thermal degradation of cellulosic insulation, and not as an algorithm to calculate the actual degree of polymerization (DP) of papers.<\/p>\n
The paper thermal life evaluation protocol described in this Technical Report applies to mineral oil impregnated transformers and reactors, insulated with Kraft paper. Any equipment filled with insulating liquids other than mineral oil (i.e. esters, silicones) or insulated with solid materials other than Kraft paper (i.e. TUP \u2013 thermally upgraded Kraft paper, synthetic polymers) is outside of the scope of this Technical Report.<\/p>\n
This Technical Report is applicable to equipment that has been submitted to a regular monitoring practice during the service, and for which maintenance and fault history is known.<\/p>\n
| PDF Pages<\/th>\n | PDF Title<\/th>\n<\/tr>\n | ||||||
|---|---|---|---|---|---|---|---|
| 4<\/td>\n | 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 | ||||||
| 10<\/td>\n | 3 Significance 3.1 General 3.2 Thermal and mechanical degradation of paper 3.2.1 General 3.2.2 Impact of temperature <\/td>\n<\/tr>\n | ||||||
| 11<\/td>\n | 3.2.3 Impact of humidity and oxygen Figures Figure 1 \u2013 Schematic diagram showing rate of ageing k, depending on different ageing mechanisms <\/td>\n<\/tr>\n | ||||||
| 12<\/td>\n | 3.3 Symptoms of paper ageing in insulating oil 3.3.1 General Figure 2 \u2013 Relationship between mechanical properties of insulating paper and paper degree of polymerization (DP) [5]. <\/td>\n<\/tr>\n | ||||||
| 13<\/td>\n | 3.3.2 Volatile by-products 3.3.3 Soluble by-products 3.3.4 Insoluble by-products 3.4 Operational parameters influencing paper thermal ageing <\/td>\n<\/tr>\n | ||||||
| 14<\/td>\n | 3.5 Role of oil type and condition 3.6 Fault conditions that may affect thermal ageing <\/td>\n<\/tr>\n | ||||||
| 15<\/td>\n | 3.7 Maintenance operations that may affect thermal ageing indicators 3.7.1 General 3.7.2 Effects of oil reconditioning 3.7.3 Effects of oil reclamation 3.7.4 Effects of oil change <\/td>\n<\/tr>\n | ||||||
| 16<\/td>\n | 4 Monitoring protocol 4.1 General 4.2 Parameters 4.2.1 Basic monitoring 4.2.2 Complementary monitoring 4.3 Recommended testing frequencies <\/td>\n<\/tr>\n | ||||||
| 17<\/td>\n | 5 Typical values of paper ageing symptoms 5.1 General 5.2 Families of equipment <\/td>\n<\/tr>\n | ||||||
| 18<\/td>\n | 6 Estimation of paper thermal degradation and ageing rate 6.1 General approach 6.2 Practice <\/td>\n<\/tr>\n | ||||||
| 19<\/td>\n | 7 Actions Figure 3 \u2013 Example of flow-chart for the estimation of paper degradation conditions <\/td>\n<\/tr>\n | ||||||
| 21<\/td>\n | Annex A (informative) Typical values tables A.1 General warning A.2 2-FAL typical values A.2.1 General A.2.2 Family: GSU (generation step-up units) Tables Table A.1 \u2013 2-FAL typical values for GSU transformers, filled with uninhibited mineral oil (based on a population of 1\u00a0860 units) Table A.2 \u2013 2-FAL typical values for GSU transformers, filled with inhibited mineral oil (based on a population of 176 units) <\/td>\n<\/tr>\n | ||||||
| 22<\/td>\n | A.2.3 Family: network transmission units A.2.4 Family: large distribution units A.2.5 Family: industrial distribution units Table A.3 \u2013 2-FAL typical values for network transmission transformers, filled with uninhibited mineral oil (based on a population of 2\u00a0845 units) Table A.4 \u2013 2-FAL typical values for large distribution transformers, with open breathing conservator, filled with uninhibited mineral oil (based on a population of 7\u00a0107 units) Table A.5 \u2013 2-FAL typical values for large distribution transformers, with sealed conservator, filled with uninhibited mineral oil (based on a population of 288 units) Table A.6 \u2013 2-FAL typical values for industrial distribution transformers, filled with uninhibited mineral oil (based on a population of 3\u00a0885 units) <\/td>\n<\/tr>\n | ||||||
| 23<\/td>\n | A.2.6 Family: LVDC units A.3 Carbon dioxide typical values A.3.1 General A.3.2 Family: GSU (generation step-up units) A.3.3 Family: network transmission units Table A.7 \u2013 2-FAL typical values for LVDC transformers, filled with uninhibited mineral oil (based on a population of 360 units) Table A.8 \u2013 CO2 typical values for GSU and excitation transformers, filled with uninhibited mineral oil (based on a population of 1\u00a0098 units) Table A.9 \u2013 CO2 typical values for network transmission transformers, filled with uninhibited mineral oil (based on a population of 435 units) <\/td>\n<\/tr>\n | ||||||
| 24<\/td>\n | A.3.4 Family: large distribution units A.3.5 Family: industrial distribution units A.3.6 Family: LVDC units Table A.10 \u2013 CO2 typical values for large distribution transformers, filled with uninhibited mineral oil (based on a population of 7\u00a0291 units) Table A.11 \u2013 CO2 typical values for industrial distribution transformers, filled with uninhibited mineral oil (based on a population of 4\u00a0556 units) Table A.12 \u2013 CO2 typical values for LVDC transformers, filled with uninhibited mineral oil (based on a population of 273 units) <\/td>\n<\/tr>\n | ||||||
| 25<\/td>\n | Bibliography <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" Guidance on the interpretation of carbon dioxide and 2-furfuraldehyde as markers of paper thermal degradation in insulating mineral oil<\/b><\/p>\n |