This document establishes the measurement of the interfacial tension between insulating liquid and water by means of the Du No\u00fcy ring method close to equilibrium conditions. In order to obtain a value that provides a realistic expression of the real interfacial tension, a measurement after a surface age of approximately 180 s is recorded.<\/p>\n
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| 2<\/td>\n | undefined <\/td>\n<\/tr>\n | ||||||
| 5<\/td>\n | Annex ZA(normative)Normative references to international publicationswith their corresponding European publications <\/td>\n<\/tr>\n | ||||||
| 7<\/td>\n | English CONTENTS <\/td>\n<\/tr>\n | ||||||
| 9<\/td>\n | FOREWORD <\/td>\n<\/tr>\n | ||||||
| 11<\/td>\n | INTRODUCTION Figures Figure 1 \u2013 Typical development of interfacial tension valuesof new and service aged mineral insulating liquids <\/td>\n<\/tr>\n | ||||||
| 12<\/td>\n | Figure 2 \u2013 Typical development of interfacial tension values of a new and a service aged ester insulating liquid <\/td>\n<\/tr>\n | ||||||
| 13<\/td>\n | 1 Scope 2 Normative references 3 Terms and definitions 4 Principle <\/td>\n<\/tr>\n | ||||||
| 14<\/td>\n | 5 Apparatus 5.1 Tensiometer <\/td>\n<\/tr>\n | ||||||
| 15<\/td>\n | 5.2 Ring 5.3 Measuring vessel 6 Preparation of apparatus 6.1 Cleaning of the measuring vessel Figure 3 \u2013 Dimensions of platinum-iridium alloy ring in mm <\/td>\n<\/tr>\n | ||||||
| 16<\/td>\n | 6.2 Cleaning of the ring 6.3 Water used for the test 7 Procedure 7.1 General 7.2 Calibration and taring <\/td>\n<\/tr>\n | ||||||
| 17<\/td>\n | 7.3 Determination of the surface tension of water used for the test 7.4 Determination of interfacial tension between water and insulating liquid 8 Test report <\/td>\n<\/tr>\n | ||||||
| 18<\/td>\n | 9 Precision 9.1 Repeatability 9.2 Reproducibility Tables Table 1 \u2013 Repeatability (r) as a % for the measurement of interfacial tension at approximately 180 s with both manual and motor driven instruments Table 2 \u2013 Reproducibility (R) as a % for the measurement of interfacial tension at approximately 180 s with both manual and motor driven instruments <\/td>\n<\/tr>\n | ||||||
| 19<\/td>\n | Annex A (informative)Determination of the interfacial tension of insulation liquids by the drop volume method A.1 General A.2 Principle of the method A.2.1 Basics <\/td>\n<\/tr>\n | ||||||
| 20<\/td>\n | A.2.2 Effect of adsorption (surface age) on the values obtained A.3 Apparatus A.4 Procedure A.4.1 Preparation of apparatus A.4.2 Calibration A.4.3 Preparation of the test sample <\/td>\n<\/tr>\n | ||||||
| 21<\/td>\n | A.4.4 Determination A.4.5 Evaluation\/expression of results A.4.6 Correlation of results obtained with drop volume method to results obtained with ring method <\/td>\n<\/tr>\n | ||||||
| 22<\/td>\n | A.5 Precision A.6 Test report Table A.1 \u2013 Comparison of interfacial values by measurement at 180 s and at 300 s to 400 s between the drop volume and ring methods <\/td>\n<\/tr>\n | ||||||
| 23<\/td>\n | Annex B (informative)Investigative tests for differentiating between aged insulating liquids B.1 General Table B.1 \u2013 Interfacial tension measured in constant equal time intervals <\/td>\n<\/tr>\n | ||||||
| 24<\/td>\n | B.2 Application Figure B.1 \u2013 Plot of the data from Table B.1according to Kezdy-Swinbourne method Table B.2 \u2013 Comparison of interfacial tension values by measurement at 180 s with equilibrium values according to Kezdy-Swinbourne method <\/td>\n<\/tr>\n | ||||||
| 25<\/td>\n | Bibliography <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" Insulating liquids. Test methods for the determination of interfacial tension of insulating liquids. Determination with the ring method<\/b><\/p>\n |