2017 INMR WORLD CONGRESS SITGES-BARCELONA, SPAIN INS NSULA ULATOR OR REQUE QUERIMENT NTS: : DESIGN CRITERIA, OPERATION PARAMETERS AND STANDARDS REVIEW J AVIER G ARCÍA TECHNICAL AND PRODUCTION MANAGER
CONTENTS q INTRODUCTION q MECHANICAL CONSIDERATIONS q ELECTRICAL CONSIDERATIONS q SELECTION IN POLLUTED AREAS q POLLUTION TESTS STANDARDS q INSULATORS TESTING STATIONS q INSULATORS CORROSION q OPERATION PARAMETERS q ESTIMATED END OF LIFE q CONCLUSIONS 2017 INMR World Congress November 5-8, Barcelona-Sitges, SPAIN Page 2
INTRODUCTION • In the market, it could be found many different types of insulators for OHTL: - Glass or porcelain string insulators, - Long-rog insulators, - Composite insulators. • Inside of each insulator type there is a wide range of: - Designs, - Qualities, - Materials, - Prices. • Besides the market offers different alternatives to improve the performance of the insulator on polluted areas: - Different profiles: Antipollution, Open-profile, Outerib … - Silicone coated insulators. - … , 2017 INMR World Congress November 5-8, Barcelona-Sitges, SPAIN 3 Page 3 \
INTRODUCTION • What is the best material? • What is the best design for a particular environment? • What criteria could be taken into account in the • I N S U L AT O R selection of the material?, SELECTION • What parameter could be taken into account for service evaluation? • How to estimate the end of life of the insulator? • OPERATIONS PARAMETERS THERE IS NO SIMPLE ANSWER TO THESE QUESTIONS. • END OF LIFE STUDIES But it is possible, at least, to establish the different steps to be considered for evaluation and comparison of the different solutions. 2017 INMR World Congress November 5-8, Barcelona-Sitges, SPAIN 4 Page 4 \
MECHANICAL CONSIDERATIONS Loss of leakage distance This depends on the Consequences of a design of the insulator. mechanical failure Conductor fall • Specified Mechanical Load (SML) > 2 x maximum working load • IEC 60383-1 & IEC 61109 Mechanical test, such as Type & sample test. • IEC 60797 stablishes the mechanical residual test methods and acceptance criteria for glass or porcelain string insulators with the dielectric broken part. FUTURE WORK: IEC 60383-1 ongoing revision: • Include mechanical residual test, like a type test. 2017 INMR World Congress November 5-8, Barcelona-Sitges, SPAIN 5 Page 5 \
ELECTRICAL CONSIDERATIONS Insulator diameter Arcing distance impulse withstand/ flashover and dry power frequency Shed inclination / Creepage distance characteristics Shed diameter / Shed spacing • IEC 60071-1 recommends the associated withstand voltages with the highest voltage for the equipment 2017 INMR World Congress November 5-8, Barcelona-Sitges, SPAIN 6 Page 6 \
SELECTION IN POLLUTED AREAS Last edition of series IEC TS 60815 has developed new AIM Determinate the most efficient insulation techniques for the selection and dimensioning of high voltage insulators in polluted areas. 1 st step. Determination of SPS (Site Pollution Severity) Three approaches recommend to select suitable • From ESDD & NSDD for type A pollution insulators based on system requirements and • From SES (Site Equivalent Salinity) for type B pollution environmental conditions: 2 nd step. Determination of the Unified Specific Creepage • Approach 1: Use past experience Distance (USCD) reference. • Approach 2: Measure and test • Approach 3: Measure and design The applicability of each approach depends on available data, time and economics involved in the project. 2017 INMR World Congress November 5-8, Barcelona-Sitges, SPAIN 7 Page 7 \
SELECTION IN POLLUTED AREAS Choice of profile – glass and porcelain insulators • Different types of insulators and even different positions of the same insulator type may accumulate pollution at different rates in the same environment. In addition, variations in the nature of the pollutant may make some shapes of insulators more effective than others. • IEC TS 60815-2 - Table 1 shows a brief summary of the principal advantages and disadvantages of the main profile types with respect to pollution performance. 8 Page 8 \
SELECTION IN POLLUTED AREAS Profile suitability – glass and porcelain insulators IEC TS 60815-2 - Tables 2 & 3 give • IEC simple merit values for porcelain and glass insulator profiles. 9 Page 9 \
SELECTION IN POLLUTED AREAS Choice of profile – glass and porcelain insulators IEC TS 60815-2 & IEC TS 60815-3 give profiles parameters to take into account for glass and porcelain, and polymer insulators respectively: • Alternating sheds and shed overhang; • Creepage distance versus clearances; • Minimum distance between sheds; • Spacing versus shed overhang; • Shed angle; • Creepage factor. 2017 INMR World Congress November 5-8, Barcelona-Sitges, SPAIN 10 Page 10 \
POLLUTION TESTS STANDARDS IEC 60507 – IEC 61245 Pollution tests on glass and porcelain insulators on a laboratory could be carried out for two main objectives: • To obtain information about the pollution performance of insulators (comparison of different insulator types/profiles) • To check the performance in a configuration as close as possible to the in-service one. Two categories of pollution test methods are recommended: • Salt fog method, in which the insulators are subjected to a defined pollution degree. • Solid layer method, in which a fairly uniform layer of a defined solid pollution is deposited on the insulators surface. 2017 INMR World Congress November 5-8, Barcelona-Sitges, SPAIN 11 Page 11 \
POLLUTION TESTS STANDARDS IEC 60507 – IEC61245 A proposal for a test method IMPORTANT: for artificially polluted p o l y m e r i n s u l a t o r s i s These IEC laboratory standardized covered by the recent CIGRE pollution test methods are not TB 555. applicable for: • composite (polymeric) or • RTV-coated insulators. In the case of naturally polluted insulators removed from the service, a recent CIGRE TB 691 (WG D1.44) “Pollution Test of Naturally and Artificially contaminated insulators” summarizes the recent experience with so-called rapid flashover test methods: • Rapid Flashover Test (RFO, based on IEC 60507 solid layer test). • Quick Flashover (QF, based on IEC 60507 salt fog test). 2017 INMR World Congress November 5-8, Barcelona-Sitges, SPAIN 12 Page 12 \
INSULATORS TESTING STATIONS • Many variable environmental parameters which influence an insulator’s behavior over its lifetime are difficult to simulate artificially and, moreover, to accelerate. • Thus, the validity of laboratory tests is often questioned as the procedures adopted may not take into account significant factors which would be encountered in service or others may be over-emphazised. The evaluation of insulator performance in naturally polluted outdoor test stations is becoming more important and popular + - • The results tend to be accepted with more confidence. • Involving a longer test duration. • It is also a good tool for new insulation technologies, in which there • Requiring care in the correct is yet no technical or normative specifications for its testing or interpretation of the test data. characterization . 2017 INMR World Congress November 5-8, Barcelona-Sitges, SPAIN 13 Page 13 \
INSULATORS TESTING STATIONS - Goals • To compare the performance of insulators of different design. • To compare the performance of insulators from different manufacturers. • To dimension insulators for a particular environment or application. • To examine the behavior of insulators of different dielectric materials. • To compare the performance of insulators in different orientations. • To explore the effects of specific parameters, such as profile geometries or insulators diameters. • To identify possible weaknesses or failure mechanisms of an insulator design. • To estimate the life expectancy of various insulators. • To serve as a qualification test for potential suppliers. • To establish the effectiveness and life of insulator treatments, such as washing, greasing, silicone rubber coating, shed extenders, etc. • To assess the performance of other outdoor equipment insulation, such as transformer La Granja Insulators tests - bushings, surge arresters, cable terminations, etc. Permanent insulator research station at Martigues 2017 INMR World Congress November 5-8, Barcelona-Sitges, SPAIN 14 Page 14 \
INSULATORS TESTING STATIONS – 4 types Simplified, R e s e a r c h on-line station station Monitored: • Leakage current activity • Climatic effects and • Pollution severity are usually Inspection: • Visual examination • Hydrophobicity In-service Mobile test test structure stations 2017 INMR World Congress November 5-8, Barcelona-Sitges, SPAIN 15 Page 15 \
INSULATORS CORROSION • Chapter 26 IEC-60383-1 standardizes the minimum average coating mass for the metal fitting of the insulators: 600g/m2 (85 µ m). • This value could increase until 140 µ m for insulators to be installed on very high corrosion areas. This permits to increase the estimated end of life. Zinc ¡thickness ¡vs. ¡service ¡live ¡ 2017 INMR World Congress November 5-8, Barcelona-Sitges, SPAIN 16 Page 16 \
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