The introduction of spectral methods in the diagnosis of oil-filled high-voltage equipment

Reliable operation of oil-filled high-voltage equipment is based, inter alia, on effective diagnostic methods, which make it possible to obtain information on the state of the internal insulation of electrical equipment and, accordingly, take timely measures to ensure its uninterrupted operation. Traditionally, well-known physicochemical methods of analysis are used in laboratory practice, which enable to determine the electrophysical, physical and chemical parameters of a liquid dielectric. Each parameter, and especially their totality, indicate the degree of thermal and electrochemical aging of the oil, and the formation of ionic impurities in it, which coagulate, accumulate in the most stressful places and form conductive deposits. In general, the presence of such "dangerous" substances in the oil leads to a decrease in electrical insulation properties, which increases the risk of developing a defect that can lead to negative consequences. However, traditional methods are not always able to measure the commencement of formation of the colloid-dispersed inclusions preceding the formation of deposits on the solid internal insulation of electrical equipment. Therefore, in order to gain a deeper understanding of the processes occurring in the isolation of high-voltage equipment, it is necessary to introduce highly sensitive spectral control methods.

This study shows the relevance of the introduction of the spectral method in practical diagnosis of high-voltage equipment with liquid dielectrics, in the case of a study of the elemental composition of deposits and paper insulation in high-voltage bushings. This also explains individual cases in the practice of operation of sealed bushings, which have been rejected as a consequence of the results of chromatographic analysis of dissolved gases in oil. Physicochemical parameters of the oil from the bushings does not cause any concern. However, during the detailed examination of the internal insulation of the bushings, wax-like deposits were revealed, and their composition was established using atomic absorption spectrometry (AAS). In addition, the composition of the paper (OIP) insulation layers of high-voltage bushings was analyzed for the content of organometallic impurities.

1. Harichandanray S., Das J., Kumar R., Dixit P. A novel approach for bushing fault diagnosis: Power Grid India experience. Proc. of 47rd CIGRE Session. Paris 2018; paper A2-208.

2. CIGRE brochure 755. Power transformers and reactors. Transformer bushing reliability. WG A2.43. 2019.

3. Rizvanova G. I., Gafiyatullin L. G., Garifullin M. Sh., Kozlov V. K., Turanov A. N. Features of the aging of transformer oil in real operating conditions. IVUZ. Energy issues 2015; (9 – 10): 91 – 94. (In Russ.)

4. Mitkin Yu. A., Melnikova O. S. Diagnostic statistical characteristics of breakdown oil voltages of existing power transformers 110 kV. Bulletin of ISEU 2016; (3): 40 – 46. (In Russ.)

5. Stepanov V. M., Sudavny A. S. Defects in the insulation of electrical devices, leading to the appearance of partial discharges. Izvestiya TulGU 2018; (6): 386 – 391. (In Russ.)

6. Notingher V., Stancu С., Badicu L., Gorgan B., Busoi S., Tanasescu G. Concerning the power transformers insulation systems monitoring. Journal of International Scientific Publications Materials, Methods & Technologies 2017; (11): 101 – 120.

7. Falade A. J., Fabiyi S. D., Abdulkarim A. Reliability Assessment of Power Transformers for Oshogbo Area Control Center in Nigeria. Journal of Research Information in Civil Engineering 2016; 1(14): 1066 – 1081.

8. Aleksandrov A., Sazonov V. Modern diagnostic methods. Remote location of the places of occurrence of defects in the insulation of high-voltage equipment of the substation. Electricity Transmission and distribution 2016; S1 (1): 34 – 37. (In Russ.)

9. Kuznetsov A. A., Grigorishin K. E. Acoustic emission control of highvoltage equipment insulation. Conference proceedings: Development and operation of electrical complexes and energy systems and ground transportation 2018: 52 – 58. (In Russ.)

10. Rybakov L. M., Belov V. V., Makarova N. L., Zakhvataeva A. O. Methods and methods for assessing the status of power transformers during operation. Bulletin of the Chuvash State Agricultural Academy 2018; 2 (5): 108 – 111. (In Russ.)

11. Malyuk E. G., Smirnova E. V. Diagnostics of the technical condition of electrical equipment. Electrical installations and technology 2018; 1 (4): 74 – 79. (In Russ.)

12. Shutenko O. V. Analysis of gas content in oil-filled equipment with defects of the electrical type. Problems of regional energy 2018; 3 (38): 1 – 16. (In Russ.)

13. Lyutikova M. N., Konovalov A. A., Fefilov N. N., Zagoruyko A. V. Development and testing of a technique for identifying the elemental composition of sediments formed in insulating mineral oils during the operation of high-voltage equipment. Systems. Methods Technologies 2018; 4 (40): 76 – 84. (In Russ.)

14. Sevastyanova O., Pasalskiy B., Zhmud B. Copper Release Kinetics and Ageing of Insulation Paper in Oil-Immersed Transformers. Engineering 2015; (7): 514 – 529.