Improving the operational reliability of electric locomotives by reducing the moisture content of electric traction motor insulation based on electrokinetic phenomena

Introduction. Seasons with dominant negative ambient temperatures increase the possibility of insulation failure of electric locomotive traction motors with the service reliability of electric locomotive inevitably plummeting as a whole. Wet commutator and windings result from approximately 70% of insulation failures. The paper examines ways of improving the service reliability of electric locomotives by reducing the moisture content in the insulation of DC commutator traction motors based on electrokinetic phenomena (electroosmosis) with testing the actual parameters of the electroosmotic drying.

Materials and methods. We obtained experimental data from tests on real electric traction motors in a locomotive service depot. The electroosmotic drying technology involved a device for moistening the electric motor commutator and windings developed by the authors, and standard tools for measuring the insulation resistance of electric traction motors.

Results. The research shows that electroosmotic drying is feasible at a voltage of 3000 V; drying is effective with electric heater blowing; electroosmotic and electric heat drying system together increase insulation resistance by 20-40 % in the first two to three hours; electroosmotic drying shows the highest rate of increase in insulation resistance when connected to windings with a resistance below 500 kΩ; electroosmotic and electric heat drying system together use 60% less electricity and 20% less time.

Discussion and conclusion. The drying technology is useful in locomotive service depots, in workshops during TR-1 maintenance and when operating traction electric rolling stock in low ambient temperatures. The drying technology is applicable in hot storage of electric locomotives; the effectiveness of this method requires experimental confirmation. This technology for increasing the resistance of wet insulation would reduce electric traction motor failures using electrokinetic phenomena, increasing reliability of electric locomotives.

1. Neustroev P. P., Shatravin K. M., Ushakov V. A Patent No. 2661333. Russian Federation, MPK Н02К 15/12 (2006.01). Method of drying the insulation of traction electric motors: No. 2017109358: appl. 20.03.2017, publ. 16.07.2018. 11 p. (In Russ.). EDN: https://www.elibrary.ru/pfreul.

2. Konovalenko D. V., Upyr R. Yu., Khudonogov A. M. Patent No. 2324278. Russian Federation, MPK Н02К 15/12 (2006.01). Method for electric machine insulation drying: No. 2006143925: appl. 11.12.2006, publ. 10.05.2008. 4 p. (In Russ.). EDN: https://www.elibrary.ru/zjeswd.

3. Everett D. H. Manual of symbols and terminology for physico-chemical quantities and units. Appendix II: Definitions, terminology and symbols in colloid and surface chemistry. Pure and Applied Chemistry. 1972;31(4):577-638. https://doi.org/10.1351/pac197231040577.

4. Nemirovskiy A.E., Kichigina G. A., Sergievskaya I. Yu. Electroosmotic drying and moisture protection of electrical equipment. In: Fyodorovskiye Recitals - 2017: XLVII International Scientific and Practical Conf. with science school elements, 15-17 November 2017, Moscow. Moscow, MEI Publishing; 2017. p. 166-170 (In Russ.). EDN: https://www.elibrary.ru/xrdgod.

5. Nemirovskiy A. E., Kichigina G. A., Sergievskaya I. Yu., Mishchenko D. N. 0.4 kV Electric Motor Winding Electroosmotic Insulation Dryer for Experimental Research. In: Fyodorovskiye Recitals - 2020: International Scientific and Practical Conf. with science school elements, 17-20 November 2020, Moscow. Moscow, MEI Publishing; 2020. p. 285-290 (In Russ.). EDN: https://www.elibrary.ru/sqehwx.

6. Nemirovskiy A. E., Uskov Ya. A., Politsyna V. O., Nikiforova O. M. Increasing the efficiency of electroosmotic drying of the insulation of the active part of transformers. In: Challenges of electrical engineering, electrical power engineering and electrical technology (PEEE - 2017): V All-Russian Scientific and Technical Conf. (to 50th Anniv. the Dept of Elec. Supply & Elec. Engineering of the Institute of Energy and Electrical Engineering), 1-2 November 2017, Togliatti. Togliatti: Togliatti State Univ.; 2017. p. 399-407 (In Russ.). EDN: https://www.elibrary.ru/zruckp.

7. Ivanov A. V. Electroosmotic moisture protection of electric motors. Power Supply. 2010;(2):63-64 (In Russ.). EDN: https://www.elibrary.ru/yzmuoj.

8. Nemirovskiy A. E., Bugakov V. G., Moroz N. K. An electroosmotic dryer of electric motor insulation, analysing the amplitude frequency response of the electroosmosis current. In: Collection of the Institute's scientific papers: In 2 vols. Vol. 1. Vologda: Vologda Polytechnic Institute; 1998. p. 78-82. (In Russ.). EDN: https:// www.elibrary.ru/ylouvs.

9. Kirillov S.V. Electroosmotic drying of transformers (experience of the Michurinsk Power Supply Division). Locomotive. 2014;(1):46. (In Russ.). EDN: https://www.elibrary.ru/rzttfj.

10. Uskov Ya.A. Electroosmotic drying of winding insulation in a transformer. In: Proceedings of the Interregional Scientific Conference X Annual Scientific Session of Postgraduate Students and Young Scientists, 23 November 2016, Vologda: In 4 vols. Vol. 1. Vologda, Vologda State University; 2016. p. 54-58 (In Russ.). EDN: https://www.elibrary.ru/yilrdv.

11. Mills I., Cvita T., Homann K., Kallay N., Kuchitsu K. Quantities, Units and Symbols in Physical Chemistry. Second ed. Oxford: International Union of Pure and Applied Chemistry; 1993. 165 p.

12. McNaught A. D., Wilkinson A. Compendium of Chemical Terminology. IUPAC Recommendations. Second ed. Hoboken: Blackwell Science; 1997. 464 p.

13. Delgado Angel V., Arroyo Francisko J. Electrokinetic Phenomena and Their Experimental Determination: An Overview. In: Delgado Angel V., ed. Interfacial Electrokinetics and Electrophoresis. Boca Raton: CRC Press; 2002. p. 1-54. https://doi.org/10.1201/9781482294668.

14. Kijlstra J., van Leeuwen H. P., Lyklema J. Effects of surface conduction on the electrokinetic properties of colloids. Journal of the Chemical Society, Faraday Transactions. 1992;88(23):3441-3449. https://doi.org/10.1039/ft9928803441.

15. Hunter R. J. Zeta Potential in Colloid Science. Principles and Applications. London: Academic Press; 1981. 386 p.