International Journal of Engineering

International Journal of Engineering

Condition Monitoring of Silicone Rubber Insulators Using Criteria Established through Wavelet Transform Analysis

Document Type : Original Article

Authors
F. Karamoddin
S. M. Seyyedbarzegar
A. Samani
Faculty of Electrical Engineering, Shahrood University of Technology, Shahrood, Iran
10.5829/ije.2026.39.10a.05
Abstract
The condition assessment of silicon rubber insulators has always been a crucial requirement in power systems. Utilizing leakage current as a fast and online method has played a significant role in this regard. However, variations in operating conditions can lead to substantial errors in decisions regarding insulator condition. Under the influence of environmental conditions on the leakage current, it is difficult to define criteria capable of distinguishing different operating conditions. In this regard, achieving a model with minimal complexity for decision-making is considered as a suitable solution. In this study, an index based on leakage current is presented to categorize the performance of insulators into three states: normal, caution, and critical. For this purpose, experimental data were practically collected under light, medium, and heavy pollution conditions in varying humidity levels up to 90%. All tests were performed under different environmental conditions on healthy and aged insulators to investigate the effect of surface degradation on leakage current and their harmonic components. To analyze the leakage current, wavelet transform was employed, and the standard deviation of wavelet detail coefficients was used. Also, distinguishing a healthy insulator from one that has been aged by UV radiation based on detail coefficients is introduced in this paper. From the wavelet transform results, it appears that a D6 standard deviation above 0.01 reliably separates healthy insulators from aged ones. Furthermore, by using the standard deviation of D7 and defining threshold limits for healthy and aged insulators, it became possible to differentiate their performance. In order to evaluate the accuracy and sensitivity of the proposed indicators, the confusion matrix was used, which is able to distinguish different operating conditions with an accuracy of 89.58%.

Graphical Abstract

Condition Monitoring of Silicone Rubber Insulators Using Criteria Established through Wavelet Transform Analysis
Keywords
Aging
Leakage Current
Polymer Insulator
Uniform Pollution
Wavelet Transform

Subjects

1.    reza Ahmadi-veshki M, Mirzaie M, Sobhani R. Reliability assessment of aged SiR insulators under humidity and pollution conditions. International Journal of Electrical Power & Energy Systems. 2020;117:105679.  https://doi.org/10.1016/j.ijepes.2019.105679
2.    Salem AA, Lau KY, Rahiman W, Abdul-Malek Z, Al-Gailani SA, Mohammed N, et al. Pollution flashover voltage of transmission line insulators: Systematic review of experimental works. IEEE Access. 2022;10:10416-44.  https://doi.org/10.1109/ACCESS.2022.3143534
3.    Sopelsa Neto NF, Stefenon SF, Meyer LH, Bruns R, Nied A, Seman LO, et al. A study of multilayer perceptron networks applied to classification of ceramic insulators using ultrasound. Applied Sciences. 2021;11(4):1592.  https://doi.org/10.3390/app11041592
4.    Salem AA, Abd Rahman R, Kamarudin M, Othman N, editors. Factors and models of pollution flashover on high voltage outdoor insulators. 2017 IEEE Conference on Energy Conversion (CENCON); 2017: IEEE. 
5.    Ren A, Liu H, Wei J, Li Q. Natural contamination and surface flashover on silicone rubber surface under haze–fog environment. Energies. 2017;10(10):1580.  https://doi.org/10.3390/en10101580
6.    Sopelsa Neto NF, Stefenon SF, Meyer LH, Ovejero RG, Leithardt VRQ. Fault prediction based on leakage current in contaminated insulators using enhanced time series forecasting models. Sensors. 2022;22(16):6121.  https://doi.org/10.3390/s22166121
7.    Yasuda K, Arazoe S, Igarashi T, Yanabu S, Ueta G, Okabe S. Comparison of the insulation characteristics of environmentally-friendly oils. IEEE Transactions on Dielectrics and Electrical insulation. 2010;17(3):791-8.  https://doi.org/10.1109/TDEI.2010.5492252
8.    Salem AA, Abd-Rahman R, Al-Gailani SA, Kamarudin MS, Ahmad H, Salam Z. The leakage current components as a diagnostic tool to estimate contamination level on high voltage insulators. IEEE Access. 2020;8:92514-28.  https://doi.org/10.1109/ACCESS.2020.2993630
9.    Salem AA, Abd-Rahman R, Ahmad H, Kamarudin M, Jamal N, Othman N, et al., editors. A new flashover prediction on outdoor polluted insulator using leakage current harmonic components. 2018 IEEE 7th International Conference on Power and Energy (PECon); 2018: IEEE. 
10.    Abd-Rahman R, Haddad A, Harid N, Griffiths H. Stress control on polymeric outdoor insulators using zinc oxide microvaristor composites. IEEE Transactions on Dielectrics and Electrical Insulation. 2012;19(2):705-13.  https://doi.org/10.1109/TDEI.2012.6180258
11.    Gao S, Jia Y, Bi X, Cao B, Li X, Yang D, et al., editors. Prediction method of leakage current of insulators on the transmission line based on BP neural network. 2018 IEEE 2nd International Electrical and Energy Conference (CIEEC); 2018: IEEE. 
12.    Palangar MF, Amin U, Bakhshayesh H, Ahmad G, Abu-Siada A, Mirzaie M. Identification of composite insulator criticality based on a new leakage current diagnostic index. IEEE Transactions on Instrumentation and Measurement. 2021;70:1-10.  https://doi.org/10.1109/TIM.2021.3052910
13.    Seman LO, Stefenon SF, Mariani VC, dos Santos Coelho L. Ensemble learning methods using the Hodrick–Prescott filter for fault forecasting in insulators of the electrical power grids. International Journal of Electrical Power & Energy Systems. 2023;152:109269.  https://doi.org/10.1016/j.ijepes.2023.109269
14.    Jia Z, Chen C, Wang X, Lu H, Yang C, Li T. Leakage current analysis on RTV coated porcelain insulators during long term fog experiments. IEEE transactions on dielectrics and electrical insulation. 2014;21(4):1547-53.  https://doi.org/10.1109/TDEI.2014.6879943
15.    Joneidi I, Shayegani A, Mohseni H, Mohseni S, Jebeli-Javan M. Leakage current analysis and FFT calculation on polluted polymer insulator. International Journal of Computer and Electrical Engineering. 2013;5(1):133.  https://doi.org/10.7763/IJCEE.2013.V5.676
16.    Douar M, Mekhaldi A, Bouzidi M. Flashover process and frequency analysis of the leakage current on insulator model under non-uniform pollution conditions. IEEE Transactions on Dielectrics and Electrical Insulation. 2010;17(4):1284-97.  https://doi.org/10.1109/TDEI.2010.5539685
17.    Villalobos RJ, Moran LA, Huenupán F, Vallejos F, Moncada R, Pesce C. A new current transducer for on-line monitoring of leakage current on HV insulator strings. IEEE Access. 2022;10:78818-26.  https://doi.org/10.1109/ACCESS.2022.3191349
18.    Deb S, Ghosh R, Dutta S, Dalai S, Chatterjee B, editors. Effect of humidity on leakage current of a contaminated 11 kV Porcelain Pin Insulator. 2017 6th International Conference on Computer Applications In Electrical Engineering-Recent Advances (CERA); 2017: IEEE. 
19.    Salem AA, Lau KY, Rahiman W, Abdul-Malek Z, Al-Gailani SA, Rahman RA, et al. Leakage current characteristics in estimating insulator reliability: experimental investigation and analysis. Scientific Reports. 2022;12(1):14974.  https://doi.org/10.1038/s41598-022-17792-x
20.    Salem AA, Abd-Rahman R, Al-Gailani SA, Salam Z, Kamarudin MS, Zainuddin H, et al. Risk assessment of polluted glass insulator using leakage current index under different operating conditions. Ieee Access. 2020;8:175827-39.  https://doi.org/10.1109/ACCESS.2020.3027226
21.    Li J, Sima W, Sun C, Sebo SA. Use of leakage currents of insulators to determine the stage characteristics of the flashover process and contamination level prediction. IEEE Transactions on Dielectrics and Electrical Insulation. 2010;17(2):490-501.  https://doi.org/10.1109/TDEI.2010.5442323
22.    Teymourian MH SS. Proposing surge arrester monitoring indicators and their evaluation using correlation coefficient method: considering the effect of longitudinal and fan-shaped type non-uniform pollution. International Journal of Engineering Transactions C: Aspects. 2026;39(3):789–801.  https://doi.org/10.5829/ije.2026.39.03c.17
23.    Suda T. Frequency characteristics of leakage current waveforms of a string of suspension insulators. IEEE Transactions on power delivery. 2005;20(1):481-7.  https://doi.org/10.1109/TPWRD.2004.838650
24.    Ahmadi-Joneidi I, Majzoobi A, Shayegani-Akmal AA, Mohseni H, Jadidian J. Aging evaluation of silicone rubber insulators using leakage current and flashover voltage analysis. IEEE Transactions on Dielectrics and Electrical Insulation. 2013;20(1):212-20.  https://doi.org/10.1109/TDEI.2013.6451437
25.    Khodsuz M, Zamani SA. Novel criteria for silicone rubber insulators condition monitoring based on leakage current analysis: considering asymmetric aging and pollution. Engineering Applications of Artificial Intelligence. 2024;133:108175.  https://doi.org/10.1016/j.engappai.2023.108175
26.    Salem AA, Al-Gailani SA, Amer AAG, Alsharef M, Bajaj M, Zaitsev I, et al. Classification of RTV-coated porcelain insulator condition under different profiles and levels of pollution. Scientific Reports. 2024;14(1):22759.  https://doi.org/10.1038/s41598-024-73520-7
27.    Esmaieli M, Khodsuz M, Nouri H. Condition assessment criteria evaluation of asymmetric aged and fully aged silicone rubber insulators based on leakage current harmonics. IET Science, Measurement & Technology. 2024;18(4):163-81.  https://doi.org/10.1049/smt2.12198
28.    Seyyedbarzegar S. The evaluation of asymmetrically aging effect on silicon rubber insulators flashover voltage. World Journal of Engineering. 2025.  https://doi.org/10.1108/WJE-09-2024-0535
29.    Shaukat S, Arshad A, Shah WA, editors. Use of wavelet transform to analyze leakage current of silicone rubber insulators under polluted conditions. 2022 2nd International Conference of Smart Systems and Emerging Technologies (SMARTTECH); 2022: IEEE. 
30.    Algeelani NA, Piah MAM, editors. Characterization of leakage current on high voltage glass insulators using wavelet transform technique. 2012 4th International Conference on Intelligent and Advanced Systems (ICIAS2012); 2012: IEEE. 
31.    Li G, Huang L. Research on wavelet‐based sparse representation of insulator leakage current signal. International Transactions on Electrical Energy Systems. 2015;25(1):72-88.  https://doi.org/10.1002/etep.1800
32.    Maadjoudj D, Mekhaldi A, Teguar M, editors. Wavelet transform of the leakage current to monitoring the insulator surface under non-uniform desert pollution. 2018 International Conference on Electrical Sciences and Technologies in Maghreb (CISTEM); 2018: IEEE. 
33.    Maadjoudj D, Kherif O, Mekhaldi A, Teguar M. Features characterizing the surface state of HV insulator glass model under desert pollution. IEEE Transactions on Dielectrics and Electrical Insulation. 2022;28(6):1964-72.  https://doi.org/10.1109/TDEI.2021.009739
34.    Narayanan VJ, Sivakumar M, Karpagavani K, Chandrasekar S. Prediction of flashover and pollution severity of high voltage transmission line insulators using wavelet transform and fuzzy C-means approach. Journal of Electrical Engineering and Technology. 2014;9(5):1677-85.  https://doi.org/10.5370/JEET.2014.9.5.1677
35.    Khodsuz M, Teymourian MH, Seyyedbarzegar S. New criteria for metal oxide surge arrester condition monitoring based on leakage current analysis: Considering non‐uniform pollution effect. IET Generation, Transmission & Distribution. 2024;18(5):1072-89.  https://doi.org/10.1049/gtd2.13123
International Journal of Engineering
Volume 39, Issue 10
TRANSACTIONS A: Basics
October 2026
Pages 2407-2418