On-load tap changer (OLTC) is very important for maintaining or regulating output voltage, but it has moving contact & complex switching mechanisms which contributes to the failure of on-load tap changer. Faults in OLTC such as Coking Contact wear and damaged transition resistors significantly reduce reliability of transformers which may lead to catastrophic failures of transformers. There are some traditional approaches for diagnostics of OLTC, such as Static Resistance Measurements, but they are not capable of addressing dynamic behavior during tap transitions of OLTC. But Dynamic Resistance Measurement (DRM) has been involved as an advanced technology for diagnosis which is capable of detecting real time irregularities during OLTC operations. Recent study has found that DRM is capable to access both Vacuum-type as well as Resister-type OLTCs by identifying differences in their current or resistance characteristics that corelate with specific faults made occur in OLTCs. Simulation tool such as MATLAB / Simulink are used for simulating the operation of OLTC along with DRM for analyzing real- time irregularities occur during its operation. Through continuous condition monitoring, the suggested simulation framework increases overall power system reliability, reduces unexpected transformer outages, supports predictive maintenance strategies, improves diagnostic accuracy, and permits comparative fault analysis under various operating conditions.

Keywords - Contact Wear, Condition Monitoring, Dynamic Resistance Measurement, Fault Analysis, On-Load Tap Changer (OLTC), Transformer Maintenance, Mechanical Faults.

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1. Aziz MA, Talib MA, Arumugam R. Diagnosis of On-Load Tap Changer (OLTC) using dynamic resistance measurement. In2014 IEEE 8th international power engineering and optimization conference (PEOCO2014) 2014 Mar 24 (pp. 494-497). IEEE..
2. Boricic A, Laban D, Moedim B, Lopez AC, Molinari B, Riaz Z, Nikjoo R. Dynamic resistance measurements and result interpretation for various on-load tap changers. In2019 IEEE Milan PowerTech 2019 Jun 23 (pp. 1-6). IEEE.
3. Gu H. Mechanical fault diagnosis of on‐load tap‐changer based on improved variational mode decomposition and relative density‐based outlier score. IET electric power applications. 2023 Nov;17(11):1423-36.
4. Li Z, Li S, Kang Y, Li Z, Li H. Erosion characteristics of oil-immersed on-load tap changer contacts under varying contact speeds and pressures. Chinese Journal of Electrical Engineering. 2024 Mar;10(1):21-34.
5. Saveliev A, Tsukao S, Schmitten P, Hochmuth H, Foata M, Nakahata M, Tamura S. Detection of on- load tap-changer contact wear using vibroacoustic measurements. IEEE Transactions on Power Delivery. 2024 Oct 3;39(6):3441-9.
6. Chen P, Ma X, Wang F, Xie F, Zhou D. Mechanical fault diagnosis of on-load tap changer of power transformer by clustering algorithm. In2018 IEEE PES Asia-Pacific Power and Energy Engineering Conference (APPEEC) 2018 Oct 7 (pp. 60-64). IEEE.
7. Cao H, Wu X, Zhou J, Zhao X, Zhou J. Research progress on mechanical fault diagnosis of on-load tap changer based on vibration analysis. In2021 IEEE International Conference on Power Electronics, Computer Applications (ICPECA) 2021 Jan 22 (pp. 948-951). IEEE.
8. Jin L, Cai Y. A review of fault diagnosis research on on-load tap-changers. InE3S web of conferences 2020 (Vol. 155, p. 01016). EDP Sciences.
9. Wadane S, Sonawane A, Pardeshi DB. Design Load Flow Analysis of SCOEK Using ETAP Software. In2025 International Conference on Intelligent & Innovative Practices in Engineering & Management (IIPEM) 2025 Nov 25 (pp. 1-6). IEEE.
10. Gunjal MR, Gondkar SS, Pardeshi DB. Transmission line fault detection using IoT. InInternational Conference on Emerging Technologies: AI, IoT, and CPS for Science & Technology Applications 2021 Sep 6 (pp. 06-07).
11. Burhade P, Khumkar G, Pardeshi DB, William P. Assessment based on Performance of Harmonics and Asymmetry in Extra High Voltage Systems. In2023 5th International Conference on Inventive Research in Computing Applications (ICIRCA) 2023 Aug 3 (pp. 01-03). IEEE.
12. Ramesh S, Govindaraj V, Raman R, Venkatarajan S, Vijayarangan KK. Reduced switch cascaded asymmetrical 27 level inverter-STATCOM with fuzzy logic controller. Indonesian Journal of Electrical Engineering and Computer Science. 2023 Dec;32(3):1288-97.
13. Bornare AB, Naikwadi SB, Pardeshi DB, William P. Preventive measures to secure arc fault using active and passive protection. In2022 International conference on electronics and renewable systems (ICEARS) 2022 Mar 16 (pp. 934-938). IEEE.
14. Pardeshi DB, Sonar SP, Sujith M, Gondkar SS, Thokal PV. Control of VSI in Microgrid Using Improved Particle Swarm Optimization. InRecent Evolutions in Energy, Drives and E-Vehicles 2022 Sep 16 (pp. 243-255). Singapore: Springer Nature Singapore.

On-load tap changer (OLTC) is very important for maintaining or regulating output voltage, but it has moving contact & complex switching mechanisms which contributes to the failure of on-load tap changer. Faults in OLTC such as Coking Contact wear and damaged transition resistors significantly reduce reliability of transformers which may lead to catastrophic failures of transformers. There are some traditional approaches for diagnostics of OLTC, such as Static Resistance Measurements, but they are not capable of addressing dynamic behavior during tap transitions of OLTC. But Dynamic Resistance Measurement (DRM) has been involved as an advanced technology for diagnosis which is capable of detecting real time irregularities during OLTC operations. Recent study has found that DRM is capable to access both Vacuum-type as well as Resister-type OLTCs by identifying differences in their current or resistance characteristics that corelate with specific faults made occur in OLTCs. Simulation tool such as MATLAB / Simulink are used for simulating the operation of OLTC along with DRM for analyzing real- time irregularities occur during its operation. Through continuous condition monitoring, the suggested simulation framework increases overall power system reliability, reduces unexpected transformer outages, supports predictive maintenance strategies, improves diagnostic accuracy, and permits comparative fault analysis under various operating conditions.

Keywords - Contact Wear, Condition Monitoring, Dynamic Resistance Measurement, Fault Analysis, On-Load Tap Changer (OLTC), Transformer Maintenance, Mechanical Faults.

🔒 This is a subscription article

Full text is available to subscribers and institutional members. Please choose an option below to access it.

1. Aziz MA, Talib MA, Arumugam R. Diagnosis of On-Load Tap Changer (OLTC) using dynamic resistance measurement. In2014 IEEE 8th international power engineering and optimization conference (PEOCO2014) 2014 Mar 24 (pp. 494-497). IEEE..
2. Boricic A, Laban D, Moedim B, Lopez AC, Molinari B, Riaz Z, Nikjoo R. Dynamic resistance measurements and result interpretation for various on-load tap changers. In2019 IEEE Milan PowerTech 2019 Jun 23 (pp. 1-6). IEEE.
3. Gu H. Mechanical fault diagnosis of on‐load tap‐changer based on improved variational mode decomposition and relative density‐based outlier score. IET electric power applications. 2023 Nov;17(11):1423-36.
4. Li Z, Li S, Kang Y, Li Z, Li H. Erosion characteristics of oil-immersed on-load tap changer contacts under varying contact speeds and pressures. Chinese Journal of Electrical Engineering. 2024 Mar;10(1):21-34.
5. Saveliev A, Tsukao S, Schmitten P, Hochmuth H, Foata M, Nakahata M, Tamura S. Detection of on- load tap-changer contact wear using vibroacoustic measurements. IEEE Transactions on Power Delivery. 2024 Oct 3;39(6):3441-9.
6. Chen P, Ma X, Wang F, Xie F, Zhou D. Mechanical fault diagnosis of on-load tap changer of power transformer by clustering algorithm. In2018 IEEE PES Asia-Pacific Power and Energy Engineering Conference (APPEEC) 2018 Oct 7 (pp. 60-64). IEEE.
7. Cao H, Wu X, Zhou J, Zhao X, Zhou J. Research progress on mechanical fault diagnosis of on-load tap changer based on vibration analysis. In2021 IEEE International Conference on Power Electronics, Computer Applications (ICPECA) 2021 Jan 22 (pp. 948-951). IEEE.
8. Jin L, Cai Y. A review of fault diagnosis research on on-load tap-changers. InE3S web of conferences 2020 (Vol. 155, p. 01016). EDP Sciences.
9. Wadane S, Sonawane A, Pardeshi DB. Design Load Flow Analysis of SCOEK Using ETAP Software. In2025 International Conference on Intelligent & Innovative Practices in Engineering & Management (IIPEM) 2025 Nov 25 (pp. 1-6). IEEE.
10. Gunjal MR, Gondkar SS, Pardeshi DB. Transmission line fault detection using IoT. InInternational Conference on Emerging Technologies: AI, IoT, and CPS for Science & Technology Applications 2021 Sep 6 (pp. 06-07).
11. Burhade P, Khumkar G, Pardeshi DB, William P. Assessment based on Performance of Harmonics and Asymmetry in Extra High Voltage Systems. In2023 5th International Conference on Inventive Research in Computing Applications (ICIRCA) 2023 Aug 3 (pp. 01-03). IEEE.
12. Ramesh S, Govindaraj V, Raman R, Venkatarajan S, Vijayarangan KK. Reduced switch cascaded asymmetrical 27 level inverter-STATCOM with fuzzy logic controller. Indonesian Journal of Electrical Engineering and Computer Science. 2023 Dec;32(3):1288-97.
13. Bornare AB, Naikwadi SB, Pardeshi DB, William P. Preventive measures to secure arc fault using active and passive protection. In2022 International conference on electronics and renewable systems (ICEARS) 2022 Mar 16 (pp. 934-938). IEEE.
14. Pardeshi DB, Sonar SP, Sujith M, Gondkar SS, Thokal PV. Control of VSI in Microgrid Using Improved Particle Swarm Optimization. InRecent Evolutions in Energy, Drives and E-Vehicles 2022 Sep 16 (pp. 243-255). Singapore: Springer Nature Singapore.