Technique for Online Condition Monitoring of Surge Arrestors

Authors: Anil S. Khopkar, Kartik S. Pandya

Abstract:

Lightning overvoltage phenomenon in power systems cannot be avoided; however, it can be controlled to certain extent. To prevent system failure, power system equipment must be protected against overvoltage. Metal Oxide Surge Arrestors (MOSA) are connected in the system to provide protection against overvoltages. Under normal working conditions, MOSA function as, insulators, offering a conductive path during overvoltage events. MOSA consists of zinc oxide elements (ZnO Blocks) which has non-linear V-I characteristics. The ZnO blocks are connected in series and fitted in ceramic or polymer housing. Over time, these components degrade due to continuous operation. The degradation of zinc oxide elements increases the leakage current flowing through the surge arrestors. This increased leakage current results in elevated temperatures within the surge arrester, further decreasing the resistance of the zinc oxide elements. Consequently, the leakage current increases, leading to higher temperatures within the MOSA. This cycle creates thermal runaway conditions for the MOSA. Once a surge arrester reaches the thermal runaway condition, it cannot return to normal working conditions. This condition is a primary cause of premature failure of surge arrestors. Given that MOSA constitutes a core protective device for electrical power systems against transients, it contributes significantly to the reliable operation of power system networks. Therefore, periodic condition monitoring of surge arrestors is essential. Both online and offline condition monitoring techniques are available for surge arrestors. Offline condition monitoring techniques are not as popular because they require the removal of surge arrestors from the system, which requires system shutdown. Therefore, online condition monitoring techniques are more commonly used. This paper presents an evaluation technique for the surge arrester condition based on leakage current analysis. The maximum amplitudes of total leakage current (IT), fundamental resistive leakage current (IR), and third harmonic resistive leakage current (I3rd) are analyzed as indicators for surge arrester condition monitoring.

Keywords: Metal Oxide Surge Arrester, MOSA, Over voltage, total leakage current, resistive leakage current, third harmonic resistive leakage current, capacitive leakage current.

References:

[1] Surge Arrestors – Metal oxide surge arrestors without gaps for a.c. systems, IEC Standard 60099-4, 2014.
[2] Surge Arrestors – Selection and Application Recommendation”, IEC Standard 60099-5, 2018.
[3] Abdullah Munir, Z. Abdul Malek and Rai Naved Arshad, “Resistive component extraction of leakage current in metal oxide surge arrester: A hybrid method”. Elsevier Journal, Measurement 173 (2021) 108588.
[4] Z. Abdul Malek, Novizon Yusoff, Mohd Fairoz and Mohd Yousuf, “Filed Experience on Surge Arrester Condition monitoring – Modified Shifted Current Method”. UPEC 2010, 31st August – 3rd Sept. 2010.
[5] S. Mohammed Arshad, Asanka S. Rodrigo, “Modified phase shifting of leakage current to condition monitoring of metal oxide surge arrestors in power system.” Mortuwa Engineering Research Conference (MERC on), 978-1-5386-4417-1/18, 2018, IEEE pp 300-305. 2018.
[6] M. Khodsuz and M. Mirzaie, “Monitoring and identification of metal-oxide Surge Arrester conditions using multi-layer support vector machine.” IET Journal, Vol 15 iss 16, pp.2501-2508, 2015.
[7] M. Khodsuz, M. Mirzaie and S. Seyyedbarzegar’ “Metal oxide surge arrester condition monitoring based on analysis of leakage current component”, Elsevier Journal, Electrical Power and Energy systems 66, pp. 188-193, 2015.
[8] Syeda Sakin Haider, Hania Ahmed, Umme Aaiman, Syda Shakeel and Abdullah Munir, “Online condition monitoring of 120 kV Zinc Oxide Surge arrestors using correlation method,” MDPI, Engineering proceedings, 2023, 46,42, MDPI journal.
[9] Behnam Ranjbar, Ali Devarshi, Rahman Dashti and Hamid Reza Shaker, “A survey of diagnostic and condition monitoring of metal oxide surge arrester in power distribution network”, MDPI, Energeis, 2022, 15,8091.