Investigation of an Insulator Flashunder in an 150 kV OTL of the Power System of Crete

D. Pylarinos, I. Pellas

Abstract


Overhead Transmission Lines (OTLs) are used in Power Systems to carry High Voltage between substations, usually over long distances. Faults in OTLs are bound to happen and thus locating and coping with them is an important aspect of OTL’s operation and maintenance. These faults may be of temporary or permanent nature, with certain types of faults progressing over time from the first category to the second. Local weather may also have a direct effect on the occurrence of faults resulting to puzzling events. A special category, often complex in nature, is insulator faults. Insulators are used in OTLs to support phase conductors while not allowing current to flow through the tower’s body to the ground. Traditional ceramic insulators used materials such as porcelain and glass as insulation, but in the last decades composite insulators with two insulating parts (a glass core/rod and a rubber housing), have also known great use mainly due to their low weight and their capability to withstand pollution. However, they are subjected to certain faults unique to them, such as flashunders. Flashunder is a term commonly used lately to describe faults that are related to the rod/housing interface of composite insulators. Such faults are rather difficult to locate as the electrical discharge does not create an easily visible trace (as in the case of flashovers) or a permanent mechanical fault (as in the case of brittle fractures). Such a fault occurred for the first time in the Transmission System of Crete in 2019 and this paper follows and discusses the incident and the experience gained.


Keywords


flashunder; overhead; transmission; line; insulator; power; high voltage; permanent; transient; fault

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References


H. H. Farr, Transmission line design manual, United States Departmentof the Interior, 1980

L. L. Grigsby (editor), The electric power engineering handbook: electric power generation, transmission and distribution, CRCPress - Taylor and Francis Group, 2012

K. O. Papailiou (editor), Overhead lines, CIGRE Green Books, Springer, 2017

European Network of Transmission System Operators for Electricity, Best protection practices for HV and EHV AC-transmission systems of ENTSO-E Electrical Grids, ENTSO-E, 2018

R. K. Tajput, A textbook of power system engineering, Laxmi Publications, 2006

N. Veerappan, S. R. Krishnamurthy, Power system switchgear and protection, S. Chand Publishing, 2009

CIGRE WG B2.45, Vegetation fire characteristics and the potential impacts on overhead line performance, CIGRE, 2019

H. F. Vosloo, The need for and contents of a life cycle management plan for Eskom transmission line servitudes, MSc Thesis, Rand Afrikaans University, 2004

D. Pylarinos, I. Pellas, “Incorporating open/free GIS and GPS software in power transmission line routine work: the case of Crete and Rhodes”, Engineering, Technology & Applied Science Research, Vol. 7, No. 1, pp. 1316-1322, 2017

CIGRE WG 33-04, TF 01, “A review of current knowledge: polluted insulators”, CIGRE, 1998

K. Papailiou, F. Schmuck, Silicone composite insulators: materials, design, applications, Springer, 2013

CIGRE WG B2.21, Assessment of in-service composite insulators by using diagnostic tools, CIGRE, 2013

Electric Power Research Institute, Field guide: visual inspection of polymer insulators, 2006

R. Gorur, “Reviewing modes of insulator failure”, INMR, 2011, available at: http://www.inmr.com/reviewing-modes-of-insulator-failure/

D. Pylarinos, K. Siderakis, E. Koudoumas, E. Thalassinakis, “Polymer insulators and coatings in the Cretan power system. the transmission line case”, 9th Mediterranean Conference on Power Generation, Transmission Distribution and Energy Conversion, Athens, Greece, 2-5 November, 2014

S. Gubanski, “Greek power company evaluates alternatives to combat pollution in transmission system on Crete”, INMR, Vol. 10, No. 4, 2002

INMR, “Greek utility battles pollution affecting island transmission system”, INMR, Vol. 15, No. 4, pp. 24-38, 2007

A. Sykaras, V. Rajini, M. G. Danikas, R. Sarathi, “A study of SiR/EPDM mixtures for outdoor insulators”, Engineering, Technology & Applied Science Research, Vol. 7, No. 4, pp. 1737-1740, 2017

CIGRE WG B2.21, Guide for the assessment of composite insulators in the laboratory after their removal from service, CIGRE, 2011

K. Lagouvardos, V. Kotroni, A. Bezes, I. Koletsis, T. Kopania, S. Lykoudis, N. Mazarakis, K. Papagiannaki, S. Vougioukas, “The automatic weather stations NOANN network of the National Observatory of Athens: operation and database”, Geoscience Data Journal, Vol. 4, No. 1, pp. 4-16, 2017

Database of Weather Stations of the National Observatory of Athens, available at: http://meteosearch.meteo.gr/

T. Stamatakis, “Statistical analysis of faults on 150 kV transmission lines of the power system of Crete”, Degree Thesis, Electrical Engineering Department, Technological Educational Institute of Crete, 2014 (in Greek)

N. Mavrikakis, K. Siderakis, P. N. Mikropoulos, N. Katsarakis, “Condition assessment of a field-aged 150 kV HTV SIR suspension insulator following flashover”, ISH 19th International Symposium on High Voltage Engineering, Pilsen, Czech Republic, August, 23–28, 2015




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