International Review on Modelling and Simulations (I.RE.MO.S.), Vol. 10, N. 3 ISSN 1974-9821 June 2017 Copyright © 2017 Praise Worthy Prize S.r.l. - All rights reserved https://doi.org/10.15866/iremos.v10i3.11482 160 160 160 Analysis of Flashover Induced by Transient Current During Multiple Lightning Strokes on a Train Kelvin M. Minja, Pius V. Chombo, Narupon Promvichai, Boonruang Marungsri Abstract – Power system outage due to the occurrence of flashover (across insulators) when lightning induced voltages exceed insulators’ voltage withstand capabilities have been a major investigation in recent studies. Since the Overhead catenary system uses overhead power lines which are exposed to lightning incidences, the concerns have been made in protection against lightning strikes. The knowledge of lightning and its most influential parameters are of great importance in the safe and reliable operation of the Overhead catenary system. In this work, analysis of flashover when lightning strikes on train’s pantograph at the mast and between two masts were studied. Furthermore, the effects of the magnitude, waveforms, polarity, multiplicity and grounding resistance were investigated. In this task, the impact of lightning parameters has been achieved with computer simulation tool (ATPDraw). It was shown that the negative multiple lightning of magnitude - 34 kA and above leads flashover when strikes on pantograph at the mast and between two masts. However, the grounding resistance was recognized to have higher predominance in mast induced voltages when a lightning strike occurs at the mid-span unlike along the mast. Hence, the lightning protection design should consider the multiplicity of negative lightning strokes outcome from the point of hitting. Copyright © 2017 Praise Worthy Prize S.r.l. - All rights reserved. Keywords: Catenary, Multiple Lightning Strokes, Flashover, Grounding Resistance, ATP Draw Nomenclature Ax Auxiliary line Rt Return line Ct Catenary line X 1 S-Rail X 2 I-Rail X 3 Catenary line with composite insulator X 4 Return line with spool insulator X 5 Auxiliary line with pin insulator R 1 Radius between mast and auxiliary line R 2 Radius between mast and return line R 3 Radius between mast and catenary line H Height of the mast L 1 Vertical distance between auxiliary and return line L 2 Vertical distance between return and catenary line L 3 Distance between catenary line and ground Z aux Impedance of the auxiliary line Z return Impedance of the return line Z catenary Impedance of the catenary line R f Mast grounding resistance IU International unit I. Introduction Until now, catenary contact system has become more useful for feeding traction power to electric vehicle [1]- [6]. In spite of modernization in the electrified railway system, lightning has been a crucial problem in the overhead catenary system [1]-[2]. Statistically, most of the power system outage caused by transient current characteristics are due to lightning strokes [1], [7]-[9]. A power system failure of the overhead catenary system is triggered by direct lightning strokes to phase conductor, shielding wire and ground in line proximity [1], [10]. However, lightning strokes on phase conductor influence dynamic overvoltages, which can disturb the stability of system to a great extent [9]-[11]. It has been reported that when induced overvoltage overreach insulation withstands capability, lightning flashover across insulators occurs [2]. Many works have been performed to estimate the lightning strokes consequences in the overhead catenary system [1], [3]-[4], [12]-[17]. Catenary contact system is among of elevated railway system that has been affected by lightning incidences in Bangkok, Thailand. It has been reported in [18] lightning magnitude ranges 11-171 kA with a positive polarity which accounts for 5% and -10 to -139 kA with negative polarity is 95% of all flash activities. In addition, [19]- [22] described that negative lightning could associate with multiple strokes per flash. Ref. [19], [21]-[22] showed the reported multiple strokes averaging 3 to 4 strokes per flash with intervals of tens of milliseconds. In recent studies, lightning end results were analyzed when it strikes on the mast, conductors, and traction substation of the overhead catenary system by using different