Damages of the Section Insulator Guide Caused by Electric Arc

Scientific Journal of Silesian University of Technology. Series Transport, 2021

This article presents the results of a research on the operational damage to sectional insulator guides made of hard electrolytic copper Cu-ETP (Electrolytic Tough Pitch Copper). The guides were used on various rail routes, in real conditions, on which the trains ran at maximum speeds between 40 and 120 km/h for periods of 6 or 12 months. The microstructure of the surface, the working layer of the guide, which contacts the graphite plate of the current collector and the cross-section of the guide in the place where it was damaged was examined using the Olympus light microscope. The analysis of the chemical composition in the EDS micro-regions was performed using the Zeiss Supra 53 scanning electron microscope (SEM), while the qualitative X-ray phase analysis was performed with the use of the Panalytical X'Pert diffractometer. Scratches and deformations of the surface layer characteristic of the phenomenon of friction caused by the current collector were observed in the microstructure of the damaged parts of the guides of section insulators. The effect of a very intense oxidation process was also observed, as well as the effects of an electric arc, which according to the author, is the factor that has the most destructive effect on the condition of the guides.

Challenges for the market of production, operation and maintenance of rail vehicles, 2021

In order to allow a smooth passage of the pantograph slide under the insulating part of the section insulator, guides are used, which are usually made of hard electrolytic copper with the symbol Cu-ETP. The guides stabilize the pantograph head during slipping and protect against slipping on the insulator structure. The article presents the results of tests on the section insulator guides made of copper Cu-ETP, which were operated on various railway routes, in real conditions, with maximum train speed from 40 km/h to 120 km/h for a period of 6 or 12 months. The microstructure of the surface layer, the working guide, which contacts with the graphite plate of the current collector, was performed using the Zeiss Supra 53 scanning electron microscope, as well as the analysis of the chemical composition in EDS micro-areas. In the microstructure of the final part of the section insulators guides operated in various conditions, scratches and distortions of the surface layer produced by the current collector-glider were observed. In addition, features resulting from a very intensive oxidation process were also observed during the short-term flow of equalizing currents initiating ignition of the electric arc. Although it is extinguished by the insulator's cones, it can be assumed that the resulting craters are the effect of an electric arc that led to the local burning of the material of the native section insulator.

rchives of Materials Science and Engineering, 2024

The paper presents the results of the stereometry specification of the damaged guide of a section insulator of railway electric traction made of hard electrolytic copper Cu-ETP. The tested guides were withdrawn from service due to damage. Design/methodology/approach: The tests were carried out on guides that were operated for 6 or 12 months on lines where trains moved at a maximum speed of 40 or 120 km/h.The analysis of the geometry of the surface was based on data acquired by measuring selected fragments of guides and executing them on a laser profile measurement gauge MicroProf of the FRT company. The microstructure analysis was performed on the ZEISS SUPRA 25 Scanning Electron Microscope (SEM) using the EDS. Findings: Analysis of the test results showed that the electric arc is the most destructive phenomenon that accompanies the operation of the guides of section insulators made of Cu-ETP copper. The stereometric tests have characterised the guide surfaces using specific values, e.g., copper drop height or abrasion depth. Research limitations/implications: Since the tests were carried out on guides operated on the railway electrical traction, in real conditions, it is very difficult to acquire data on operating parameters such as voltage and electric current, the pressure force of the pantograph on the electric traction, the temperature to which the guide heats up as a result of an electric discharge or under the influence of flowing air, high current, etc. Practical implications: The most important mechanisms destroying the guide made of Cu-ETP copper have been characterised, and thanks to this, in the next stage of research, it will be possible to counteract the effects of damage effectively. Originality/value: The presented test results concern guides operated in real conditions and show the effects of the electric arc and the accompanying physical phenomena. The test results are not the result of laboratory simulations intended to reflect real operating conditions.

IEEE Transactions on Power Delivery, 2009

Pantograph arcing with ac supply generates transients, cause asymmetries and distortion in supply voltage and current waveforms and can damage the pantograph and the overhead contact line. The asymmetry generates a net dc component and harmonics, which propagate within the traction power and signalling system and causes electromagnetic interference. Unlike dc-fed systems (Part I), the arcing in ac supply is complex because of the zero crossing of currents and voltages. In this paper, we discuss the mechanisms of sliding contact and arcing between pantograph-contact wire using the experimental setup described in Part I. Influences of various parameters and test conditions on arcing phenomenon and their signature patterns on the supply voltage and current waveforms are presented. It is shown how the arcing mechanism and corresponding asymmetry in the voltage and current waveforms are governed by line speed, current, supply voltage, inductive load, and pantograph material. The asymmetry in the current waveform is mainly due to the difference in the duration of successive zero-current regions and uneven distortion of the waveshapes. This, in turn, creates the asymmetry in the voltage waveform. The findings presented in this paper could be beneficial for coming up with appropriate mitigation techniques from the electromagnetic interference due to pantograph arcing in ac traction systems.

IEEE Transactions on Power Delivery, 2009

Pantograph arcing is a common phenomenon in electrified railway systems. This is also a source of broadband-conducted and radiated electromagnetic interference (EMI) for vehicle as well as traction power and signaling systems. In this paper and the companion paper, experimental analyses of pantograph arcing phenomena are presented for dc and ac feeding systems, respectively. Influences of different parameters on dc traction system, such as supply-voltage polarity, relative motion between pantograph and overhead contact wire, namely, forward motion along the track (longitudinal), and lateral sliding motion of the pantograph (zigzag) are presented here. From the voltage and current waveforms of the test runs, it is shown that pantograph arcing is a polarity-dependent phenomenon. For the positive-fed overhead traction system, where pantograph is cathode, the supply interruptions due to zigzag motion are comparatively less compared to negatively fed traction systems. As a result, the transients, due to pantograph arcing, are more frequent in negatively fed traction systems. It is found that the arc root movement along the electrode surfaces (pantograph-contact wire) is governed by the relative motion and polarity of the electrodes. The analyses presented in this paper also form a foundation to understand the pantograph arcing process and the corresponding influential parameters with the ac supply presented in the companion paper. The findings presented in this paper could be beneficial for coming up with appropriate mitigation techniques from the EMI due to pantograph arcing in dc-fed traction systems.

Materials

This paper presents the results of research on a newly developed surface layer made by laser remelting the working surface of the Cu-ETP (CW004A, Electrolytic Tough Pitch) copper section insulator guide with Cr-Al powder. For the investigation, a fibre laser was used with relatively high power, reaching 4 kW, so as to ensure a high gradient of cooling rate for microstructure refinement. The microstructure of the transverse fracture of the layer (SEM) and the distribution of elements in the microareas (EDS) were investigated. The test results showed that chromium does not dissolve in the Cu matrix, and its precipitates take the shape of dendrites. The hardness and thickness of the surface layers as well as the friction coefficient and the influence of the Cr-Al powder feeding speed on them were examined. For the distance from the surface to 0.45 mm, the hardness of the produced coatings is above 100 HV0.3, while the friction coefficient of the produced coatings is in the range of 0.6...

IEEE Transactions on Power Delivery, 2009

Pantograph arcing is a common phenomenon in electrified railway systems. This is also a source of broadband-conducted and radiated electromagnetic interference (EMI) for vehicle as well as traction power and signaling systems. In this paper and the companion paper, experimental analyses of pantograph arcing phenomena are presented for dc and ac feeding systems, respectively. Influences of different parameters on dc traction system, such as supply-voltage polarity, relative motion between pantograph and overhead contact wire, namely, forward motion along the track (longitudinal), and lateral sliding motion of the pantograph (zigzag) are presented here. From the voltage and current waveforms of the test runs, it is shown that pantograph arcing is a polarity-dependent phenomenon. For the positive-fed overhead traction system, where pantograph is cathode, the supply interruptions due to zigzag motion are comparatively less compared to negatively fed traction systems. As a result, the transients, due to pantograph arcing, are more frequent in negatively fed traction systems. It is found that the arc root movement along the electrode surfaces (pantograph-contact wire) is governed by the relative motion and polarity of the electrodes. The analyses presented in this paper also form a foundation to understand the pantograph arcing process and the corresponding influential parameters with the ac supply presented in the companion paper. The findings presented in this paper could be beneficial for coming up with appropriate mitigation techniques from the EMI due to pantograph arcing in dc-fed traction systems.

IEEE Intl. Symposium EMC 2008, Detroit, Michigan, USA, 2008

The most common and yet unavoidable EMC problems with electrified railways are due to pantograph arcing. This distorts the waveform of the supply voltage and current, can generates transients during the zero crossings of the current and can cause interference with the traction power and signalling system. Pantograph arcing is a complex phenomenon and depends on speed of the train, current, presence of inductance etc. In a sliding contact like pantograph and contact wire, the arc root moves across both electrodes because of the relative motion between them. In this paper, we will present an experimental analyses of the arc root movement and influence of different parameters on it using a laboratory setup.

2012 IEEE Fifth Power India Conference, 2012

Traction insulators are solid core insulators widely used for railway electrification. Constant exposure to detrimental effects of vandalism, and mechanical vibrations begets certain faults like shorting of sheds or cracks in the sheds. Due to fault in one/two sheds, stress on the remaining healthy sheds increases, owing to atmospheric pollution the stress may lead to a flashover of the insulator. Presently due to non availability of the electric stress data for the insulators, simulation study is carried out to find the potential and electric field for most widely used traction insulators in the country. The results of potential and electric field stress obtained for normal and faulty imposed insulators are presented.