Collector Strips Research Articles

Simulation Study on Surface Temperature Distribution of Collector Strip Material Under Pantograph-Catenary Arc of Urban Rail

Simulation Study on Surface Temperature Distribution of Collector Strip Material Under Pantograph-Catenary Arc of Urban Rail

Analysis of the failure of a tramcar pantograph component through combined experimental approaches

Tramcar vehicles collect the required electrical power from the overhead contact line by means of a pantograph that carries a pan head with collector strips in sliding contact with the contact wire. Therefore, any failure of pantograph or of its components has a direct effect on the correct tramcar operation. The paper deals with a case of unexpected failures occurred on a connection element of the articulated frame of the pantograph of tramcars, causing the interruption of the service. No evidence of impact with the overhead line was detected, only it was clear that the immediate cause was the fatigue failure of a pin of the articulated connection between the upper and the lower arms of the frame of the pantograph. To clarify the original cause of the fatigue failure, an approach combining field measurements, laboratory tests and data processing to obtain the stresses acting on the pantograph failed components under service condition was adopted. It was found that the pantograph was subjected to high level of vibrations coming from the vehicle carbody, mainly due to the track irregularity. A comparative failure analysis was carried out and a solution to upgrade the component subjected to failure was proposed and implemented.

Analysis of the pantograph’s mass distribution affecting the contact quality in high-speed railway

ABSTRACT The pantograph–catenary system is an essential device, transmitting electric energy to high-speed trains. The sliding contact quality between the collector strip and the contact wire must be strictly required, keeping the good current collection quality. In this work, the displacements of two independent tension wires are described by the Fourier sine-series expansions separately. The Lagrange equation of the second kind is used to establish the dynamic equation of the catenary, which is solved by the central difference method. A multi-rigid body dynamics theory based on the relative coordinates is adopted, describing the dynamic behaviour of the pantograph. Three types of mass distribution strategies applied to the main structure of the pantograph are discussed. The mass distribution of the main structure has a large effect on the pantograph–catenary interaction, and the maximum reduction ratio of the standard deviation (STD) of the dynamic contact force reaches −35.62%, which is significant for the pantograph’s structural optimization in high-speed railways.

ОПРЕДЕЛЕНИЕ СОСТОЯНИЯ ТОКОСЪЕМНЫХ ВСТАВОК ТОКОПРИЕМНИКОВ С ПОМОЩЬЮ АКСЕЛЕРОМЕТРА

The work describes a method for determining the current collector strips of pantograph electric locomotive current collectors using an accelerometer to increase the reliability of current collectors and reduce the time for their operation. In view of the large number of failures that occur during the operation of pantographs, there is an urgent need to determine the state of the contact strips. The presented diagnostic system will allow for assessing the wear of the contact strips. The article provides diagnostic parameters for determining the state of current collector strips, as well as a method for determining the types of wear of current collector strips for various values of diagnostic parameters. The method for determining the state of collector strips is based on the vibration movements of the collector strips. During the operation of the current collector, wear of the collector strips occurs, which leads to a decrease in the mass of the collector strips. The vibrational acceleration of the collector strips changes according to the mass change, The change in vibrational acceleration is estimated using an accelerometer. Accelerometers can be easily mounted on the pantograph, and they will not affect the operation of the pantographs due to their small size and weight. The reliability of scientific statements and results is justified theoretically and confirmed by experimental studies. All theoretical and experimental studies were carried out in laboratory conditions.

On the use of experimental modal analysis for system identification of a railway pantograph

ABSTRACT This study investigates the use of experimental modal analysis to identify the modal properties of a railway pantograph system, including component behaviour within the system, for an extended frequency range in three main directions. A pantograph was mounted in a laboratory with multiple accelerometers attached and excited at the collector strip by an actuator with a sine sweep method ranging between 0 and 200 Hz. A major portion of the numerical investigations into pantograph-catenary interactions have a frequency focus below 20 Hz. The results show that this method is well suited for system identification of the pantograph, highlighting the wide range of system and component frequencies to be considered when building a numeric model. The test results for the particular pantograph used in the experiment revealed important frequencies higher than the 20 Hz limit, at 22 Hz, 39 Hz and 62 Hz.

Automatic Wear Measurement of Pantograph Slider Based on Multiview Analysis

Pantograph slider is a critical component of the electrical equipment to obtain power sources for the electric locomotive, whereas the interaction between the slider and the overhead contact line can cause persistent surface wear of the collector strip. The condition monitoring for the level of abrasion of the pantograph slider is significant to avoid major damage. In this article, an innovative approach based on multiview analysis is proposed for monitoring the surface wear of the slider in a running train, accurately measuring the residual thickness of the slider, and locating the wear defects appearing. Especially, the 3-D reconstruction technology is used for detecting the wear quantity between the upper and lower edges of the slider. First, the target edges of the slider are determined using the proposed subpixel edge detection algorithm. Second, mutual matching of the edge points between the multiview images is finished using the epipolar geometric constraint. Moreover, the 3-D reconstructions of the matching points are computed with the principle of triangulation. Finally, the wear volume of the slider can be determined. Experimental results show that the proposed method can successfully measure the abrasion of the pantograph slider under complex conditions, which demonstrate the applicability, effectiveness, and good performance of the proposed approach.

IMPROVEMENT OF METHODS AND TOOLS FOR OVERHEAD CONTACT LINES DIAGNOSTICS

This paper describes developments of tools and methods in a wear of contact wire aspect, based on optical diagnostic systems and computer vision. In general, such diagnostic systems contribute towards improved service quality, reduced costs and increased security in railways. The contact wire is an important part of the OCL. It interacts with the pantographs which are mounted on the roof of trains and moving at various speeds. It is subject to abrasion, friction, scraping, corrosion, erosion, vibration, arcing and welding at different degrees of severity depending on the wire and collector strip materials, modes of interaction and the environmental conditions that defines the wear of contact wires. Measuring systems which automatically detect the degree of wire wear are necessary in order to carry out efficient OCL infrastructure management and condition-based maintenance of contact wire. The problem of wear measurement characterized by some important determining factors like lighting conditions, background scenery and the disparity of reflexives properties of the contact wire. Besides, in order to conduct an efficient inspection, the measures have to be carried out in a changing speed of inspection train. Finally, an important issues for designing and developing measurement systems are the number of wire in measurement range. Systems have to be able to measure not less than four contact wires which are simultaneously in a range of vision and the contact wire geometric parameters such as height and displacement (stagger). The measuring systems have to acquire, process and store a considerable amount of data in real time. Due to the amount of information to be processed, a high-performance architecture and effective algorithms are needed for real-time monitoring. The hardware and software modernization of a high-speed laser system for a contact wire parameters measurements are examined. Such modernization is fulfilled mostly by implementing a real-time high-speed compression algorithms and using LED backlighting. The results of the measurement of the contact wire’s wear obtained by a modernized high-speed laser system during an inspection trips on a new modern laboratory-car are given in this article. Keywords:, optical diagnostic systems, LED emitter,overhead contact lines of railways

A Deep Learning Based Method for Detecting of Wear on the Current Collector Strips’ Surfaces of the Pantograph in Railways

In pantographs, current collector strips transmit the electrical energy they receive from the catenary to the locomotive and provide the necessary power for the locomotive's movement. In order for the current collector strips to transmit electricity to the locomotive in a healthy way, their surface must be smooth. Wear on the surface of the current collector strips reduces conductivity and can create arcs, endangering the health and safety of the pantograph and catenary system. In this paper, a Convolutional Neural Network (CNN) architecture is developed to detect wear on the current collector strips. Images obtained from pantographs used on railways were created with a clean and improved data set using Hough Transform and Power Law Transform. The created dataset contains 909 pantograph images. This dataset was trained and tested with both the developed CNN architecture and classic deep learning architectures (ResNet50, VGG16). The experimental results show that the developed CNN architecture's training results and test results are more successful than classical architectures.

Variation in predicting pantograph–catenary interaction contact forces, numerical simulations and field measurements

ABSTRACTThe contact force between the pantograph and the contact wire ensures energy transfer between the two. Too small of a force leads to arching and unstable energy transfer, while too large of a force leads to unnecessary wear on both parts. Thus, obtaining the correct contact force is important for both field measurements and estimates using numerical analysis. The field contact force time series is derived from measurements performed by a self-propelled diagnostic vehicle containing overhead line recording equipment. The measurements are not sampled at the actual contact surface of the interaction but by force transducers beneath the collector strips. Methods exist for obtaining more realistic measurements by adding inertia and aerodynamic effects to the measurements. The variation in predicting the pantograph–catenary interaction contact force is studied in this paper by evaluating the effect of the force sampling location and the effects of signal processing such as filtering. A numerical model validated by field measurements is used to study these effects. First, this paper shows that the numerical model can reproduce a train passage with high accuracy. Second, this study introduces three different options for contact force predictions from numerical simulations. Third, this paper demonstrates that the standard deviation and the maximum and minimum values of the contact force are sensitive to a low-pass filter. For a specific case, an 80 Hz cut-off frequency is compared to a 20 Hz cut-off frequency, as required by EN 50317:2012; the results show an 11% increase in standard deviation, a 36% increase in the maximum value and a 19% decrease in the minimum value.

Fibre optic sensing system for monitoring of current collectors and overhead contact lines of railways

Abstract. Fibre optic sensors are excellent tools to use for monitoring high-voltage current collectors. Because of their small cross section and electrical neutrality, they are easily integrated into the current collector strip and are well specialized for detection of high-speed load events. The conventional contact force measurement with four force sensors below the collector strips can also be simplified by using fibre optic force and acceleration sensors.

Adoption of different pantographs’ preloads to improve multiple collection and speed up existing lines

The current collection using more than one pantograph is needed in railway operation to provide power to non-electrically connected traction units and, in some cases, to reduce current density on the collector strips that heavily influences the wear on the contacting bodies. The multiple current collection may become a critical condition due to the mechanical disturbances produced on the trailing pantographs by the interaction between the first pantograph and the catenary. The present-day evolution of pantograph preload regulating systems, exploiting pressure-controlled servo-valves driven by electronic units, allows a diversification of the preloads of front and rear pantographs. In this work, a suitable solution to improve multiple pantograph collection quality is analysed by the use of a lower mean force on the leading pantograph aimed at reducing the oscillations of contact wire the trailing pantograph is subjected to. This would improve the current collection quality of the trailing pantograph, and could be pursued even admitting a slight worsening of front pantograph's performances.

Analysis of electrical interferences related to the current collection quality in pantograph–catenary interaction

The dynamic interaction between a pantograph and a catenary influences the quality of the current collection; in particular, when two pantographs are used to collect current, the second pantograph is subjected to the disturbances originated on the overhead line by the transit of the first pantograph, generally causing a deterioration of current collection quality. Under these conditions, the occurrence of continuous sparking, contact loss, and arcing cause an increase of wear for both contact wire and collector strips, but also cause variations of contact voltage and feed current that in turn produce interferences on the on-board electrical systems like drive motors and signalling system. In order to investigate the latter, a procedure for the correlation of the quality of current collection with the level of electrical interference is proposed in this article. The procedure is based on experimental and numerical models combining relationships obtained by means of laboratory tests with simulation tools. An application to a real case of double pantograph collection is presented.

A procedure for the wear prediction of collector strip and contact wire in pantograph–catenary system

The effects of friction and electrical phenomena like arcing and sparking govern the wear rate in the sliding contact between the contact wire and the collector strip, these two effects are mutually interconnected in a complex manner. A means of investigating the wear of the collector strip and the contact wire is to carry out laboratory tests that allow to perform comparative tests between different material combinations and to establish the dependence on the main parameters such as sliding speed, contact force and current intensity. A problem to be considered in the application of the laboratory test results is their extrapolation to the real operating conditions, in order to assess the effective benefit among different solutions. In this paper, a procedure that combines a wear model for the contact between collector strip and contact wire with the simulation of the dynamic interaction between pantograph and catenary is proposed. The adopted wear model is based on the wear map concept, including the effect of electrical current flow, and it is tuned by means of the results obtained on laboratory test rig. The dependence of the electrical contact resistance on the contact force between each contact strip of the pantograph and the contact wire of the overhead line is considered and the corresponding electrical current on each of the two collectors of the pantograph is evaluated. Instantaneous values of contact forces and electrical current are then fed into the wear model and the amount of the wear of the collector strips and of the contact wire along the overhead line is calculated, generating an irregular profile of the contact wire. The proposed procedure is applied to two cases: in the first one the wear of the contact wire using copper collector strips and graphite collector strips for dc line are compared. In the second one, the consequence of the variation of the mechanical tension of the contact wire on the wear levels is predicted.

Wear of pantograph collector strips

The overhead conductor system (OCS) could be one of the most economical and feasible engineering solutions to the problem of how to transmit electrical energy to intercity trains (typically at 25 kV AC) or urban/suburban trains (typically at 1.5 kV DC) along open or tunnel routes. However, the consumption of contact wire and collector strips due to wear and tear could impose a severe cost on the railway operator should the interaction between the wear couple formed by the OCS and the pantograph be poor. Following the completion of several OCS improvement projects, this paper examines the factors that might have led to higher than expected consumption of collector strips by analysing statistical data from an operational railway. The observations so far are that irregular contact wire height relative to the rails and high ambient humidity have been identified as two of the many factors that led to the abnormal consumption of collector strips.

Effect of metallised carbon content of collector strip on the wear of contact wire–collector strip pair in railway systems

AbstractAmong the topics related to the interaction between the contact wire of the overhead line and the collector strip, the wear that takes place at the contact interface, depending on both electrical and mechanical quantities, represents an important aspect of maintenance costs, affecting the mean lifetime of collectors, in terms of travelled kilometers (in terms of tenth of thousands), and contact line duration, in terms of years (between 15 and 40). Due to its importance in the global maintenance of both rolling stock and infrastructure, this topic deserved the attention of several regulations in the last decade.In order to investigate the effects of electro‐mechanical wear on both contact wire and contact strip, a new test equipment has been designed and installed at Politecnico di Milano. A series of tests have been performed, involving different kinds of collector strip materials and contact conditions, tested at varying speeds and current intensities.This investigation concerned different collector strip configurations intended for 3kV D.C. lines. The combination of different contents of copper and metallised carbon in the collector has been found to influence the wear rate of both collector strip and contact wire. Differences in wear up to four times for the former and up to six times for the latter have been found depending on the composition of the collector. Copyright © 2006 John Wiley & Sons, Ltd.

FEM OF STRAIN AND THERMAL LOAD OF A TRAIN CURRENT COLLECTOR WITH CONTACT FORCE DURING INTERACTION WITH CATENARY

This paper reports on FEM modeling results simulating the effect of current on the collector strips thermal and strain characteristics during the interaction between pantograph and the overhead contact line.

Hardware in the Loop Test‐Rig for Identification and Control Application on High Speed Pantographs

Trains current collection for traction motors is obtained by means of a sliding contact between the overhead line (OHL) and the collector strips mounted on the pantograph head. The normal force by which the collector presses against the contact wire ensures the contact pressure for the electrical contact. As the train speed increases, the variation of contact force between pantograph and catenary increases, and the pantograph‐OHL dynamic interaction becomes greater. This condition causes excessive mechanical wear and contact wire uplift (for high values of contact forces), and leads to high percentage of contact loss, arcing and electrically related wear.The topic of actively controlled pantograph is gaining more interest as a tool to increase the performance of the current collection at high speed. In the last few years, it appears possible to transfer the knowledge based on numerical experiments, to the real operating condition. An important step in this direction is the set up of a laboratory hardware in the loop test‐rig in which the control strategies and the actuation can be tested, before tests performing in real life conditions, in order to demonstrate their actual feasibility. The present paper describes an hardware in the loop (HIL) test‐rig developed by the authors, which allows to reproduce the dynamical interaction between overhead lines and pantograph in high speed railways. Using the described laboratory set‐up, experimental investigation on the problems related with pantograph‐OHL interaction can be performed, very similarly to the real life operating conditions, with the advantage of varying test parameters and conditions easily.

A two-dimensional position sensitive gas chamber with scanned charge transfer readout

We have constructed and tested a two-dimensional position sensitive parallel-plate gas ionization chamber with scanned charge transfer readout. The scan readout method described here is based on the development of a new position-dependent charge transfer technique. It has been implemented by using gate strips perpendicularly oriented to the collector strips. This solution reduces considerably the number of electronic readout channels needed to cover large detector areas. The use of a 25 μm thick kapton etched circuit allows high charge transfer efficiency with a low gating voltage, consequently needing a very simple commutating circuit. The present prototype covers 8×8 cm 2 with a pixel size of 1.27×1.27 mm 2 . Depending on the intended use and beam characteristics a smaller effective pixel is feasible and larger active areas are possible. This detector can be used for X-ray or other continuous beam intensity profile monitoring.

Phototube sensor for monitoring the quality of current collection on overhead electrified railways

A new measurement system able to detect the occurrence of arcing between the pantograph and the overhead contact line was studied and set up. The system uses photomultiplier tubes to measure the duration of the ultraviolet emission due to electric arcing. The major advantages of the system proposed are its non-invasivity with respect to the pantograph equipment, its reliability and its low cost. Correlation with data acquired during high-speed test runs from different sensors (e.g. currents measured in an equipotential wire between the front and the rear pantographs, images acquired from a TV camera), provided the opportunity to perform an efficient calibration and an analysis of selectivity of the phototube sensor. Data from the phototube sensor along with various other information lead to the definition of a reliable index for evaluating the quality of the current collection. The determination of such an index has primary relevance for maintenance activities, for computing the minimal thrusts to be applied to the pantograph at different speeds and for testing new materials for overhead contact wires and collector strips.

Metallic impurities in the ASDEX scrape-off layer

An experimental investigation of metallic impurities has been made in the ASDEX divertor in order to better understand their likely sources and production mechanisms. The impurities were collected on rotatable carbon collector strips which were exposed to the scrape-off layer plasma near the upper outer divertor plate under various discharge conditions. Quantitative ion beam analysis of exposed samples was subsequently carried out by Rutherford backscattering spectroscopy, proton induced X-ray emission and nuclear reaction spectroscopy. Time resolved measurements and spatial profiles of collected impurity fluxes reveal an increase in collected metallic impurities during auxiliary neutral beam heating of plasma discharges causing strong erosion of the copper divertor plate. To a rough approximation, 0.2% of this auxiliary heating power is invested in the production of stainless steel impurities. Measurements made for single-null divertor discharges show a copper flux of 6 × 1017 atoms·s−1 in the scrape-off layer which is not directly sputtered from the target plates. Collected impurity fluxes in the divertor chamber are found to increase with both the main plasma current and the density. Measurements made after boronization reveal an initial reduction in collected stainless steel impurities although boronization does not have any long term effect on the suppression of such impurities. Some limitations of the collector probe technique are also pointed out, and planned improvements of the existing setup are outlined.