Vol 87, No 2 (2016)

Analysis of the causes of failure showed that failures of a commutator and brush assembly (CBA) of electric machines make up 10–15% of the total number of failures. Many different methods to control the degree of sparkling of the CBA plates based on the measurement of different physical values and connected with the CBA sparkling processes were developed. The article describes a method of automated analysis of the degree of sparkling of certain commutator electric machine with the use of stroboscopic photo recording of sparkling and computer processing of the photo images of the sparkling plates aiming at obtaining the degree of sparkling for each collector plate. Processing methods of such images using the original OpenCV software library including image identification, classification and obtaining of the integral image and its analysis were considered. The proposed method allows the degree of sparkling under the trailing edge of the brush for each commutator plate to be determined. Determination is carried out for a large number of switching cycles for each brush, which allows statistical error to be avoided; in addition, automation of measurements decreases the influence of human factor on the test result.

A contact system is a nonredundant technical structure of electric railways that should provide uninterrupted power supply for railway vehicles. The failure of one part can lead to failure of the contact system. About 20% of damage to contact systems is due to inadmissibly high temperature at part of an overheated catenary. In this paper, normative indices are analyzed to determine the state of the terminal under operating conditions. The existing methods of thermal control are unable to determine the current heat state of an electric bolted connection with required accuracy. Heating control of electrical connections is suggested. To determine the state of the electrical connection, the factor of defectiveness due to heating is selected. As a result, criteria for determining the state of an electrical connection are obtained, which allows a methodology to be developed for monitoring the quality of an electrical connection.

A method for improving the power factor of an ac locomotive with the commutator motor operating in the regenerative braking mode is proposed. The method improves the control system algorithm of the power converter. The new switching method of inverter thyristors regulates the curve of the instantaneous power during the main switching. It allows reducing the period in which the energy flow passes to the locomotive, leading an increase in the average value of the instantaneous power. A “traction substation–electric traction network–locomotive in the regenerative braking mode” mathematical model is presented to verify efficiency of the method. The model consists of several interacting electric power substations, a section of electric traction grid, a locomotive power transformer, a four-zone inverter, a control system of reversible converter, and a dc circuit. The model is realized in the OrCAD software.

Failures of reversible converters (RCs) in ac electric locomotives can cause failures of ac locomotive power equipment. Depending on their severity, the electric locomotive can be placed in one of several different modes, from partial loss of function to complete halting. With this in mind, it becomes important to develop (upgrade) diagnostic support of RCs and decide on a procedure of diagnostics that would make it possible to identify defects of RCs not only in the running mode, but also in the stationary mode, during scheduled and unscheduled repairs of an electric locomotive. To provide a more reliable evaluation of the technical condition of the RC functional control, is necessary to check the connections between the converter parts. It is also important that the diagnostics allows modifications of input signals supplied to the converter inlet, depending on the results of a scheduled check for specifying the diagnosis and troubleshooting. The stationary automated diagnostics system makes it possible to determine the technical condition of an RC in the rectifier mode in stationary conditions and is intended for use in testing an RC exposed to simulated operational effects. In the current phase of development, the diagnostics system allows evaluation of the capacity and correctness of implementing the RC control algorithm in all four adjustment zones, as well as identification of RC leg interruptions. Together with the algorithm for RC diagnostics, the suggested method makes it possible to conduct functional tests and identify a particular defect, as well as check the operation of the RC by monitoring the work of the converter as a single diagnosed object before the RC is installed on the locomotive. This will ensure faster and more reliable diagnostics and make it possible to almost completely avoid the use of RCs with unidentified defects.

Theoretical backgrounds of magnetic field flow inside stable objects, for example, inside a cylindrical surface, are considered. A cylindrical surface is used in the form of dielectric bushing. Three (or a multiple of three) coils are placed outside the bushing, and a three-phase voltage is supplied via crystal diodes to the coils. Coils generate a magnetic field sequentially inside the bushing with shifts in space and time. The magnetic field is coupled with a ferromagnetic body of a certain size placed inside the bushing and moves it. The proposed ferromagnetic mass flow technique inside a cylindrical surface may be used for shot peening of a part’s surface after removal of the shot damping effect at the final stage of the flow. The proposed model of the magnetic engine may be in demand in the case of a low rotational speed of mechanisms or working machines.

Auxiliary machines of electric trains provide the operation of traction motors and electrical and pneumatic equipment. The main condition of safe operation of the asynchronous electric drive of auxiliary machines is the maintenance of the operation mode of the electric drive in terms of the basic technical data, according to which NVA-55 electric drives are matched by nominal operation (long-term) mode S1. The effect of supply voltage on the operation of locomotive auxiliary machines is considered. Auxiliary machines are used under poor conditions on alternating current electric trains. Disbalance of the motor currents occurs even at nominal voltage of the overhead contact system and operable phase-shifting device. In operation, the voltage on the contact wire line is not constant and the equipment modes can be inconsistent with the nominal one, which leads to a significant number of failures of auxiliary equipment. This makes it necessary for the microprocessor control system to use the controlled auxiliary electric drive. An individual autonomous inverter with fully balanced sinusoidal output voltage allows one to increase the reliability of the induction motor drive, while the proportional control of the blower motor reduces the power consumption.

Upgrading the traction power supply is an important task in developing railway power engineering. The Russian railway transport development strategy envisions updating power supply equipment, including the reconstruction of 763 traction substations, which will be very expensive. Power transformers are the main, and most expensive, apparatuses in traction substations. They account for more than 50% of the cost of substation equipment. Steps in increasing the operating life of power traction substations during upgrading the ac traction substations are described in the present article. Substation upgrading involves up-to-date equipment and technologies. The decision to replace or further use existing substation power transformers is primarily based on data on the real condition of transformers. The 25 kV alternating current power transformers traction substations operate with the high unbalanced current of windings. The current of the most loaded winding can possess double magnitude of currents in other windings, while the losses of windings differ by four times. A qualitative analysis of transformer operating life based on insulation wear for three traction substations is presented. The winding with maximum insulation wear is assessed on the basis of power consumption. In order to extend the operating life, windings need to be connected to neutral links of a traction substation.

Issues of using an automated monitoring system for implementation of the principles of lean production in the traction power supply system of Russian railways are considered. As a result of analysis of the operational efficiency of existing systems of monitoring of railway infrastructure facilities from the point of view of the principles of lean production, unused capabilities of the monitoring systems were revealed. It is suggested to take advantage of these unused capabilities independently or in combination with other components. The efficiency of application of the suggested solutions is proven due to reduction of time for repair work, an increase in overhaul periods, an increase of reliability of the traction power supply system, and making the work time more effective of the maintenance personnel. The necessity of combining the principles of lean production is justified not only with the information monitoring systems, but with other modern management approaches and practices. Use of lean production technologies will permit reduction in the time for repair works, an increase in the overhaul periods, an increase in the reliability of the traction power supply systems, an increase in the efficiency of the work time of maintenance personnel. It can be expected that it will lead to a significant decrease in the range of repair work (will exclude the repair of units without defects) and an increase in the overhaul period. As a result, lean production will permit using smoothly not only the information monitoring system, but also other modern management approaches and practices.

One promising method of increasing the power efficiency of an electrified railway is reducing the power capacity of the transfer process and the consumption of the electric power to the train traction. A 25-kV ac traction power supply a system features the drastically variable one-phase train load, which leads to a change in voltage on substations buses and train current collectors, as well as an increase in loss powers. The rules of the composition of the traction power supply for the fulfillment of the train schedule normalize the voltage on the substation buses and train current collector of no more than 29 kV and no less than 21 kV. Analysis of operation of the traction power supply system is carried out, and steps are taken to increase the engineering and economic performance of 25-kV ac railways. A new notion of normal power supply circuits of traction loads synthesized on the basis of simulation is presented. Analyzing the structure of the imbalance of electric power and voltage in traction network allows one to define steps toward increasing power efficiency. The accuracy of the initial data is determined by comparing the expected and real train schedules, as well as electric load curves. The simulation accuracy is determined on the basis of predictable power and voltage losses with monitoring results.