The dynamics of a current collection system for an electric locomotive

1971 ◽  
Vol 322 (1551) ◽  
pp. 447-468 ◽  
Keyword(s):  
Contact Force ◽  
Wave Speed ◽  
Operating Conditions ◽  
Electric Locomotive ◽  
Current Collection ◽  
Loss Of Contact ◽  
The Wire ◽  
Linear Differential ◽  
Valid Solution ◽  
A Current

The motion of an overhead trolley wire, suspended at equal intervals by stiff springs, in response to a pantograph moving with constant speed is analysed. The pantograph is modelled by two discrete masses connected by springs and dampers. Away from the supports the inertia and elasticity of the pantograph can be neglected and a simple solution for the wire and pantograph displacement is obtained. Near a support this solution is not valid as it predicts discontinuities in the vertical pantograph velocity. A different first approximation is then required in which the support elasticity and the pantograph inertia and elasticity must be included. This problem is reduced to that of solving a system of four linear differential equations containing one term with a stretched argument. The numerical and asymptotic solution of such a system is discussed and results are obtained for the contact force and pantograph displacement near a support in typical operating conditions. This disturbance at the support is propagated with the wire wave speed and reflected at the subsequent support, thus interacting with the pantograph again. This interaction is analysed and a uniformly valid solution obtained for the contact force over a complete span. Some conclusions are made about possible operating conditions in which loss of contact between the pantograph and the wire may occur.

Validation of mathematical model of electrothermal calculation of DC catenary on the basis of scale model

2018 ◽  
Vol 77 (4) ◽  
pp. 222-229 ◽  
Author(s):  
A. V. Paranin ◽  
A. B. Batrashov
Keyword(s):  
Mathematical Model ◽  
Operating Conditions ◽  
Scale Model ◽  
Contact Network ◽  
Scaled Model ◽  
Cross Sectional ◽  
Current Collection ◽  
Topological Features ◽  
Study Results ◽  
Real Physical Process

The article compares the results of calculation of the finite element simulation of current and temperature distribution in the scale model of the DC catenary with the data of laboratory tests. Researches were carried on various versions of the structural design of catenary model, reflecting the topological features of the wire connection, characteristic of the DC contact network. The proportions of the cross-sectional area of the scaled model wires are comparable to each other with the corresponding values for real DC catenary. The article deals with the operating conditions of the catenary model in the modes of transit and current collection. When studying the operation of the scale catenary model in the transit mode, the effect of the structural elements on the current distribution and heating of the wires was obtained. Within the framework of the scale model, theoretical assumptions about the current overload of the supporting cable near the middle anchoring have been confirmed. In the current collection mode, the experimental dependences of the current in the transverse wires of the scale model are obtained from the coordinate of the current collection point. Using the model it was experimentally confirmed that in the section of the contact wire with local wear, not only the temperature rise occurs but also the current redistribution due to the smaller cross section. Thus, the current share in other longitudinal wires of the scale model increases and their temperature rises. Scale and mathematical models are constructed with allowance for laboratory clamps and supporting elements that participate in the removal of heat from the investigated wires. Obtained study results of the scale model allow to draw a conclusion about the adequacy of the mathematical model and its correspondence to the real physical process. These conclusions indicate the possibility of applying mathematical model for calculating real catenary, taking into account the uneven contact wear wire and the armature of the contact network.

Effect of shape/size and distribution of microgeometries of textures on tribo-performance of crankpin bearing

2021 ◽  
pp. 135065012110105
Author(s):  
Nguyen Van Liem ◽  
Wu Zhenpeng ◽  
Jiao Renqiang
Keyword(s):  
Friction Coefficient ◽  
Friction Force ◽  
Contact Force ◽  
Distribution Density ◽  
Hydrodynamic Lubrication ◽  
Operating Conditions ◽  
Asperity Contact ◽  
Combined Model ◽  
Obvious Effect ◽  
Area Density

The effect of the shape/size and distribution of microgeometries of textures on improving the tribo-performance of crankpin bearing is proposed. Based on a combined model of the slider-crank mechanism dynamic and hydrodynamic lubrication, the distribution density, area density, and shape of spherical textures, square-cylindrical textures, wedge-shaped textures, and a hybrid between spherical texture and square-cylindrical texture on the crankpin bearing's tribo-performance are investigated under different operating conditions of the engine. The tribological characteristic of the crankpin bearing is then evaluated via the indexes of the oil film pressure p, asperity contact force, friction force, and friction coefficient of the crankpin bearing. The research results show that the distribution density with n = 12 and m = 6, and area density with α = 30% of various microtextures have an obvious effect on ameliorating the crankpin bearings tribo-performance. Concurrently, at the mixed lubrication region, the shape of the square-cylindrical texture on improving the tribo-performance is better than the other shapes of the spherical texture, wedge-shaped texture, and spherical and square-cylindrical texture. Particularly, all the average values of the asperity contact force, friction force, and friction coefficient with a square-cylindrical texture are significantly reduced by 14.6%, 19.5%, and 34.5%, respectively, in comparison without microtextures. Therefore, the microtextures of the spherical texture applied on the bearing surface can contribute to enhance the durability and decrease the friction power loss of the engine.

Experimental Investigation of High-Speed/High-Voltage SMA Actuation

2017 ◽  
Author(s):  
Paul Motzki ◽  
Tom Gorges ◽  
Thomas Würtz ◽  
Stefan Seelecke
Keyword(s):  
Shape Memory ◽  
High Voltage ◽  
Supply Voltage ◽  
High Energy ◽  
Wire Diameter ◽  
High Current ◽  
Sma Actuator ◽  
The Wire ◽  
Supply Voltages ◽  
A Current

The thermal shape memory effect describes the ability of a deformed material to return to its original shape when heated. This effect is found in shape memory alloys (SMAs) such as nickel-titanium (NiTi). SMA actuator wire is known for its high energy density and allows for the construction of compact systems. An additional advantage is the so-called “self-sensing” effect, which can be used for sensor tasks within an actuator-sensor-system. In most applications, a current is used to heat the SMA wires through joule heating. Usually a current between zero and four ampere is recommended by the SMA wire manufacturers depending on the wire diameter. Therefore, supply voltage is adjusted to the SMA wire’s electrical resistance to reach the recommended current. The focus of this work is to use supply voltages of magnitudes higher than the recommended supply voltages on SMA actuator wires. This actuation method has the advantage of being able to use industry standard voltage supplies for SMA actuators. Additionally, depending on the application, faster actuation and higher strokes can be achieved. The high voltage results in a high current in the SMA wire. To prevent the wire from being destroyed by the high current, short pulses in the micro- and millisecond range are used. As part of the presented work, a test setup has been constructed to examine the effects of the crucial parameters such as supply voltage amplitude, pulse duration, wire diameter and wire pre-tension. The monitored parameters in this setup are the wire displacement, wire current and force generated by the SMA wire. All sensors in this setup and their timing is validated through several experiments. Additionally, a highspeed optical camera system is used to record qualitative videos of the SMA wire’s behavior under there extreme conditions. This optical feedback is necessary to fully understand and interpret the measured force and displacement signals.

scholarly journals A Method For Cutting And Preparing Thin-Sections Of Frozen Soil

1977 ◽  
Vol 18 (78) ◽  
pp. 143-144 ◽  
Author(s):  
T.E. Osterkamp
Keyword(s):  
Cutting Forces ◽  
Frozen Soil ◽  
Operating Conditions ◽  
Operating Parameters ◽  
Thin Sections ◽  
Diamond Wire ◽  
Wire Saw ◽  
Diamond Wire Saw ◽  
The Wire

Abstract A diamond wire saw was modified for cutting thin sections of frozen soil and suitable operating conditions were determined experimentally. It was found that a lubricated wire, 0.34 mm in diameter, operaied at cutting velocities of 100-300 mm s-1 and cutting forces 0.02-0.1 kg produced smooth cut surfaces un thin sections 0.4-0.5 mm in thickness. The; temperature and wire size were not critical operating parameters and the wire tensions recommended by the manufacturer were satisfactory. A method of mounting the thin sections is also described.

Fault Detection With NURBs-Based Metamodels

2006 ◽  
Author(s):  
Cameron J. Turner ◽  
Abiola M. Ajetunmobi ◽  
Richard H. Crawford
Keyword(s):  
Current System ◽  
Cost Savings ◽  
Operating Conditions ◽  
Engineering Systems ◽  
Brushless Dc Motors ◽  
Brushless Dc ◽  
Dc Motors ◽  
Modern Engineering ◽  
Incipient Faults ◽  
A Current

Developing the ability for a system to self-monitor its condition is a desirable feature in many modern engineering systems. This capability facilitates a maintenance-as-needed rather than a maintenance-as-scheduled paradigm, offering potential efficiency improvements and corresponding cost savings. By using continuously updated Non-Uniform Rational B-spline (NURBs) metamodels of system performance to monitor the system condition, the onset of incipient faults can be detected by comparison to a self-generated as-built system metamodel, providing a basis for determining off-normal operating conditions. This capability is demonstrated for three distinct fault conditions prevalent in brushless DC motors. The results show that this technique can be used to develop an as-built system metamodel, develop a current system model during system operation, and detect the presence of an incipient fault condition despite the compensation provided by a feedback control system.

Quantitative Measurement of Pantograph Loss of Contact Dynamics

2013 ◽  
Author(s):  
Bih-Yuan Ku ◽  
Jen-Sen Liu ◽  
Ming-Jan Ko
Keyword(s):  
Quantitative Measurement ◽  
Photovoltaic Cells ◽  
Quantitative Measure ◽  
Contact Dynamics ◽  
Term Operation ◽  
Current Collection ◽  
Voltage Signal ◽  
Loss Of Contact

In this paper we present our work on the development of a quantitative measurement advice to capture the dynamics of pantograph arcing during loss of contact. Despite the difficulties involved, it is very important for the railroad operators to accurately measure the pantograph loss-of-contact dynamics in order to assess the current collection quality of the pantograph with the overhead contact system during the commissioning phase and long-term operation. We use photovoltaic cells to construct a simple but effective sensor that can produce a voltage signal proportional to arc strength and duration, which can then be used as a precise quantitative measure of the loss of contact dynamics of the pantograph.

scholarly journals Innovative doubly-fed freight electric locomotive 2EV120 “Knyaz’ Vladimir”

2018 ◽  
Vol 239 ◽  
pp. 01001
Author(s):  
Kirill Domanov
Keyword(s):  
Traffic Control ◽  
Performance Indicators ◽  
Single Phase ◽  
Operational Reliability ◽  
Optimal Combination ◽  
Operating Conditions ◽  
Electric Locomotive ◽  
The World ◽  
Doubly Fed ◽  
Electric Braking

The paper considers a new doubly-fed freight electric locomotive taking into account the world experience of locomotive construction, the regulatory base and operating conditions on the railways of Russia. Its parameters are presented: the main technical characteristics in comparison with currently used electric locomotives of new series, standard traction characteristics, and the characteristic of electric braking. Features of the design of the units and parts of the undercarriage and brake equipment are given. The studied doubly-fed freight electric locomotive is designed taking into account the optimal combination of equipment backup capabilities and increased operational reliability with minimization of the failure flow causing the withdrawal of two or more traction axles due to the faults. It has promising possibilities for replacing outdated locomotives with alternating and direct current, operated on sections with changing and adjacent stations, electrified on a constant and single-phase alternating current in the places where such sections are joined to the extent of the organization of traffic control according to the principles of working domain technologies. In this case, the joints between the two types of the train current can pass nearly without stopping, their running time is shortened, and the performance indicators are improved.

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