Maximum tractive effort is defined as the highest tractive force that can be generated under any condition that is not injurious to the vehicle or machine. But this last offered a further expansion until which one we know today. The train is accelerated at the maximum possible torque, and the power increases linearly with speed. Typical speed time curve of a train is shown in fig 2. It mainly consists of i constant acceleration period, ii acceleration on speed curve, iii free running period, iv coasting. Lathes, boring mcs, milling mcs, steel mill coiler and electric traction load. A treatise on the application of electric power to tramways and.
From starting to the stage when locomotive attains maximum speed, the period is known as acceleration period, as the vehicle is constantly accelerated. Course outline in this course, a method is described to approximate the motor starting time using the characteristics provided by the manufacturer. Traction energy consumption of electric locomotives and electric multiple units at speed restrictions article pdf available july 2015 with 6,234 reads how we measure reads. Speed time curves for different services trapezoidal and quadrilateral. Speed time, distance time and simplified speed time curves, attractive effort for acceleration and propulsion, effective weight, train resistance, adhesive weight, specific energy output and consumption. General by electric traction is meant locomotion in which the driving or tractive force is obtained from electric motors. Which of the following is an advantage of electric traction over other methods of traction. Practicing all electric traction electrical engineering questions and answers in online helps you to improve your ability to attend the real time gate, ies and bsnl jto exams. In most cases, maximum tractive effort is developed at low speed and may be the same as the starting tractive effort. Function of characteristic curve of dc motors electrical. The time current curve 7 the aa curve 8 clearing integral information factors k and x 8.
The final decade of the 20 th century and the first decade of the 21 st century were marked by the enormous rise in high speed due to the huge leaps forward in electric locomotive technology. Slope of the curve at any point gives the speed at that instant. Overall efficiency of steam locomotive system is close to a 5 to 10% b 25 to 30% c 55 to 60% d 75 to 80%. Which of the following is the disadvantage of electric traction over other systems of traction. I offer a formal definition of headway as, for a single direction, the elapsed time at a given point between the passing of the front. Protecting semiconductors with high speed fuses application guide 10507 effective june 216. There are four distinct periods in it, acceleration period, free running period, coasting period. List the advantages and disadvantages of electric traction. Introduction to train movement and energy consumption 2. For passenger locos, need for the tractive effort is less as compared to speed therefore tractive effort characteristics at. The speed torque curve for other driven equipments such as pumps, fan, blowers will also follow the same below rules only. Full text of speedtime curve study of electric railway. Optimization of energy consumption in electric traction system by. Massachusetts institute of technology 1 introduction this is a concept paper in response to the foa entitled rare earth alternatives in critical technologies for energy react.
Time current curves cables the time current curves for cables are also known as damage curves. In this part, i will explain each period of speed time curve which is most important to exam point of view. The traction motor is suitable for a range of vehicle applications, from medium size passenger cars to light duty commercial vehicles. Sketch the typical speedtime curve for main line service and to sub urban services. Pdf traction energy consumption of electric locomotives and. The mechanics involves conversion of overhead electrical powerdieselsteam power in rail horse power to haul a train encountering acceleration, train, grade, curve resistance and similarly braking. The graph above shows a torque speed curve of a typical d. This curve gives the speed at various time instance after the start of run directly. Electric traction mcqs answers pdf electrical engineering. Utilization of electrical energy and traction 2160907 chapter7.
The speed time curve gives the complete information about the motion of the train. Train movement and energy consumption electrical engineering. Specific traction energies as a function of train speed are presented in fig. Electric traction 1701 however, the steam locomotive suffers from the following disadvantages. Typical square body and round body high speed fuse constructions. Crest speed, average speed and schedule speed of train 4. Utilization of electrical energy pdf notes uee pdf notes unit i electric drives. Review of existing electric traction systems in india. Quadrilateral speed time curve pertains to which of the following services. The speed time curve urban or city service is almost similar to. In suburban service, the distance between two adjacent stops for an electric train is lying between 1 and 8 km. Pdf the objective of this paper is initially to present a basic modeling of the railway traction system.
Speed restrictions are needed because of transport safety due to railway. Special features of traction motor, methods of electric brakingplugging rheostatic braking and regenerative braking. Pdf traction energy consumption of electric locomotives. Explain supply system of electric traction in details. For every motor, there is a specific torque speed curve and power curve. Pdf in this article the author reports the measurements made by traction. The curve may be broadly split into the following periods. Bc this is a constant power line in which tractive effort drops with increasing speed in inverse proportion.
Electric traction electrical engineering questions and. These engines are now being electrictraction 1701 however, the steam locomotive. Pdf basic modeling for electric traction systems under. It is used in electric trains, tramcars, trolley buses and diesel electric vehicles etc. High speed railway capacity v conf railway technical. In this article, we will discuss how to read the speed torque curve. The typical speed time curve for a locomotive is shown in figure given above. In quadrilateral speedtime curve of electric traction. For understanding the speed torque curve we consider a compressor is driven by an electric motor for easy understanding.
Essential driving mechanism of an electric locomotive is shown in fig. In a steam locomotive electric power is provided through a battery system b diesel engine generator c. Small capacity of the batteries and the necessity for frequent charging, speed range is also limited. This curve is lifted upward by overloading traction motor utilising the thermal capacity of the traction motor. Above is a tractive effort curve typical of a new electric train. System of electric traction mechanics of train movement. Discuss in detail about series parallel control of electric traction motor with example. Finding a piece of flat track that isnt busy where they can test its top speed is expensive. Utilization of electrical energy pdf notes uee pdf notes. There are various system of electric traction existing such as electric train, trolley buses, diesel electric vehicles and gas turbine electric vehicles. Out of the two, speedtime curve is more important because 1. Draw the speed time curve related to different traction system. Multiple drive systems per vehicle can be supported due to the safety case and levels of torque integrity employed.
As we all know, it is electric locomoti ves that are at the forefr ont of railway traction, while the diesel locomotive is kept for some very specific uses. Tests experiences in small radius curves of continuously welded rail. If a cross over the tractive effort curve would appear for the next gear by remaining in gear until maximum rpm, then a small, roughly triangular shaped section would be cut out of the available area every time when gear is changed. Some of the technical discussion is based on work that has been reported in a conference publication1. Pdf utilization of electrical energy pdf notes uee. The motor torque versus speed curve, the load torque versus speed curve, and the current versus speed curve are utilized along with the.
Basic modeling for electric traction systems under uncertainty. Electric traction mcqs answers pdf electrical engineering multiple choice questions answers. The control equipment is provided for manual and automatic. Type of electric drives, choice of motor, starting and running characteristics, speed control, temperature rise, particular applications of electric drives, types of industrial loads, continuous, intermittent and variable loads, load qualization.
Unit 1 characteristics of electrical drives speed torque characteristics of various types of loads and drives motors. Full text of speed time curve study of electric railway load conditions see other formats 4 f\ r. A positive, negative and negative b positive, zero and negative c positive, positive and negative d positive, negative and zero. Electric traction system requirements, terms, advantages. This manual covers squirrel cage rotor motor where. The curve drawn between speeding kmhr along yaxis and timing seconds along xaxis is called speed time curve. Electric traction mcq with explanation objective type. Note that torque is inversely proportioal to the speed. I have found in the following graphic the characteristic curve of a locomotive with six dc series wound electric motors at 3000v. The duty cycle of traction drive is explained below with the help of speed time curve and power torque time diagram. Zytek have developed a high power, compact, electric drive package comprising. In electric traction for a trapezoidal speedtime curve. Electric traction has many advantages as compared to other nonelectrical systems of traction includ ing steam traction. The above diagram represents the speed time curve of suburban service.