comparison between ac and dc traction pdf

Comparison Between Ac And Dc Traction Pdf

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Rail transport is coming back into favour for the transportation of goods over long distances. This article takes a look at the role that electric motors play in this sector of the transport industry.

Electric motors play an essential role in almost every industry. Using the right type of motor with high-quality parts and regular servicing keeps your facility running smoothly and prevents damage to the endpoint equipment due to wear or power surges. Gainesville Industrial Electric can help your company select the right industrial electric motors and parts for your applications. Electric motors are machines that convert electrical energy—from either stored power or a direct electrical connection—into mechanical energy through the production of rotational force.

AC Traction vs DC Traction

A traction motor is an electric motor used for propulsion of a vehicle, such as locomotives , electric or hydrogen vehicles , elevators or electric multiple unit. Traction motors are used in electrically powered rail vehicles electric multiple units and other electric vehicles including electric milk floats , elevators , roller coasters , conveyors , and trolleybuses , as well as vehicles with electrical transmission systems Diesel-electric Locomotives , electric hybrid vehicles , and battery electric vehicles. Direct-current motors with series field windings are the oldest type of traction motors. These provide a speed-torque characteristic useful for propulsion, providing high torque at lower speeds for acceleration of the vehicle, and declining torque as speed increases. By arranging the field winding with multiple taps, the speed characteristic can be varied, allowing relatively smooth operator control of acceleration. A further measure of control is provided by using pairs of motors on a vehicle in series-parallel control ; for slow operation or heavy loads, two motors can be run in series off the direct-current supply. Where higher speed is desired, these motors can be operated in parallel, making a higher voltage available at each and so allowing higher speeds.

So in the full-bridge method we have two SCRs for any input phase. By applying low voltage to the gates the SCR turns on. Applying the voltage to the gate at a different angle of the input phase, the output current varies and thus the drive can control the motor speed. To verify the motor speed, and compensate if necessary, most DC drives require the motor to have a tachometer as a feedback. Higher motor speed generates more voltage in the tachometer and the drive references this voltage to make sure the motor is running at the correct speed per user settings. Smaller DC motors have a permanent magnet field while larger DC motors have a separate coil inside the motor, known as field, which eliminates the need of a permanent magnet which are expensive to construct in the motor.

AC and DC Motors | Types of Electric Motors and Applications

The electric traction system is the most efficient of all other traction system such as steam and internal combustion IC engine type systems. It offers several benefits over other systems, including quick start and stop, very efficient, pollution-free, easy to handle and easy speed control. With the advancement of electrical drives for traction systems, this electrification of traction becomes much popular in several traction services including metro or suburban railways. A system which causes the propulsion of vehicle in which tractive or driving force is obtained from various devices such as diesel engine drives, steam engine drives, electric motors, etc. It can also be defined as the railway vehicle that provides the necessary traction power to move the train is referred as the traction or locomotive. This traction power can be diesel, steam or electric power.

A railway electrification system supplies electric power to railway trains and trams without an on-board prime mover or local fuel supply. Electric railways use either electric locomotives hauling passengers or freight in separate cars , electric multiple units passenger cars with their own motors or both. Electricity is typically generated in large and relatively efficient generating stations , transmitted to the railway network and distributed to the trains. Some electric railways have their own dedicated generating stations and transmission lines , but most purchase power from an electric utility. The railway usually provides its own distribution lines, switches, and transformers. Power is supplied to moving trains with a nearly continuous conductor running along the track that usually takes one of two forms: an overhead line , suspended from poles or towers along the track or from structure or tunnel ceilings, or a third rail mounted at track level and contacted by a sliding " pickup shoe ".

Difference Between AC and DC Motor

Present scenario of Indian Railways — High speed traction, Metro, Latest trends in traction-Metro, monorail, Magnetic levitation Vehicle, Steam, diesel, diesel-electric, Battery and electric traction systems, General arrangement of D. Analysis of speed time curves for main line, suburban and urban services, Simplified speed time curves. Features of traction motors. Traction motors-single phase, Three phase, Linear Induction Motor, Comparison between different traction motors, Series-parallel control, Open circuit, Shunt and bridge transition, Pulse Width Modulation control of induction motors, Types of electric braking system. Important features of electric locomotives, Different types of locomotives, Current collecting equipment, Coach wiring and lighting devices, Power conversion and transmission systems, Control and auxiliary equipment.

The AC Motor and the DC Motor are differentiated on the various factors like the source or the nature of the power used in the motor.

Electric Traction And Control (3350907)

To avoid stray current and maintain the benefit of no phase-split in the DC traction power supply system, an AC traction power supply system was proposed for the urban public transport such as metro and light rail transit. The MSS includes a single-phase main traction transformer and a negative-sequence compensation device, while the CTN includes double-core cables, traction transformers, overhead catenary system, rails, etc. Several key techniques for the proposed system were put forward and discussed, which can be summarized as 1 the power supply principle, equivalent circuit and transmission ability of the CTN, the cable-catenary matching technique, and the selection of catenary voltage level; 2 the segmentation technology and status identification method for traction power supply network, distributed and centralized protection schemes, etc. The proposed industrial frequency single-phase AC traction power supply system shows an excellent technical performance, good economy, and high reliability, hence provides a new alternative for metro and urban rail transit power supply systems. From worldwide application point of view, DC system, low-frequency single-phase AC system, and industrial frequency single-phase AC system are three main power supply systems for trunk railways, metros, and light rails. Each of them has its own characteristics and some comparative advantages changing with the development of electrotechnics [ 1 ]. Today, except the low-frequency single-phase AC system still being used in trunk railways in Germany and some of its neighborhood countries, the DC system and the industrial frequency single-phase AC system have been mainly used around the world.

The AC alternating current Drive, also known as Variable Frequency Drive, has been the standard in industry for many years. While it has been used in locomotives for over two decades especially in Europe , it has only been recently that the price of the drives has allowed them to be used in most of the new diesel-electric locomotives in the United States. The AC drive works by converting the traction alternator output to DC direct current and reconverting it to a variable frequency AC which powers AC traction motors. Because AC motors operate at approximately the frequency of the current, the drives must adjust the frequency so that the motors can have a speed range of zero to maximum rpm. AC traction for locomotives is a major improvement over the old DC systems. The friction coefficient between wheel and rail is usually in the range of. The locomotive adhesion variable represents the ability of the locomotive to convert the available friction into usable friction at the wheel rail interface.


TRACTION MOTOR REQUIREMENTS. There are several practical differences between traction motors and other industrial machines: " traction motors are built​.


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Electric Locomotives. North American Freight Train Brakes. The DC Traction Motor. Historically, the DC motor was the mainstay of electric traction drives on both electric and diesel-electric rolling stock. Many examples are still in use around the world. The motor consists of two parts, a rotating armature and a fixed field Figure 1. The fixed field consists of tightly wound coils of wire fitted inside the motor case.

Никакой пули. Беккер снисходительно покачал головой: - Иногда все выглядит не так, как есть на самом деле. Лицо немца стало белым как полотно. Беккер был доволен. Ложь подействовала: бедняга даже вспотел. - Че-че-го же вы хотите? - выдавил он заикаясь.  - Я ничего не знаю.

 Линейная мутация, - простонал коммандер.  - Танкадо утверждал, что это составная часть кода.  - И он безжизненно откинулся на спинку стула. Сьюзан была понятна боль, которую испытывал шеф. Его так просто обвели вокруг пальца. Танкадо не собирался продавать свой алгоритм никакой компьютерной компании, потому что никакого алгоритма не. Цифровая крепость оказалась фарсом, наживкой для Агентства национальной безопасности.

Выйдя на улицу, Беккер увидел у входа в парк телефонную будку.

Сьюзан протянула карточку и приготовилась ждать обычные полминуты. Офицер пропустил удостоверение через подключенный к компьютеру сканер, потом наконец взглянул на. - Спасибо, мисс Флетчер.

Автобус номер 27 следует к хорошо известной конечной остановке. ГЛАВА 46 Фил Чатрукьян швырнул трубку на рычаг. Линия Джаббы оказалась занята, а службу ожидания соединения Джабба отвергал как хитрый трюк корпорации Американ телефон энд телеграф, рассчитанный на то, чтобы увеличить прибыль: простая фраза Я говорю по другому телефону, я вам перезвоню приносила телефонным компаниям миллионы дополнительных долларов ежегодно. Отказ Джаббы использовать данную услугу был его личным ответом на требование АН Б о том, чтобы он всегда был доступен по мобильному телефону. Чатрукьян повернулся и посмотрел в пустой зал шифровалки.

Одно только ее беспокоило: всякий раз, когда они куда-то ходили, он решительно противился тому, чтобы она сама платила за. Сьюзан не могла с этим смириться, видя, как он выкладывает за их обед свою дневную заработную плату, но спорить с ним было бесполезно. Она в конце концов перестала протестовать, но это продолжало ее беспокоить.

Правильно ли она поняла. Все сказанное было вполне в духе Грега Хейла. Но это невозможно.

4 comments

Goposodmi

Introduction to java programming liang pearson education 7th edition pdf role of natural herbs in the treatment of hypertension pdf

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Antoinette V.

AC traction for locomotives is a major improvement over the old DC systems. The primary advantages of AC traction are adhesion levels up to % greater than.

REPLY

David A.

Control for drive systems, Control of D.C, Induction, and Synchronous motor drives. Traction Motors: Review of characteristics of different types of DC and AC.

REPLY

Demi L.

Which of the following is an advantage of electric traction over other methods of traction?

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