Electric Traction System benefits and different types of electric traction system.

It contains different types of electric traction systems and their benefits along with advantages and disadvantages.

1. Seminar on Electric Traction System Under the guidance of :- Dr.IMRAN KHAN (Dept. of EE) AZAD TECHNICAL CAMPUS, LUCKNOW Presented by :- AMIT KUMAR Roll No.- 1605320659 Course:- B.Tech (EE) 3 rd Year

2. CONTENTS INTRODUCTION WHY ELECTRIC TRACTION SYSTEM? TYPE OF ELECTRIC TRACTION TYPE OF TRACK ELECTRIFICATION SINGLE CATENARY CONSTRUCTION SYSTEM OF TRACK ELECTRIFICATION MAJOR COMPOTENTS COMPONENTS OF AN A.C LOCOMOTIVE CONCLOUSION

3. Introduction The process of moving any vehicle is called traction. If the Electric energy is use in this process is called electric traction. Classified broadly into groups namely: Non-Electric traction system/Mechanical traction system:- Traction system do not involve the use of electricity such as steam engine drive , IC engine drive etc. Electric Traction system:- The system which use electrical power for traction system i.e for railways , trams trolleys , etc. called electric traction.

4. WHY ELECTRIC TRACTION SYSTEM? Cheapness : Low operation cost. Cleanliness: Smoke and gas free. Maintenance cost: 50% less than other steam system. Starting time and speed: Without loss of time. High starting torque: Use of D.C & A.C series motor- Very high starting torque. Braking: Regenerative breaking is used which feedback energy. Saving in high grade coal: Saving of non-renewable energy source.

5. TYPE OF ELECTRIC TRACTION SYSTEMS

6. DC Traction DC traction units use direct current drawn from conductor rail or an overhead lines. The most popular line voltage for overhead wire supply systems-15kV DC and 30kV DC. 600V-750V DC volt range is used for third rail systems (additional rail is provided for supplying electricity to train and is called conductor rail). Disadvantage:- Expensive substations are required at frequent intervals. The overhead wire or third rail must be relatively large and heavy. Voltage goes on decreasing on decreasing with increase in length

7. AC Traction AC Traction units draw alternating current from an overhead line. Typical Voltage Used are:- 25kV AC, 50 HZ 25kV AC, 60 Hz Advantages:- Fewer substations are required. Lighting overhead current supply wire can be used. Reduced capital cost of electrification Reduced weight of support structure.

8. Multi-Systems Multi-system trains are used to provides continuous journeys along routes that are electrified using more than one system. One way to accomplish this is by changing locomotives at the switching stations. These stations have overhead wires that can be switch from one voltage to another. Another way is to use multi-system locomotives that cam operates under several different voltage and current type.

9. System of Track Electrification Trolley wire or contact wire- suspended with of sag so that contact between the trolley wire and current collector can be maintained at high speeds. This wire is supported by another wire known as catenary. Two different type of catenary construction can be used. Single Catenary Compound Catenary

10. Single Catenary Construction Provided for speed up to 120kmph. Span of catenary wire 45-90m and sag of 1-2m Relatively cheaper Less maintenance Suitable where traffic is danger more and operating speeds are low Compound Catenary Construction Provided for speeds range 190-224kmph Additional wire called intermediate wire is use to increase current carrying capacity i.e to have increase traffic density Type of Track Electrification

11. Single Catenary Construction

12. Types of current collector Bow collector:- A bow collector is one of the three main device used on tramcars to transfer electric current from the wire above to the tram below . It has now largely replaced by the pantograph Pantograph collector:-Main function is to maintain the link between overhead contact wire and power circuit of the locomotive at varying speeds in different climate and wind condition

13. MAJOR COMPONENTS TRACTION SUBSTATION OVERHEAD WIRING CURRENT COLLECTOR TRACK TRACTION SYSTEM (VEHICLE)

14. COMPONENTS OF AN AC LOCOMOTIVE

15. Parts of Electric Locomotive TRAMSFORMER The line voltage has to be stepped down before use on the train. Traction Transformer for trains and railway stock transform the overhead contact line voltage ,which ranges mainly from 15kV or 25kV to voltage (0.7kV and 1.5kV). Normally Transformer use are of rating 5600kVA to 7200kVA

16. RECTIFIER A rectifier consists of thyristors and diodes which is used to convert AC to DC Instead of conventional bridge rectifier thyristors are used. A modern locomotive usually have at least two “Main Rectifier”. Vd.c=2Vmax/ =0.637Vmax=0.9Vrms  

17. INVERTER The inverter are used for converting Dc power from a fixed voltage DC supply into an AC output voltage of variable frequency and fixed or variable output AC voltage.

18. DC Link Used on modern electronic power system between the 1- phase rectifier and 3-phase inverter. It is easier to convert the single phase AC from the overhead line to the 3-phase required for the motors by rectifying it to DC and then inverting the dc to 3-phase AC.

19. Train Lighting/Air Conditioning(TL/AC) Axel-driven generators are use to store batteries that power light , fans and electrical fittings. For powering air-conditioning equipment , an inverter was used to convert the DC output of a set of batteries to 415V AC. Older coaches use bank of 24V batteries while 110V in newer coaches. In may air-conditioned coaches, a ‘mid-on generator’ (MOG) is used.

20. DC Series motor Develops high torque at low speeds and low torque at high speed, exact requirement of the traction units. Torque is independent of the line voltage and thus unaffected by the variations in the line voltage.

21. Single phase AC series motor Starting torque is lower than dc series motor due to poor power factor at starting. Maximum operating voltage is limited to 400 Volts.

22. Three Phase Induction Motors- Provides constant speed operation, developing low starting torque drawing high starting current and complicated control networks makes it unstable for electric traction work. Automatic regeneration is the main advantage in electric traction with the motor.   T=(3/2 N S )*sE 2 2 R 2 /R 2 2 +(sX 2 ) 2 Where ,E2 is the rotor EMF R2 is the rotor resistance X2 is the rotor inductive reactance s=Slip of the induction motor  

23. ELECTRICAL BRAKING We can say that it is the process of reducing speed of any rotating machine . Classified into three categories- Plugging Rheostatic breaking Regenerative Breaking Plugging – Plugging is applied by changing phase sequence of synchronous or induction motors. The main disadvantage of this method is that here power is wasted.

24. 2) Rheostatic breaking- Connection are made change from power configuration to break configuration and resistor are inserted in the motor. 3) Regenerative breaking- Motor become generators and feed resulting current back into supply system.

25. Conclusion No single motor is ideal for traction purpose. DC series motor are most suitable for this work. Power electronic has been restored to in a major way for conversion and control operations. Different type of braking were discussed out of which regenerative most efficient. Through electric locomotive are more efficient the steam and diesel locomotives.

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