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Railay internship report


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on traction motor

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Railay internship report

  1. 1. Report on TRACTION MOTOR S.E.Railway, Diesel loco shed, Bondamunda In partial fulfilment of the requirements for the degree BachelorofTechnology Submitted by: Subham Gahir B.TECH 2015-2019 Regdn no.:1541016368 Institute of Technical Education and Research
  2. 2. Declaration I certify that this report is prepared based on summer internship project under taken by me in S.E.Railway, Diesel loco shed, Bondamunda from 1st june to 30th june,2018 under the guidance of every department’s employees. In partial fulfilment of the requirements for the degree Bachelor of Technology (B.TECH) from Institute of Technical Education and Research, Siksha O’ Anusandhan university,Odisha. Submitted By: Name: Subham Gahir ____________________ Signature Date:
  3. 3. Acknowledgement “Gratitude is the hardest of emotion to express and often does not find adequate ways to convey the entire one feels.” Summer training is the one of the important part of B.TECH course, which has helped me to learn a lot of experiences which will be beneficial in my succeeding career. For this with an ineffable sense of gratitude I take this opportunity to express my deep sense of indebtedness to Respected Prof. Abhisek Pattnaik ,Placement Director of Institute of Technical Education and Research who has provided me an opportunity to learn and know more about Indian railways. I am also very much thankful to the employees of various department for their interest, constructive criticism, persistent encouragement and untiring guidance throughout the summer training. It has been my great privilege to work under these inspiring guidance.
  4. 4. Content Introduction to diesel loco shed bondamunda Locomotive and its type Diesel electric locomotive DC system of electrification Traction motor Three phases Induction Motor for Traction application Conclusion Bibliography
  5. 5. Introduction to diesel loco shed bondamunda Diesel loco shed, Bondamunda is situated in the picturesque hilly surroundings to the vicinity of Saranda forest in its North, east and south side and west side by Rourkela steel city spreading over land of 50 acres, out of which 9492 Sq. Meters is covered area. This holds the distinction of being one of the oldest diesel loco sheds of Indian Railway. The Shed is at about 8 km from Rourkela Railway Station, and is well connected by road as well as Rail to other parts of the Country. Diesel Shed, Bondamunda is being functioning continuously in full fledged manner since October’1962, is presently the one premier Shed of S.E.Railway as well as of Indian Railway .The shed caters to the traffic needs of CKP, KGP, SBP, KUR, VSKP, RNC, ADA, BSP and R division. Presently the shed is providing about 32 MU consisting of 18 nos. ALCO locomotives MU’s and 14 nos.HHP i.e. WDG4 MU’s along with 20 nos. single locomotives. In addition to this 08nos. of WDS6 loco is being provided to traffic for shunting and other miscellaneous operations. Beside this the shed also maintaining 31 locomotives for coaching services. All the locomotives of this shed are equipped with Micro processor based control system. The present loco holding profile of this shed is as follows. WDG-3A : 52 WDM-3A : 30 WDM-3D : 15 WDG-4 : 34 WDS-6 : 08 TOTAL : 139
  6. 6. Locomotive and its type Locomotive is an automatic device which kept on steel frame having ability to run on rails and has power to pull passenger as well as goods trains. Locomotives are of three types : (1) Steam Locomotive (2) Diesel Electric Locomotive (3) Electric Locomotive
  7. 7. Dieselelectric locomotive Diesel electric locomotives were introduced firstly in united states in 1924 and have become the most widely used type of locomotive. It was introduced for first time in India in 1958. Diesel electric locomotive has electric drive in form of traction motors driving the axles and controlled with electronic controls. It differs from electric locomotives principally in that it has its own generating station instead of being connected to a remote generating station through overhead wires. The generating station consists of a large diesel engine coupled to dc generator that provides power to traction motors. These motors drive the driving wheels.
  8. 8. Advantages: (a) It provides high starting acceleration in comparison to steam locomotive. (b) It is more efficient than a steam locomotive. Disadvantages: (a) It is costlier than either steam or electric locomotive for same power. (b) Life of diesel engine is shorter comparatively. (c) Regenerative braking cannot be employed though rheostatic can be. (d) Overload capacity is limited because diesel engine is a constant output prime mover. DC system of electrification In dc system with overhead catenary, dc traction motors are supplied 1500 V DC by catenary. In overhead electrification systems, electricity is supplied through an overhead system of suspended cable which is known as catenary. Indian Railway uses catenaries of constant tension type. At one end of each section of catenary the cable connects to a pulley by going over this ,is terminated by hanging a weight. Catenary wires are usually made of copper alloys such as cadmiumcopper which has high tensile strength of 63 kg per sequare mm. For transmission of 1500 V DC by overhead wire, substations are made and they are located 40 km apart with each other. These substations receive power from 132 kv ,3-phase network. At these substations, this high-voltage 3-phase supply is converted into low-voltage 1-phase supply with help of Scott- connected 3-phase transformers. Next this low voltage ac is converted into 1500 V DC by using suitable rectifiers. The dc supply so obtained is fed to dc traction motors via suitable contact. Advantages of dc system over 1-φ ac system: (a) DC system does not cause electrical interference with overhead communication lines. (b) DC motors are better suited for frequent and rapid acceleration of heavy trains than ac motors. (c) DC train equipment is lighter, less costly and more efficient than similar ac equipment. (d) When operating under similar conditions, dc trains consumes less energy than 1-φ ac train. Disadvantage: Only one disadvantage is the necessity of locating ac/dc conversion substations at short distance apart.
  9. 9. Traction motor (1) Description: The traction motor is a four pole DC series motor in which field winding is connected in series with armature. It is a forced ventilated machine arranged for axle mounting on sleeve bearing. Transverse movement is limited by the flanges of axle suspension bearing. An electric locomotive as well as diesel-electric locomotive in Indian railway contain six dc traction motors at once.
  10. 10. (2) Construction: The armature core is made from high permeability silicon steel stampings and these stampings are separated by thin coating of varnish as insulation with each other. The armature is lap wounded with 100% equalization. The commutator is built up with hard drawn silver bearing copper segment which are insulated with micanite segment. After the commutator is statically and dynamically seasoned to insure stability ,the complete armature is dynamically balanced. The high permeability cast steel magnet frame is machined to insure alignment of the end shields, pole bores & axle way bores. The main poles are built from steel laminations. There are four brush holder per motor, each carrying 3 split carbon brushes. Each brush holder is carried on two insulated support pins. The armature is supported on grease lubricated roller bearing. Bearing assemblies are sealed type, so necessity of lubrication in about 2 or 3 years.
  11. 11. (3) Rating: A traction motor has following ratings: Voltage - 285 volts Current - 980 ampere Speed - 360 rpm Power - 248 kw (4) Principle: When a current carrying conductor is placed in a magnetic field, a force is exerted on it and direction of force is determined by fleming’s left hand rule. In a dc motor, dc supply is provided to field winding. As a result, unidirectional magnetic field is produced and magnetic field lines cut the rotor conductors which carry current equal to field current. Since the conductors are on circumference of rotor, force acts in tangential direction to the rotor. Thus a torque is developed on the rotor and it starts to rotate. (5) Operation: To understand the operation of a traction motor, three transition panels are studied. Transition panels perform transition events. These events correspond to field weaking and changing the connections of traction motor. Three transition panels are performed at three different speeds – First transition at 30 km/hr speed Second transition at 50 km/hr speed Third transition at 80 km/hr speed When 1500 V dc supply is provided to circuit of traction motors, a large current flows through armature of motor as it is connected in series with field. As a result armature, armature begins to rotate and a back emf is generated which opposes the main supply voltage. ( back emf Eb = PφNZ/60A Eb α N ) As speed increases, back emf also increases and it offers resistance to flow of generated current to traction motors. Hence for increasing the speed , the supply voltage must increase but it is not possible to increase supply above 1500 V. Therefore, when speed is reached at 30 km/hr, first transition panel is switched on. Now a parallel combination of two series connected traction motors is under operation and resistance is connected in parallel with the field of motors to refuse back emf. Now speed increases beyond 40 km/hr and back emf again starts increasing rapidly. So second transition panel is switched on at speed of 50km/hr. After second transition, all six motors run in parallel without resistance parallel to field of motors. No longer back emf is controlled by second transition panel as speed increases beyond 70 km/hr, so third transition panel is switched on at speed of 80 km/hr. By this transition, resistances are connected parallel with field of motors in circuit of second transition to reduce back emf.
  12. 12. (6) Speed-Torque characteristic: The speed Vs torque characteristic of dc series traction motor with a constant votltage supply is shown on right side.As the speed decreases, torque for motor increases sharply. As load is removed from motor, speed increases sharply. Hence it must have a load connected. (7) Braking: Dynamic or rheostatic braking is employed for electric locomotives. During the time of braking, traction motors are disconnected from supply and is connected to a dynamic resistance. Now traction motors are acted as traction generator because kinetic energy is converted into electrical energy. The direction of current is reversed during this period as before braking. Field current also reverses as field winding is connected in series with armature. Hence connections of field winding should be changed such that current flows in it in should be changed such that current flows in it in same direction as before braking. The output of generator is given to grid resistance and it dissipates power as heat. Due to friction between wheel and track, a opposite torque is developed. As a result, locomotive stops. If connections of field winding is not revesed, no braking will occure. Dynamic resistance must be less than critical resistance otherwise generator will not be self exciting.
  13. 13. Three phases Induction Motor for Traction application Right from the introduction of electric traction, there was a strong desire to use Three phases Induction Motor for Traction application. This could only be possible with the introduction of variable voltage variable frequency control. Working Principle of Three Phase Induction Motor AC induction motor is equivalent to Transformer where secondary is short circuited and free to rotate. Three phase primary winding is mounted on Stator distributed spatially at 120 degree. Resultant Field flux produced in the air gap, due to time and space varying each phase flux, is of constant magnitude but rotating at a synchronous speed of Ns. The value of Ns is given by 120(f/P ) where f is frequency and P is number of poles. This flux induces emf and current in the rotor and causes it to rotate in the direction of stator flux and tries to catch it up. The induction of voltage and current in the rotor circuit will depend upon the relative motion between field and rotor. The induced emf, rotor reactance and frequency is having value of sE, sX and sf where s is called slip frequency given by (Ns-Nr)*100/Ns
  14. 14. Conclusion Training helps in problem solving. Training helps in creating self awareness. Training is necessary for the progressive development of an individual. Training is an instrument that brings desired change .Training is a means of increasing organizational technical skills. Training helps in the overall development and improvement of person. Everyone should be motivated to attend the training. The training programme should be periodically evaluated and improved.
  15. 15. Bibliography