Presentation on theme: "Traction Control of Electric Locomotives"— Presentation transcript:
1Traction Control of Electric Locomotives TECHSEM REPORTPresented byDinesh Kumar Das Roll # EEUnder the guidance ofMr Shyamalendu Mohanty
2INTRODUCTIONDriving forward of vehicle is called Traction and the system, which employs this type of mechanism is called Traction systemclassified broadly into two groups namely:(1)non-Electric traction systems(2)Electric traction systems
3Requirements of an Ideal Traction System High starting pulling effort in order to have rapid acceleration.Equipment capable of withstanding large temporary overloads for short periods.The locomotive should be self contained and able to run on any route.Capability of withstanding voltage fluctuations and temporary interruption of supply.Parallel running usually more than one motor (two or four motors ) should be possible.
4ADVANTAGE OF ELECTRIC TRACTION . Cheapness. It is cheapest method of all other methods of traction.Cleanliness. It is free from smoke and flue gassesMaintenance cost. Maintenance and repair cost is about 50% of steam traction system.Starting time. It can be started without loss of time.High starting torque. This system uses of d.c. and a.c. series motors which has a very high starting torque.Braking. In electric traction , regenerative breaking is used which feeds back 40%of the energy.Saving in high grade coal. No coal is required for electric traction.
5DISADVANTAGE OF ELECTRIC TRACTION Higher initial expenditure.Failure of supply is a problem.Additional equipments are required for breaking purposes.The electrically operated vehicles have to move only on electrified track.Interference with telegraphs and telephone lines.
6COMPONENTS OF AN A.C LOCOMOTIVE CATENARY - This is the overhead wire of special cross-section.PANTOGRAPH - This is a device used for collecting current from the catenary i.e. the over head lines.CIRCUIT BREAKERS - The function of circuit breaker is to disconnect the engine from the line side in case of some faultON LOAD TAP CHANGER - On load tap changer is used for varying the output voltage for controlling the speed of motorTRANSFORMER - A tap changing transformer is installed in the locomotive for stepping down the voltage according to the requirement of traction motorsRECTIFIERS - Semiconductor rectifiers are used for conversion of A.C power into D.C powerSMOOTHING REACTORS - Any ripples found on the output side of the rectifier are eliminated by the smoothing reactor fitted after the rectifier.
7SEPEXShort form of SEParate EXcitement of traction motors where the armature and field coils of an electric motor are fed with independently controlled current. This has been made much more useful since the introduction of thyristor control where motor control can be much more precise. SEPEX control also allows a degree of automatic wheel slip control during acceleration
8THYRISTOR CONTROLSchematic of AC Electric Locomotive Power System with Thyristor Control and Separately Excited DC Motors
9DC ChoppersThyristor Control Circuit for DC Supply to DC Motors
10Schematic of Single Phase AC Supply Powering 3-Phase AC Motors AC TRACTION MOTORAC Locomotives with AC DriveSchematic of Single Phase AC Supply Powering 3-Phase AC Motors
11AC Locomotives with DC Drives Schematic of AC locomotive with Tap Changer Control of Transformer Output
12DC TRACTION MOTORIt consists of two parts, a rotating armature and a fixed field.The fixed field consists of tightly wound coils of wire fitted inside the motor caseThe armature is another set of coils wound round a central shaft.The armature is connected to the field through "brushes" which are spring loaded contacts pressing against an extension of the armature called the commutator.
13The DC Traction Motor: How it Drives the Axle How a DC motor drives the axle through a pinion and gearwheel
14DC Resistance ControlSimplified DC Traction Motor Power Control Circuit
15DC Power CircuitSchematic of Simple DC Traction Motor Power Control Circuit
17Braking in traction motors Dynamic Braking: where the motors become generators and feed the resulting current back.It classified into two categories:1 Plugging2. Rheostatic Braking3. Regenerative BrakingPLUGGING: Generally plugging is applied by changing the phase sequence of the three phase induction and synchronous motor
18Rheostatic BrakingThe motors become generators and feed the resulting current into an on-board resistance.When the driver calls for brake, the power circuit connections to the motors are changed from their power configuration to a brake configuration and the resistors inserted into the motor circuit. As the motor generated energy is dispersed in the resistors and the train speed slows, the resistors are switched out in steps, just as they are during acceleration.
19Regenerative Brakingthe motors become generators and feed the resulting current back into the supply systema train could use its motors to act as generators and that this would provide some braking effect if a suitable way could be found to dispose of the energy.Trains were designed therefore, which could return current, generated during braking, to the supply system for use by other trains.
20CONCLUSIONno single motor is ideal for traction purposes. But; DC Series Motors are most suitable for this workPower Electronics have been resorted to in a major way as in case of thyristor control.Different types of braking for the traction system was studied.