12-07-2014, 01:16 PM
diesel locomotive works Varanasi
diesel locomotive.ppt (Size: 1.87 MB / Downloads: 128)
Introduction
It is a production unit owned by Indian railways , for which it manufactures diesel–electric locomotive and its spares parts.
To meet the increased transportation needs of the Indian railways it was established in collaboration with M\s ALCO( American Locomotive Company), USA.
Founded in 1961, the D.L.W. rolled out its first locomotive three year later, on January 3, 1964. It manufactures locomotives which are variants based on the original ALCO design dating to 1960s and the GM EMD design of the 1990s.
It has evolved into an integrated diesel–electric locomotive manufacturing plant, capable of building all components of the locomotive in-house, including the engines, super structures, and fabricated bogies and under frames.
Diesel’s advantages over steam
They can safely be operated by one person, making them ideal for switching/shunting duties in yards.
The operating environment is much more attractive, being much quieter, fully weatherproof and without the dirt and heat that is an inevitable part of operating a steam locomotive.
Steam locomotives require intensive maintenance, lubrication and cleaning before, during and after use.
The thermal efficiency of steam was considerably less than that of Diesel engines.
PRINCIPLE OF DIESEL ENGINE
When the piston is at the top of its travel, the cylinder contains a charge of highly compressed air.
Diesel fuel is sprayed into the cylinder by the injector and immediately ignites because of the heat and pressure inside the cylinder.
The air in the cylinder is raised to about 500-600 psi which raises the temperature inside to about 1000 0 F.
The pressure created by the combustion of the fuel drives the piston downward. This is the “power stroke”.
components in diesel engine
1. Valves : For a two-stroke engine, there may simply be an exhaust outlet and fuel inlet instead of a valve system.
2. Exhaust systems: The exhaust system frequently contains devices to control pollution, both chemical and noise pollution.
3. cooling systems: Combustion generates a great deal of heat, and some of this transfers to the walls of the engine. Cooling systems usually employ air or liquid (usually water) cooling.
4. Piston: It is located in a cylinder and is made gas-tight by piston rings. Its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. In two-stroke engines the piston also acts as a valve by covering and uncovering ports in the cylinder wall.
5. Crank shaft: Most reciprocating internal combustion engines end up turning a shaft. This means that the linear motion of a piston must be converted into rotation. This is typically achieved by a crankshaft.
6. Starter systems : All internal combustion engines require some form of system to get them into operation. Most piston engines use a starter motor powered by the same battery as runs the rest of the electric systems.
7. Lubrication Systems: Internal combustions engines require lubrication in operation that moving parts slide smoothly over each other. Insufficient lubrication subjects the parts of the engine to metal-to-metal contact, friction, heat build-up etc.
Diesel-electric locomotive
In a diesel-electric locomotive, the diesel engine drives an electrical generator or alternator whose output provides power to the traction motors. There is no mechanical connection between the engine and the wheels. The important components of diesel-electric propulsion are :
Diesel engine ( 16 cylinder , two stroke )
The main generator or alternator
Traction motor
Control system consisting of the engine governor
Electrical or electronic component to control or modify the electrical supply to the traction motions
Inverters
Governor
A device used to measure and regulate the speed of an engine.
The microcontroller based governor consists of a control unit mounted in the drive cab and an actuator unit mounted on the engine.
The governor controls the engine speed based on throttle handle position.
Engine RPM is measured by a Tacho generator or engine speed sensor mounted on the engine.
Digital PID control is used to control the fuel rack position dynamically , based on the selected notch on throttle handle and measure engine RPM . A steeper motor drive is used to control the fuel rack of diesel engine .
A PID controller attempts to correct the error between a measured process variable and a desired set point by calculating and then outputting a corrective action that can adjust the process accordingly and rapidly, to keep the error minimal.
The governor also controls the electrical load on the engine, so as to limit horsepower at each notch to a present level, through an electrical interface with the excitation system of the locomotive.
Air pressure is measured through a pressure sensor mounted in air manifold, and movement of fuel rack is limited as a function of this pressure so as to prevent incomplete combustion, black smoke, excessive engine temperature, fuel wastage etc.
Lube oil pressure is continuously monitored and engine is shut down if the lube oil pressure is less than the specified pressure so as to protect the engine from damage due to malfunctioning of lube oil pump etc.
rectifiers
A rectifier is an electrical device that converts AC to DC, a process known as rectification. Rectifiers have many uses including as components of power supplies and as detectors of radio signals.
A device which performs the opposite function (converting DC to AC) is known as an inverter.
Rectifiers are of two types:
a) half wave rectifier
b) full wave rectifier
Telephone exchange
Provides telephone connections to the D.L.W. administrative blocks and D.L.W. colony area.
The exchange is also provided with rack type Main Distribution Frame (M.D.F.). This has capacity to mount fuse mounting with fuses and test jacks.
The exchange is designed to perform satisfactorily for a line loop resistance of 1000 ohm for each subscriber.
The local loop is the physical link or circuit that connects from the demarcation point of the customer premises to the edge of the telecommunications service provider's network.
The exchange works on D.C. supply of 50 volts obtained from battery set which is connected in parallel to the charger which is operating on 230 volts A.C.
The voltage required when two subscriber talks is 12 volts.
Electromagnetic interference :
It is a disturbance that affects an electrical circuit due to either electromagnetic radiation emitted from an external source.
The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit.
In balanced pair operation, the two wires carry equal and opposite signals and the destination detects the difference between the two.
Distribution pole
DP is much nearer to the consumer where it is easier to take cable from the consumer.
Electric repair shop
Calibration
Calibration is a comparison between measurements-one of known magnitude or correctness made or set with one device and another measurement made in as similar a way as possible with a second device. The device with the known or assigned correctness is called the standard. The second device is the unit under test (UUT), test instrument (TI).
water testing
Water acts as a coolant for moving part of the engine because constant movement or rotation causes various parts to heat up and water working as coolant cooled down the concerned part.
Load testing
For load testing electrical load is provided to the engine. If there is any abnormal sound then the engine is again tested for lubrication so that any flaw which is there can be removed.