DLW SUMMER TRAINING REPORT FOR ECE BRANCH

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SUMMER TRAINING
AT
DIESEL LOCOMOTIVE WORK
VARANASI (U.P)
Submitted by:
Subham singh
ECE 3rd
YEAR
NIT DELHI
GUIDED BY:
Mr. Pradeep kumar singh
(principal,TTC)
(2018-19)

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ACKNOWLEDGEMENT
I would sincerely like to thank the employees and the officers of DLW, VARANASI
for their help and support during the vocational training. Despite their busy schedules,
they took time out for us and explained to us the various aspects of the working of the
plant from the production shops.
I would sincerely like to thank Mr. Sudhir Sinha (CWI /TTC)and Mr. Ajay Kumar
(JE/HWS), Mr. Vipin Srivastava (JE/HWS), Mr. Arvind Kumar(JE/HMS),Er. Ravi
Gupta (SSE/HMS) who was instrumental in arranging the vocational training at DLW
Varanasi, and without whose help and guidance the training could not have materialize.
I express my deep sense ofgratitude to Mr Pradeepkumar singh (Principal, TTC)for
given me such a great opportunity.
SUBHAM SINGH
ECE 3RD
YEAR
NIT DELHI

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PREFACE
The objectives of the practical training are to learn something about industries
practically and to be familiar with the working style of a technical person to adjust
simply according to the industrial environment.
It is rightly said practical life is far away from theoretical one. We learn in class room
can give the practical exposer real life experience no doubt they help in improving the
personality of the student, but the practical exposure in the field will help the student in
long run of life and will be able to implement the theoretical knowledge.
As a part of academic syllabus of four year degree course in Electronics and
CommunicationEngineering, every studentis required to undergo a practical training.
I am student of third year Electronics and Communication Engineering and this
report is written on the basis of practical knowledge acquired by me during the period
of practical training taken at Diesel Locomotive Works, Varanasi.

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TABLE OF CONTENTS
CONTENTS PAGE
1. OVERVIEW 5
1.1 ABOUT DLW 5
1.2 LOCOMOTIVES PRODUCED BY DLW 6
1.3 DIESEL LOCOMOTIVE 10
1.3.1 PARTS OF DIESEL LOCOMOTIVE 10
2. WHAT MAKES A DIESEL LOCOMOTIVE WORK? 22
3. MAGNETIC SERVICE SHOP (MSS) 24
3.1 VARIABLE FREQUENCY DRIVE (VFD) 24
3.2 ABOUT PCB AND SMT 28
3.3 ABOUT AC AND WORK 33
3.4 ABOUT 5502A MULTI-PRODUCT CALIBRATOR 35
4. LOCO TEST SHOP (LTS) 37
5. SCADA 39
5.1 WHAT IS SCADA? 39
5.2 COMPONENTS OF TYPICAL SCADA SYSTEM 40
5.3 SCADA FEATURES IN DLW 42
5.4 SCADA SYSTEM ARCHITECTURE IN DLW 43
5.5 DLW INFRASTRUCTURE UNDER MONITORING AND
CONROL
44
5.6 DLW RING 45
5.6 ADVANTAGES OF IMPLEMENTING SCADA SYSTEMS
FOR ELECTRICAL DISTRIBUTION
45
5.7 DLW POWER SUPPLY DIGRAM 46

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CONTENTS PAGES
6. TELEEPHONE EXCHANGE 48
6.1 PRINCIPAL OF TELEPHONY 48
6.2 BASICS OF TELEPHONE 49
6.3 MAIN FUNCTIONAL AREAS IN TELEPHONE EXCHANGE 51
7. CONCLUSION 52
8 .REFERENCE 53

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Chapter 1
OVERVIEW
1.1 About DLW (diesel locomotive works)
a)Brief History
DLW setup as a green field project in technical collaboration with ALCO, USA for
First Locomotive rolled out and dedicated to the Nation in 1994.
manufacture of Diesel Electric Locomotives in 1961.
Entered Export market, first locomotive exported to Tanzania. 5690 locomotives
up to 30th Nov’2009(including 348 EMD locos).
b)ORGANISATION
A flagship production unit of Indian Railways offering complete range of products in its
area of operation with annual turnover of over 2124 Crore. State of the art Design and
Manufacturing facility to manufacture 200 locomotives per annum with wide range of
related products viz. DG Sets, Loco components and sub-assemblies.
Supply of spares required to maintain Diesel Locomotives and DG sets. Unbeatable trail-
blazing track record in providing cost-effective, eco-friendly and reliable solutions to ever
increasing transportation needs for over four decades. Fully geared to meet specific
transportation needs by putting Price - Value - Technology equation perfectly right.
A large base of delighted customers among many countries viz. Myanmar, Sri Lanka,
Malaysia, Vietnam, Bangladesh, Tanzania, Angola, to name a few, bearing testimony to
product leadership in its category.
Staff Status in DLW (As on 1st Oct'2009) Total Staff in DLW 5974, Production Staff
2362
c) MILESTONES
Transfer of Technology Agreement
DLW entered in an agreement with General Motors of USA (now EMD) for technology of
transfer to manufacture high horse-power 4000HP AC-AC GT46MAC and GT46PAC

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locomotives in India making India the only country outside North-America to have this leading
edge technology.
Returns from Transfer of Technology
First PKD WDG-4 locomotive turned out in August 1999.
First DLW built 4000 HP *WDG-4 Freight loco turned out in March 2000.
First DLW built 4000 HP WDP-4 loco turned out in April 2002.
Locomotive design projects
WDG4 locomotive with IGBT base TCC (Siemens & EMD) turned out.
Indigenous AC-AC control for WDG4 (with distributed power controls)
Indigenous AC-AC control for WDP4 (with hotel load capability) WDP4
locomotive with IGBT base TCC & Hotel load capability.
Products of DLW, Varanasi
1) Locomotives- EMD, ALCO
2) DG Sets (Diesel Generating sets)
*Note: Nomenclature (Naming) of DLW Locomotives:
D → Diesel Type
W→ Wide (width of gauge)
G→ Goods
P→Passenger
M→Multipuros
x→ Any numbers in the name represent the horsepower (hp=x×1000)
A→ 100 hp
B→ 200 hp
C→ 300 hp ; and so on...
Hence WDG-3A stands for Wide Diesel Goods- 3100 hp engine & WDP-4 represents
Wide Diesel Passenger- 4000hp
1.2 LOCOMOTIVES PRODUCED BY DLW
BROAD GAUGE MAIN LINE FREIGHT LOCOMOTIVE: WDG 3A

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TECHNICAL INFORMATION
Diesel Electric main line, heavy duty goods service locomotive, with 16 cylinder
ALCO engine and AC/DC traction with micro processor controls
Wheel Arrangement Co-Co
Track Gauge 1676 mm
Weight 123 t
Length over Buffers 19132 mm
Wheel Diameter 1092 mm
Gear Ratio 18 : 74
Min radius of 117 m
Curvature
Maximum Speed 105 Kmph
Diesel Engine Type : 251 B,16 Cyl.-
V
HP 3100
Brake IRAB-1
Loco Air, Dynamic
Train Air
Fuel Tank Capacity 6000 litres
BROAD GAUGE MAIN LINE MIXED SERVICE LOCOMOTIVE: WDM 3D
TECHNICAL INFORMATION
Diesel Electric Locomotive with micro processor control suitable for main line mixed Service
train operation.

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Wheel Co-Co
Arrangement
Track Gauge 1676 mm
Weight 117 t
Max. Axle Load 19.5 t
Length over Buffer 18650 mm
Wheel Diameter 1092 mm
Gear Ratio 18 : 65
Maximum Speed 120 Kmph
Diesel Engine Type : 251 B-16 Cyl. ‘V’ type
(uprated)
HP 3300 HP (standard UIC
condition)
Transmission Electric AC / DC
Brake IRAB-1 system
Loco Air, Dynamic, Hand
Train Air
Fuel Tank 5000 litres
Capacity
WDG4 - 4000 HP GOODS LOCOMOTIVE
BroadGaugefreighttraffic Co-Co diesel electric locomotive with 16 Cylinder 4000HP engine,
AC-AC transmission, microprocessor controlled propulsion and braking with high traction
high speed cast steel trucks.

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Diesel Engine
16 Cylinder 710 G3B, 2 stroke, turbocharged – after cooled Fuel Efficient Engine.
Injection System – Direct Unit Injector
Governor – Woodward
Compression Ratio- 16:1
Lube Oil Sump Capacity – 950 Lts
Transmission
Electrical AC-AC
6 Traction motor ( 3 in parallel per bogie) Suspension –
Axle hung / taper roller bearing Gear Ratio – 90:17
WDP4 – 4000 HP PASSENGER LOCOMOTIVE
State-of-Art, Microprocessor controlled AC-AC, Passenger Locomotive Powered with 16-
710G3B 4000HP Turbo charged Two stroke Engine.
Fabricated rigid design Under frame, two stage suspension, High Traction High Speed
3 axle (HTSC) light weight cast truck frame attribute to high adhesion performance.
Diesel Engine
16 Cylinder 710 G3B, 2 stroke, turbocharged – after cooled Fuel Efficient Engine
Injection System – Direct Unit Injector
Governor – Woodward
Compression Ratio- 16:1
Lube Oil Sump Capacity – 1073 Lts
Transmission
Electrical AC-AC
4 Traction motor ( 3 in parallel per bogie)
Suspension – Axle hung / taper roller bearing

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1.3 The Diesel Locomotive
The modern diesel locomotive is a self contained version of the electric locomotive. Like the electric
locomotive, it has electric drive, in the form of traction motors driving the axles and
controlled with electronic controls. It also has many of the same auxiliary systems for cooling, lighting,
heating, braking and hotel power (if required) for the train. It can operate over the same routes (usually)
and can be operated by the same drivers. It differs principally in that it carries its own generating
station around with it, instead of being connected to a remote generating station through overhead
wires or a third rail. The generating station consists of a large diesel engine coupled to an alternator
producing the necessary electricity. A fuel tank is also essential. It is interesting to note that the modern
diesel locomotive produces about 35% of the power of a electric locomotive of similar weight.
1.3.1.Parts of a Diesel-Electric Locomotive
The following diagram shows the main parts of a US-built diesel-electric locomotive. Click on the part
name for a description.
Diesel Engine
This is the main power source for the locomotive. It comprises a large cylinder block, with the
cylinders arranged in a straight line or in a V (see more here). The engine rotates the drive shaft at up
to 1,000 rpm and this drives the various items needed to power the locomotive. As the transmission is
electric, the engine is used as the power source for the electricity generator or alternator, as it is called
nowadays.
Main Alternator
The diesel engine drives the main alternator which provides the power to move the train. The alternator
generates AC electricity which is used to provide power for the traction motors mounted on the trucks
(bogies). In older locomotives, the alternator was a DC machine, called a generator. It produced direct
current which was used to provide power for DC traction motors. Many of these machines are still in regular
use.The next development was the replacement ofthe generator by the alternator but still using DC traction
motors. The AC output is rectified to give the DC required for the motors.

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Auxiliary Alternator
Locomotives used to operate passenger trains are equipped with an auxiliary alternator. This provides AC
power for lighting, heating, air conditioning, dining facilities etc. on the train. The
output is transmitted along the train through an auxiliary power line. In the US, it is known as "head end
power" or "hotelpower".In the UK, air conditioned passenger coaches get what is called electric train supply
(ETS) from the auxiliary alternator.
Motor Blower
The diesel engine also drives a motor blower. As its name suggests, the motor blower provides air which is
blown over the traction motors to keep them cool during periods of heavy work. The blower is mounted
inside the locomotive body but the motors are on the trucks, so the blower output is connected to each of
the motors through flexible ducting. The blower output also cools the alternators. Some designs have
separate blowers for the group of motors on each truck and others for the alternators. Whatever the
arrangement,a modern locomotive has a complex air management systemwhich monitors the temperature
of the various rotating machines in the locomotive and adjusts the flow of air accordingly.
Air Intakes
The air for cooling the locomotive's motors is drawn in from outside the locomotive. It has to be filtered to
remove dust and other impurities and its flow regulated by temperature, both inside and outside the
locomotive. The air management system has to take account of the wide range of temperatures from the
possible +40°C of summer to the possible -40°C of winter.
Rectifiers/Inverters
The output from the main alternator is AC but it can be used in a locomotive with either DC or AC traction
motors. DC motors were the traditional type used for many years but, in the last 10 years, AC motors have
become standard for new locomotives. They are cheaper to build and cost less to maintain and, with
electronic management can be very finely controlled.
To convert the AC output from the main alternator to DC, rectifiers are required. If the motors are DC, the
output fromthe rectifiers is used directly.If the motors are AC,the DC output from the rectifiers is converted
to 3-phase AC for the traction motors.
In the US, there are some variations in how the inverters are configured. GM EMD relies on one inverter per
truck, while GE uses one inverter per axle - both systems have their merits. EMD's system links the axles
within each truck in parallel, ensuring wheel slip control is maximised among the axles equally. Parallel
control also means even wheel wear even between axles. However, if one inverter (i.e. one truck) fails then
the unit is only able to produce 50 per cent of its tractive effort. One inverter per axle is more complicated,
but the GE view is that individual axle control can provide the best tractive effort. If an inverter fails, the
tractive effort for that axle is lost, but full tractive effort is still available through the other five inverters. By
controlling each axle individually, keeping wheel diameters closely matched for optimum performance is no
longer necessary.
Electronic Controls
Almost every part of the modern locomotive's equipment has some form of electronic control. These are
usually collected in a control cubicle near the cab for easy access. The controls will usually include a
maintenance management system of some sort which can be used to download data to a portable or hand-
held computer.

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Control Stand
This is the principal man-machine interface, known as a control desk in the UK or control stand in the US.
The common US type of stand is positioned at an angle on the left side of the driving position and, it is said,
is much preferred by drivers to the modern desk type of control layout usual in Europe and now being
offered on some locomotives in the US.
Cab
The standard configuration of US-designed locomotives is to have a cab at one end of the locomotive only.
Since most the US structure gauge is large enough to allow the locomotive to have a walkway on either
side, there is enough visibility for the locomotive to be worked in reverse. However, it is normal for the
locomotive to operate with the cab forwards. In the UK and many European countries, locomotives are full
width to the structure gauge and cabs are therefore provided at both ends.
Batteries
Just like an automobile,the dieselengine needs a battery to start it and to provide electricalpower for lights
and controls when the engine is switched off and the alternator is not running.
Traction Motor
Since the diesel-electric locomotive uses electric transmission, traction motors are provided on the axles to
give the final drive. These motors were traditionally DC but the development of modern power and control
electronics has led to the introduction of 3-phase AC motors. For a description of how this technology work.
There are between four and six motors on most diesel-electric locomotives. A modern AC motor with air
blowing can provide up to 1,000 hp.
Pinion/Gear
The traction motor drives the axle through a reduction gear of a range between 3 to 1 (freight) and 4 to 1
(passenger).
Fuel Tank
A diesel locomotive has to carry its own fuel around with it and there has to be enough for a reasonable
length of trip. The fuel tank is normally under the loco frame and will have a capacity of say 1,000 imperial
gallons (UK Class 59, 3,000 hp) or 5,000 US gallons in a General Electric AC4400CW 4,400 hp locomotive.
The new AC6000s have 5,500 gallon tanks. In addition to fuel, the locomotive will carry around, typically
about 300 US gallons of cooling water and 250 gallons of lubricating oil for the diesel engine.
Air Reservoirs
Air reservoirs containing compressed air at high pressure are required for the train braking and some other
systems on the locomotive.These are often mounted next to the fueltank under the floor of the locomotive.
Air Compressor
The air compressor is required to provide a constant supply of compressed air for the locomotive and train
brakes. In the US, it is standard practice to drive the compressor off the diesel engine drive shaft. In the
UK, the compressor is usually electrically driven and can therefore be mounted anywhere. The Class 60
compressor is under the frame, whereas the Class 37 has the compressors in the nose.

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Drive Shaft
The main output from the diesel engine is transmitted by the drive shaft to the alternators at one end and
the radiator fans and compressor at the other end.
Gear Box
The radiator and its cooling fan is often located in the roof of the locomotive. Drive to the fan is therefore
through a gearbox to change the direction of the drive upwards.
Radiator and Radiator Fan
The radiator works the same way as in an automobile. Water is distributed around the engine block to keep
the temperature within the most efficient range for the engine. The water is cooled by passing it through a
radiator blown by a fan driven by the diesel engine.
Turbo Charging
The amount of power obtained from a cylinder in a diesel engine depends on how much fuel can be burnt
in it. The amount of fuel which can be burnt depends on the amount of air available in the cylinder. So, if
you can get more air into the cylinder, more fuel will be burnt and you will get more power out of your
ignition. Turbo charging is used to increase the amount of air pushed into each cylinder. The turbocharger
is driven by exhaust gas from the engine. This gas drives a fan which, in turn, drives a small compressor
which pushes the additional air into the cylinder. Turbocharging gives a 50% increase in engine power.
The main advantage of the turbocharger is that it gives more power with no increase in fuel costs because
it uses exhaust gas as drive power. It does need additional maintenance, however, so there are some type
of lower power locomotives which are built without it.
Sand Box
Locomotives always carry sand to assist adhesion in bad rail conditions. Sand is not often provided on
multiple unit trains because the adhesion requirements are lower and there are normally more driven axles.
Truck Frame
This is the part (called the bogie) carrying the wheels and traction motors of the locomotive. More
information is available at the Bogie Parts or the Wheels and Bogies on this site.
Wheel
The best page for information on wheels is the Wheels and Bogies on this site.
Mechanical Transmission
A diesel-mechanical locomotive is the simplest type of diesel locomotive. As the name suggests, a
mechanical transmission on a diesel locomotive consists a direct mechanical link between the diesel engine
and the wheels. In the example below, the diesel engine is in the 350-500 hp range and the transmission
is similar to that of an automobile with a four speed gearbox. Most of the parts are similar to the diesel-
electric locomotive but there are some variations in design mentioned below.

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Fluid Coupling
In a diesel-mechanical transmission, the main drive shaft is coupled to the engine by a fluid coupling. This
is a hydraulic clutch, consisting of a case filled with oil, a rotating disc with curved blades driven by the
engine and another connected to the road wheels. As the engine turns the fan, the oil is driven by one disc
towards the other. This turns under the force of the oil and thus turns the drive shaft. Of course, the start
up is gradual until the fan speed is almost matched by the blades. The whole system acts like an automatic
clutch to allow a graduated start for the locomotive.
Gearbox
This does the same job as that on an automobile. It varies the gear ratio between the engine and the road
wheels so that the appropriate level of power can be applied to the wheels. Gear change is manual. There
is no need for a separate clutch because the functions of a clutch are already provided in the fluid coupling.
Final Drive
The diesel-mechanicallocomotive uses a finaldrive similar to that of a steamengine.The wheels are coupled
to each other to provide more adhesion. The output from the 4-speed gearbox is coupled to a final drive
and reversing gearbox which is provided with a transverse drive shaft and balance weights.This is connected
to the driving wheels by connecting rods.
Hydraulic Transmission
Hydraulic transmission works on the same principal as the fluid coupling but it allows a wider range of "slip"
between the engine and wheels. It is known as a "torque converter". When the train speed has increased
sufficiently to match the engine speed, the fluid is drained out of the torque converter so that the engine is
virtually coupled directly to the locomotive wheels. It is virtually direct because the coupling is usually a
fluid coupling, to give some "slip". Higher speed locomotives use two or three torque converters in a
sequence similar to gear changing in a mechanical transmission and some have used a combination of
torque converters and gears.

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Some designs of diesel-hydraulic locomotives had two diesel engines and two transmission systems, one for
each bogie. The design was poplar in Germany (the V200 series of locomotives, for example) in the 1950s
and was imported into parts of the UK in the 1960s. However, it did not work well in heavy or express
locomotive designs and has largely been replaced by diesel-electric transmission.
Wheel Slip
Wheels slip is the bane of the driver trying to get a train away smoothly. The tenuous contact between steel
wheel and steel rail is one of the weakest parts of the railway system. Traditionally, the only cure has been
a combination ofthe skill of the driver and the selective use ofsand to improve the adhesion.Today,modern
electronic control has produced a very effective answer to this age old problem. The system is called creep
control.
Extensive research into wheel slip showed that, even after a wheelset starts to slip, there is still a
considerable amount ofuseable adhesion available for traction.The adhesion is available up to a peak,when
it will rapidly fall away to an uncontrolled spin. Monitoring the early stages of slip can be used to adjust the
power being applied to the wheels so that the adhesion is kept within the limits of the "creep" towards the
peak level before the uncontrolled spin sets in.
The slip is measured by detecting the locomotive speed by Doppler radar (instead ofthe usualmethod using
the rotating wheels) and comparing it to the motor current to see if the wheel rotation matches the ground
speed. If there is a disparity between the two, the motor current is adjusted to keep the slip within the
"creep" range and keep the tractive effort at the maximum level possible under the creep conditions.
Diesel Multiple Units (DMUs)
The diesel engines used in DMUs work on exactly the same principles as those used in locomotives, except
that the transmission is normally mechanical with some form of gear change system. DMU engines are
smaller and several are used on a train, depending on the configuration. The diesel engine is often mounted
under the car floor and on its side because ofthe restricted space available.Vibration being transmitted into
the passenger saloon has always been a problem but some of the newer designs are very good in this
respect.
There are some diesel-electric DMUs around and these normally have a separate engine compartment
containing the engine and the generator or alternator.
The Diesel Engine
The diesel engine was first patented by Dr Rudolf Diesel (1858-1913) in Germany in 1892 and he actually
got a successful engine working by 1897. By 1913, when he died, his engine was in use on locomotives and
he had set up a facility with Sulzer in Switzerland to manufacture them. His death was mysterious in that
he simply disappeared from a ship taking him to London.
The diesel engine is a compression-ignition engine, as opposed to the petrol (or gasoline) engine, which is
a spark-ignition engine. The spark ignition engine uses an electrical spark from a "spark plug" to ignite the
fuel in the engine's cylinders, whereas the fuel in the diesel engine's cylinders is ignited by the heat caused
by air being suddenly compressed in the cylinder. At this stage, the air gets compressed into an area 1/25th
of its original volume. This would be expressed as a

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compression ratio of 25 to 1. A compression ratio of 16 to 1 will give an air pressure of 500 lbs/in² (35.5
bar) and will increase the air temperature to over 800°F (427°C).
The advantage of the diesel engine over the petrol engine is that it has a higher thermal capacity (it gets
more work out of the fuel), the fuel is cheaper because it is less refined than petrol and it can do heavy
work under extended periodsofoverload.It can however,in a high speed form, be sensitive to maintenance
and noisy, which is why it is still not popular for passenger automobiles.
Diesel Engine Types
There are two types of diesel engine, the two-stroke engine and the four-stroke engine. As the names
suggest, they differ in the number of movements of the piston required to complete each cycle of operation.
The simplest is the two-stroke engine. It has no valves. The exhaust from the combustion and the air for
the new stroke is drawn in through openings in the cylinder wall as the piston reaches the bottom of the
downstroke. Compression and combustion occurs on the upstroke. As one might guess, there are twice as
many revolutions for the two-stroke engine as for equivalent power in a four-stroke engine.
The four-stroke engine works as follows: Downstroke 1 - air intake, upstroke 1 - compression, downstroke
2 - power, upstroke 2 - exhaust. Valves are required for air intake and exhaust, usually two for each. In this
respect it is more similar to the modern petrol engine than the 2-stroke design.
In the UK, both types of diesel engine were used but the 4-stroke became the standard. The UK Class 55
"Deltic" (not now in regular main line service) unusually had a two-stroke engine. In the US, the General
Electric (GE) built locomotives have 4-stroke engines whereas General Motors (GM) always used 2-stroke
engines until the introduction of their SD90MAC 6000 hp "H series" engine, which is a 4-stroke design.
The reason for using one type or the other is really a question of preference. However, it can be said that
the 2-stroke design is simpler than the 4-stroke but the 4-stroke engine is more fuel efficient.
Size Does Count
Basically, the more power you need, the bigger the engine has to be. Early diesel engines were less than
100 horse power (hp) but today the US is building 6000 hp locomotives. For a UK locomotive of 3,300 hp
(Class 58), each cylinder will produce about 200 hp, and a modern engine can double this if the engine is
turbocharged.
The maximum rotational speed of the engine when producing full power will be about 1000 rpm (revolutions
per minute) and the engine will idle at about 400 rpm. These relatively low speeds mean that the engine
design is heavy, as opposed to a high speed, lightweight engine. However, the UK HST (High Speed Train,
developed in the 1970s) engine has a speed of 1,500 rpm and this is regarded as high speed in the railway
diesel engine category. The slow, heavy engine used in railway locomotives will give low maintenance
requirements and an extended life.
There is a limit to the size of the engine which can be accommodated within the railway loading gauge, so
the power of a single locomotive is limited. Where additional power is required, it has become usual to add
locomotives. In the US, where freight trains run into tens of thousands of

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tons weight, four locomotives at the head of a train are common and several additional ones in the middle
or at the end are not unusual.
To V or not to V
Diesel engines can be designed with the cylinders "in-line", "double banked" or in a "V". The double banked
engine has two rows of cylinders in line. Most diesel locomotives now have V form engines. This means that
the cylinders are split into two sets, with half forming one side of the V. A V8 engine has 4 cylinders set at
an angle forming one side ofthe V with the other set offour forming the other side.The crankshaft,providing
the drive, is at the base of the V. The V12 was a popular design used in the UK. In the US, V16 is usual for
freight locomotives and there are some designs with V20 engines.
Engines used for DMU (diesel multiple unit) trains in the UK are often mounted under the floor of the
passenger cars. This restricts the design to in-line engines, which have to be mounted on their side to fit in
the restricted space.
An unusual engine design was the UK 3,300 hp Class 55 locomotive, which had the cylinders arranged in
three sets of opposed Vs in an triangle, in the form of an upturned delta, hence the name "Deltic".
Tractive Effort, Pull and Power
Before going too much further, we need to understand the definitions of tractive effort, drawbar pull and
power. The definition of tractive effort (TE) is simply the force exerted at the wheel rim of the locomotive
and is usually expressed in pounds (lbs) or kilo Newtons (kN). By the time the tractive effort is transmitted
to the coupling between the locomotive and the train, the drawbar pull, as it is called will have reduced
because of the friction of the mechanical parts of the drive and some wind resistance.
Power is expressed as horsepower (hp) or kilo Watts (kW) and is actually a rate of doing work. A unit of
horsepower is defined as the work involved by a horse lifting 33,000 lbs one foot in one minute. In the
metric system it is calculated as the power (Watts) needed w hen one Newton of force is moved one metre
in one second. The formula is P = (F*d)/t where P is power, F is force, d is distance and t is time. One
horsepower equals 746 Watts.
The relationship between power and drawbar pull is that a low speed and a high drawbar pull can produce
the same power as high speed and low drawbar pull. If you need to increase higher tractive effort and high
speed, you need to increase the power. To get the variations needed by a locomotive to operate on the
railway, you need to have a suitable means of transmission between the diesel engine and the wheels.
One thing worth remembering is that the power produced by the dieselengine is not allavailable for traction.
In a 2,580 hp diesel electric locomotive, some 450 hp is lost to on-board equipment like blowers, radiator
fans, air compressors and "hotel power" for the train.
Starting
A diesel engine is started (like an automobile) by turning over the crankshaft until the cylinders "fire" or
begin combustion. The starting can be done electrically or pneumatically. Pneumatic starting was used for
some engines. Compressed air was pumped into the cylinders of the engine

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until it gained sufficient speed to allow ignition, then fuel was applied to fire the engine. The compressed air
was supplied by a small auxiliary engine or by high pressure air cylinders carried by the locomotive.
Electric starting is now standard. It works the same way as for an automobile, with batteries providing the
power to turn a starter motor which turns over the main engine. In older locomotives fitted with DC
generators instead of AC alternators, the generator was used as a starter motor by applying battery power
to it.
Governor
Once a diesel engine is running, the engine speed is monitored and controlled through a governor. The
governor ensures that the engine speed stays high enough to idle at the right speed and that the engine
speed will not rise too high when full power is demanded. The governor is a simple mechanical device which
first appeared on steam engines. It operates on a diesel engine as below.
The governor consists ofa rotating shaft,which is driven by the dieselengine.A pair of flyweights are linked
to the shaft and they rotate as it rotates. The centrifugal force caused by the rotation causes the weights to
be thrown outwards as the speed of the shaft rises. If the speed falls the weights move inwards.
The flyweights are linked to a collar fitted around the shaft by a pair of arms. As the weights move out, so
the collar rises on the shaft. If the weights move inwards, the collar moves down the shaft. The movement
of the collar is used to operate the fuel rack lever controlling the amount of fuel supplied to the engine by
the injectors.
Fuel Injection
Ignition is a diesel engine is achieved by compressing air inside a cylinder until it gets very hot (say 400°C,
almost 800°F) and then injecting a fine spray of fuel oil to cause a miniature explosion. The explosion forces
down the piston in the cylinder and this turns the crankshaft. To get the fine spray needed for successful
ignition the fuel has to be pumped into the cylinder at high pressure. The fuel pump is operated by a cam
driven off the engine. The fuel is pumped into an injector, which gives the fine spray of fuel required in the
cylinder for combustion.

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Fuel Control
In an automobile engine, the power is controlled by the
amount offuel/air mixture applied to the cylinder.The mixture is mixed outside the cylinder and then applied
by a throttle valve. In a diesel engine the amount of air applied to the cylinder is constant so power is
regulated by varying the fuel input. The fine spray of fuel injected into each cylinder has to be regulated to
achieve the amount of power required. Regulation is achieved by varying the fuel sent by the fuel pumps to
the injectors. The control arrangement is shown in the diagram left.
The amount offuel being applied to the cylinders is varied by altering the effective delivery rate of the piston
in the injector pumps. Each injector has its own pump, operated by an engine-driven cam, and the pumps
are aligned in a row so that they can all be adjusted together. The adjustment is done by a toothed rack
(called the "fuel rack") acting on a toothed section of the pump mechanism. As the fuel rack moves, so the
toothed section of the pump rotates and provides a drive to move the pump piston round inside the pump.
Moving the piston round, alters the size of the channel available inside the pump for fuel to pass through to
the injector delivery pipe.
The fuel rack can be moved either by the driver operating the power controller in the cab or by the governor.
If the driver asks for more power, the control rod moves the fuel rack to set the pump pistons to allow more
fuel to the injectors. The engine will increase power and the governor will monitor engine speed to ensure
it does not go above the predetermined limit. The limits are fixed by springs (not shown) limiting the weight
movement.
Engine Control Development
So far we have seen a simple example of diesel engine control but the systems used by most locomotives
in service today are more sophisticated. To begin with, the drivers control was combined with the governor
and hydraulic control was introduced. One type of governor uses oil to control the fuel racks hydraulically
and another uses the fuel oil pumped by a gear pump driven by the engine. Some governors are also linked
to the turbo charging system to ensure that fuel does not increase before enough turbocharged air is
available. In the most modern systems, the governor is electronic and is part of a complete engine
management system.

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Power Control
The diesel engine in a diesel-electric locomotive provides the drive for the main alternator which, in turn,
provides the power required for the traction motors.We can see fromthis therefore,that the power required
from the diesel engine is related to the power required by the motors. So, if we want more power from the
motors, we must get more current from the alternator so the engine needs to run faster to generate it.
Therefore, to get the optimum performance from the locomotive, we must link the control of the diesel
engine to the power demands being made on the alternator.
In the days of generators, a complex electro-mechanical system was developed to achieve the feedback
required to regulate engine speed according to generator demand. The core of the system was a load
regulator, basically a variable resistor which was used to very the excitation of the generator so that its
output matched engine speed. The control sequence (simplified) was as follows:
1. Driver moves the power controller to the full power position
2. An air operated piston actuate d by the controller moves a lever, which closes a switch to supply
a low voltage to the load regulator motor.
3. The load regulator motor moves the variable resistor to increase the main generator field
strength and therefore its output.
4. The load on the engine increases so its speed falls and the governor detects the reduce d speed.
5. The governor weights drop and cause the fuel rack servo system to actuate.
6. The fuel rack moves to increase the fuel supplied to the injectors and therefore the power from
the engine.
7. The lever (mentioned in 2 above) is used to reduce the pressure of the governor spring.
8. When the engine has responded to the new control and governor settings, it and the generator will be
producing more power.
On locomotives with an alternator, the load regulation is done electronically. Engine speed is measured like
modern speedometers, by counting the frequency of the gear teeth driven by the engine, in this case, the
starter motor gearwheel. Electrical control of the fuel injection is another improvement now adopted for
modern engines. Overheating can be controlled by electronic monitoring of coolant temperature and
regulating the engine power accordingly. Oil pressure can be monitored and used to regulate the engine
power in a similar way.
Cooling
Like an automobile engine, the diesel engine needs to work at an optimum temperature for best efficiency.
When it starts, it is too cold and, when working, it must not be allowed to get too hot. To keep the
temperature stable, a cooling system is provided. This consists of a water-based coolant circulating around
the engine block, the coolant being kept cool by passing it through a radiator.
The coolant is pumped round the cylinder block and the radiator by an electrically or belt driven pump. The
temperature is monitored by a thermostat and this regulates the speed of the (electric or hydraulic) radiator
fan motor to adjust the cooling rate. When starting the coolant isn't circulated at all. After all, you want the
temperature to rise as fast as possible when starting on a cold morning and this will not happen if you a
blowing cold air into your radiator. Some radiators are provided with shutters to help regulate the
temperature in cold conditions.
If the fan is driven by a belt or mechanicallink, it is driven through a fluid coupling to ensure that no damage
is caused by sudden changes in engine speed. The fan works the same way as in an automobile, the air
blown by the fan being used to cool the water in the radiator. Some engines have fans with an electrically
or hydrostatically driven motor. An hydraulic motor uses oil under pressure which has to be contained in a

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special reservoir and pumped to the motor. It has the advantage of providing an in-built fluid coupling.
A problem with engine cooling is cold weather. Water freezes at 0°C or 32°F and frozen cooling water will
quickly split a pipe or engine block due to the expansion of the water as it freezes. Some systems are "self
draining" when the engine is stopped and most in Europe are designed to use a mixture of anti-freeze, with
Gycol and some form of rust inhibitor. In the US, engines do not normally contain anti-freeze, although the
new GM EMD "H" engines are designed to use it. Problems with leaks and seals and the expense of putting
a 100 gallons (378.5 litres)ofcoolant into a 3,000 hp engine,means that enginesin the UShave traditionally
operated without it. In cold weather, the engine is left running or the locomotive is kept warm by putting it
into a heated building or by plugging in a shore supply. Another reason for keeping diesel engines running
is that the constant heating and cooling caused by shutdowns and restarts, causes stresses in the block and
pipes and tends to produce leaks.
Lubrication
Like an automobile engine,a dieselengine needslubrication.In an arrangement similar to the engine cooling
system, lubricating oil is distributed around the engine to the cylinders, crankshaft and other moving parts.
There is a reservoir of oil, usually carried in the sump, which has to be kept topped up, and a pump to keep
the oil circulating evenly around the engine. The oil gets heated by its passage around the engine and has
to be kept cool, so it is passed through a radiator during its journey. The radiator is sometimes designed as
a heat exchanger, where the oil passes through pipes encased in a water tank which is connected to the
engine cooling system.
The oil has to be filtered to remove impurities and it has to be monitored for low pressure. If oil pressure
falls to a level which could cause the engine to seize up, a "low oil pressure switch" will shut down the
engine. There is also a high pressure relief valve, to drain off excess oil back to the sump.
Transmissions
Like an automobile, a diesel locomotive cannot start itself directly from a stand. It will not develop
maximum power at idling speed, so it needs some form of transmission system to multiply torque
when starting. It will also be necessary to vary the power applied according to the train weight or the
line gradient. There are three methods of doing this: mechanical, hydraulic or electric. Most diesel
locomotives use electric transmission and are called "diesel-electric" locomotives. Mechanical and
hydraulic transmissions are still used but are more common on multiple unit trains or lighter
locomotives.

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Chapter 2
2.1 What Makes A Diesel Locomotive Work?
The ignition of diesel fuel pushes pistons connected to an electric generator. The resulting electricity
powers motors connected to the wheels of the locomotive. A “diesel” internal combustion engine
uses the heat generated from the compression of air during the upward cycles of the stroke to ignite
the fuel. The inventor Dr. Rudolph Diesel designed this type of engine. It was patented in 1892.
Diesel fuel is stored in a fuel tank and delivered to the engine by an electric fuel pump. Diesel fuel
has become the preferred fuel for railroad locomotive use due to its lower volatility, lower cost, and
common availability.
The diesel engine (A) is the main component of the diesel-electric locomotive. It is an internal
combustion engine comprised of several cylinders connected to a common crankshaft. Fuel is ignited
by the intense compression, pushing the piston down. The piston’s movement turns a crankshaft.
The diesel engine is connected to the main generator (B), which converts the engine’s mechanical
power to electrical power. The electricity is then distributed to traction motors (C) through circuits
established by various switchgear components.
Because it is always turning, whether the locomotive is moving or not, the main generator’s output is
controlled by the excitation field current to its windings.
The engineer controls the power output of the locomotive by using an electrically-controlled throttle.
As it is opened, more fuel is injected into the engine’s cylinders, increasing its mechanical power
output. Main generator excitation increases, increasing its electrical output.
Each traction motor (C) is directly geared to a pair of driving wheels. The use of using a mechanical
transmission and clutch. Starting a heavy train from a dead stop would burn out a clutch in a brief
time.

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The ignition of diesel fuel pushes pistons connected to an electric generator. The resulting electricity
powers motors connected to the wheels of the locomotive. A “diesel” internal combustion engine
uses the heat generated from the compression of air during the upward cycles of the stroke to ignite
the fuel. The inventor Dr. Rudolph Diesel designed this type of engine. It was patented in 1892.
1. Diesel fuel is stored in a fuel tank and delivered to the engine by an electric fuel pump. Diesel
fuel has become the preferred fuel for railroad locomotive use due to its lower volatility, lower
cost, and common availability.
2. The diesel engine (A) is the main component of the diesel-electric locomotive. It is an internal
combustion engine comprised of several cylinders connected to a common crankshaft. Fuel is
ignited by the intense compression, pushing the piston down. The piston’s movement turns a
crankshaft.
3. The diesel engine is connected to the main generator (B), which converts the engine’s
mechanical power to electrical power. The electricity is then distributed to traction
motorsstablished by various switchgear components.
4. Because it is always turning, whether the locomotive is moving or not, the main generator’s
output is controlled by the excitation field current to its windings.
5. The engineer controls the power output of the locomotive by using an electrically-controlled
throttle. As it is opened, more fuel is injected into the engine’s cylinders, increasing its
mechanical power output. Main generator excitation increases, increasing its electrical output.
6. Each traction motor (C) is directly geared to a pair of driving wheels. The use of electriclutch.
Starting a heavy train from a dead stop would burn out a clutch in a brief time.

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Chapter 3
MAGNETIC SERVICE SHOP (MSS)
3.1 Variable Frequency Drive (VFD)
It is interesting to know that the first A.C. drive (400 HP) based on thyratron cycloconverter-fed
WRIM was installed in 1932 by F.E. Alexanderson of General Electric in the Logan Power Station
of Pacific Gas and Electric Company. From then industrial drives have evolved rapidly by dedicated
effort of many scientists and engineers all over the world resulting in development of advanced drive
technology such as Variable Frequency Drive (VFD).
VFD is a power electronics based device which converts a basic fixed frequency, fixed voltage sine
wave power (line power) to a variable frequency, variable output voltage used to control speed of
induction motor(s). It regulates the speed of a three phase induction motor by controlling the
frequency and voltage of the power supplied to the motor.
Since the number of pole is constant the speed Ns can
be varied by continuously changing frequency.
Fig 3.1 VFD

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3.1.1 Working of Variable Frequency Drive
Any Variable Frequency Drive or VFD incorporates following three stages for controlling
a three phase induction motor.
 Rectifier Stage
A full-wave power diode based solid-state rectifier converts three-phase 50 Hz power from a
standard 220, 440 or higher utility supply to either fixed or adjustable DC voltage. The system may
include transformers for high voltage system.
 Inverter Stage
Power electronic switches such as IGBT, GTO or SCR switch the DC power from rectifier on and
off to produce a current or voltage waveform at the required new frequency. Presently most of the
voltage source inverters (VSI) use pulse width modulation (PWM) because the current and voltage
waveform at output in this scheme is approximately a sine wave. Power Electronic switches such
as IGBT; GTO etc. switch DC voltage at high speed, producing a series of short-width pulses of
constant amplitude. Output voltage is varied by varying the gain of the inverter. Output frequency
is adjusted by changing the number of pulses per half cycle or by varying the period for each time
cycle.
The resulting current in an induction motor simulates a sine wave of the desired output frequency.
The high speed switching action of a PWM inverter results in less waveform distortion and hence
decreases harmonic losses.
 Control System
Its function is to control output voltage i.e. voltage vector of inverter being fed to motor and
maintain a constant ratio of voltage to frequency (V/Hz). It consists of an electronic circuit which
receives feedback information from the driven motor and adjusts the output voltage or frequency
to the desired values. Control system may be based on SPWM (Sine Wave PWM), SVPWM (Space
Vector modulated PWM) or some soft computing based algorithm.
 Induction Motor Characteristic under Variable Frequency Drive

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In an induction motor induced in stator, E is proportional to the product of the slip frequency
and the air gap flux. The terminal voltage can be considered proportional to the product of the
slip frequency and flux, if stator drop is neglected. Any reduction in the supply frequency
without a change in the terminal voltage causes an increase in the air gap flux which will cause
magnetic saturation of motor. Also the torque capability of motor is decreased. Hence while
controlling a motor with the help of VFD or Variable
Frequency Drive we always keep the V/f ratio constant. Now define variable ‘K’ as, For
operation below K < 1 i.e. below rated frequency we have constant flux operation. For this we
maintain constant magnetization current Im for all operating points. For K > 1 i.e. above rated
frequency we maintain terminal voltage V rated constant. In this field is weakened in the
inverse ratio of per unit frequency ‘K’. For values
of K = 1 we have constant torque operation and above that we have constant power
application.
3.1.2 Merits of using Variable Frequency Drives
 Energy Saving
Primary function of VFD in industry is to provide smooth control along with energy
savings. The variable speed motor drive system is more efficient than all other flow
control methods including valves, turbines, hydraulic transmissions, dampers, etc.
Energy cost savings becomes more pronounced in variable-torque ID fan and pump
applications, where the load’s torque and power is directly proportional to the square
and cube of the speed respectively.
 Increased Reliability
Adjustable speed motor-drive systems are more reliable than traditional mechanical
approaches such as using valves, gears, louvers or turbines to control speed and flow.
Unlike mechanical control system they don’t have any moving parts hence they are
highly reliable.
 Speed Variations
Beyond energy saving, applications such as crushers, conveyors and grinding mills can
use the motor and VFD’s packages to provide optimal speed variations. In some crucial
applications, the operating speed range can be wide, which a motor supplied with a
constant frequency power source cannot provide. In the case of conveyors and mills, a

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VFD and motor system can even provide a “crawl” speed foe maintenance purposes
eliminating the need for additional drives.
 Soft Starting
When Variable Frequency Drives start large motors, the drawbacks associated with large inrush
current i.e. starting current (winding stress, winding overheating and voltage dip on connected bus) is
eliminated. This reduces chances of insulation or winding damage and provides extended motor life.
 Extended Machine Life and Less Maintenance
The VFD’s greatly reduce wear to the motor, increase life of the equipment and decrease
maintenance costs. Due to optimal voltage and frequency control it offers better protection to the
motor from issues such as electro thermal overloads, phase faults, over voltage, under voltage etc.
When we start a motor (on load) with help of a VFD, the motor is not subjected to “instant shock”
hence there is less wear and tear of belt, gear and pulley system.
 High Power Factor
Power converted to rotation, heat, sound, etc. is called active power and is measured in kilowatts
(kW). Power that charges builds magnetic fields or charges capacitor is called reactive power and
is measured in kVAR. The vector sum of the kW and the kVAR is the Apparent Power and is
measured in KVA. Power factor is the ratio of kW/KVA. Typical AC motors may have a full
load power factor ranging from 0.7 to 0.8. As the motor load is reduced, the power factor
becomes low. The advantage of using VFD’s is that it includes capacitors in the DC Bus itself
which maintains high power factor on the line side of the Variable Frequency Drive. This
eliminates the need of additional expensive capacitor banks.
 Slip Power Recovery
The fundamental power given to rotor by stator is called air gap power Pg. The mechanical
power developed is given by The term 'sP' is called slip
.

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If the slip is very large i.e. speed is low then there is ample waste of power, a common example
is kiln drives of cement industry. This power can be saved through slip recovery scheme. In this
scheme slip power is first collected through brushes of WRIM. This slip power recovered is then
rectified and inverted back to line frequency and is injected into supply through coupling
transformer. The scheme is shown in figure below.
3.1.3 Applications of Variable Frequency Drive
1. They are mostly used in industries for large induction motor (dealing with variable load) whose
power rating ranges from few kW to few MW.
2. Variable Frequency Drive is used in traction system. In India it is being used by Delhi Metro
Rail Corporation.
3. They are also used in modern lifts, escalators and pumping systems.
4. Nowadays they are being also used in energy efficient refrigerators, AC’s and Outside-air
Economizers.
3.2 About PCB and SMT
3.2.1 What is a Printed Circuit Board?
Printed circuit boards (PCBs) are the boards that are used as the base in most electronics – both as a
physical support piece and as the wiring area for the surface-mounted and socketed components. PCBs
are most commonly made out of fiberglass, composite epoxy, or another composite material.
Most PCBs for simple electronics are simple and composed of only a single layer. More sophisticated
hardware such as computer graphics cards or motherboards can have multiple layers, sometimes up to
twelve.
Although PCBs are most often associated with computers, they can be found in many other electronic
devices, such as TVs, Radios, Digital cameras and Cell phones. In addition to their use in consumer
electronics and computers, different types of PCBs are used in a variety of other fields, including:
• Medical devices. Electronics products are now denser and consume less power than previous
generations, making it possible to test new and exciting medical technology. Most medical devices use
a high-density PCB, which is used to create the smallest and densest design possible. This helps to
alleviate some of the unique constraints involved with developing devices for the medical field due to
the necessity of small size and light weight. PCBs have found their way into everything from small
devices, such as pacemakers, to much larger devices like X-ray equipment or CAT scan machines.
• Industrial machinery. PCBs are commonly used in high-powered industrial machinery. In places
where current one-ounce copper PCBs do not fit the requirements, thick copper PCBs can be utilized
instead. Examples of situations where thicker copper PCBs would be beneficial include motor
controllers, high-current battery chargers and industrial load testers.
• Lighting. As LED-based lighting solutions catch on in popularity because of their low power
consumption and high levels of efficiency, so too do aluminum-backed PCBs which are used to make
them. These PCBs serve as heat sinks and allow for higher levels of heat transfer than a standard PCB.
These same aluminum-backed PCBs form the basis for both high-lumen LED applications and basic
lighting solutions.

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• Automotive and aerospace industries. Both the automotive and aerospace industries make use of
flexible PCBs, which are designed to withstand the high-vibration environments that are common in
both fields. Depending on specifications and design, they can also be very lightweight, which is a
necessity when manufacturing parts for transportation industries. They are also able to conform to the
tight spaces that might be present in these applications, such as inside instrument panels or behind the
instrument gauge on a dashboard.
There are several overall types of PCB boards each with their own particular manufacturing
specifications, material types and usages: Single-layer PCBs, Double-layer PCBs, Multi-layer PCBs,
Rigid PCBs, Flexible PCBs, Rigid-Flex PCBs, High-frequency PCBs, Aluminum-backed PCBs.
 Single-layer PCBs
A single-layer or single-sided PCB is one that is made out of a single layer of base material or
substrate. One side of the base material is coated with a thin layer of metal. Copper is the most
common coating due to how well it functions as an electrical conductor. Once the copper base
plating is applied, a protective solder mask is usually applied, followed by the last silk-screen to
mark out all of the elements on the board.
Since single-layer/single-sided PCBs only have their various circuits and components soldered
onto one side, they are easy to design and manufacture. This popularity means that they can be
purchased at a low-cost, especially for high-volume orders. The low-cost, high volume model
means they are commonly used for a variety of applications, including calculators, cameras,
radio and stereo equipment, solid state drives, printers and power supplies.

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 Double-layer PCBs
Double-layer or double-sided PCBs have a base material with a thin layer of conductive
metal, like copper, applied to both sides of the board. Holes drilled through the board allow
circuits on one side of the board to connect to circuits on the other.
Benefits of Double Sided PCBs:
 More flexibility for designers
 Increased circuit density
 Relatively lower costs
 Intermediate level of circuit complexity
 Reduced board size (which can reduce costs)
Applications of Double Sided PCBs
There are near limitless applications for old and new designs. Fine line surface mount, ultra high
copper build, high and low temperature, Solder coated, Silver, and Gold finishes are just a few
examples of DSPT applications.
The following are applications in which Double Sided PCBs can be used:
 Industrial controls
 Power supplies
 Converters
 Control relays
 Instrumentation
 Regulators

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 UPS systems
 Power conversion
3.2.2 What is SMT (Surface Mount Technology )and why?
Surface-mount technology (SMT) is a method for producing electronic circuits in which the
components are mounted or placed directly onto the surface of printed circuit boards (PCBs). An
electronic device so made is called a surface-mount device (SMD). In the industry it has largely
replaced the through-hole technology construction method of fitting components with wire leads
into holes in the circuit board.Both technologies can be used on the same board for components
not suited to surface mounting such as large transformers and heat-sinked power semiconductors.
An SMT component is usually smaller than its through-hole counterpart because it has either
smaller leads or no leads at all. It may have short pins or leads of various styles, flat contacts, a
matrix of solder balls (BGAs), or terminations on the body of the component.
 What are SMT components?
Surface mount devices, SMDs by their nature are very different to the traditional leaded
components. They can be split into a number of categories:
 Passive SMDs: There is quite a variety of different packages used for passive SMDs.
However the majority of passive SMDs are either resistors or capacitors for which the
package sizes are reasonably well standardised. Other components including coils, crystals
and others tend to have more individual requirements and hence their own packages.
Resistors and capacitors have a variety of package sizes. These have designations that
include: 1812, 1206, 0805, 0603, 0402, and 0201. The figures refer to the dimensions in
hundreds of an inch. In other words the 1206 measures 12 hundreds by 6 hundreds of an
inch. The larger sizes such as 1812 and 1206 were some of the first that were used. They
are not in widespread use now as much smaller components are generally required.
However they may find use in applications where larger power levels are needed or where
other considerations require the larger size.
The connections to the printed circuit board are made through metallised areas at either end
of the package.

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 Transistors and diodes: These components are often contained in a small plastic package.
The connections are made via leads which emanate from the package and are bent so that
they touch the board. Three leads are always used for these packages. In this way it is easy
to identify which way round the device must go.
 Integrated circuits: There is a variety of packages which are used for integrated circuits.
The package used depends upon the level of interconnectivity required. Many chips like
the simple logic chips may only require 14 or 16 pins, whereas other like the VLSI
processors and associated chips can require up to 200 or more. In view of the wide variation
of requirements there is a number of different packages available.
For the smaller chips, packages such as the SOIC (Small Outline Integrated Circuit) may
be used. These are effectively the SMT version of the familiar DIL (Dual In Line) packages
used for the familiar 74 series logic chips. Additionally there are smaller versions including
TSOP (Thin Small OutlinePackage) and SSOP(ShrinkSmallOutlinePackage).
Other packages are also available. One known as a BGA (Ball Grid Array) is used in many
applications. Instead of having the connections on the side of the package, they are
underneath. The connection pads have balls of solder that melt during the soldering process,
thereby making a good connection with the board and mechanically attaching it. As the
whole of the underside of the package can be used, the pitch of the connections is wider
and it is found to be much more reliable.
A smaller version of the BGA, known as the microBGA is also being used for some ICs.
As the name suggests it is a smaller version of the BGA.
 SMT in use
SMT is used almost exclusively for the manufacture of electronic circuit boards these days. They
are smaller, often offer a better level of performance and they can be used with automated pick and
place machine that in many cases all bit eliminate the need for manual intervention in the assembly
process.
Wired components were always difficult to place automatically because the wires needed to be
pre-formed to fit the relevant hole spacing, and even then they were prone to problems with
placement.
Although many connectors and some other components still require assisted placement, printed
circuit boards are normally developed to reduce this to an absolute minimum, even to the extent of
altering the design to use components that can be placed automatically. In addition to this,
component manufacturers have developed some specialised surface mount versions of components
that enable virtually complete automated assembly for most boards.
3.3 About AC and Work
An air conditioner (AC) in a room or a car works by collecting hot air from a given space,
processing it within itself with the help of a refrigerant and a bunch of coils and then releasing cool
air into the same space where the hot air had originally been collected. This is essentially how air
conditioners work.
 Parts of an air conditioner
Air conditioner installations mainly come in two types: window systems and split systems (these
are further classified into mini-split and central systems). In everyday language, these are
commonly referred to as window ACs and split ACs, respectively.

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Regardless of the type of installation, all air conditioners consist of four major components that are
listed below:
 Evaporator
An evaporator is basically a heat exchanger coil that’s responsible for collecting heat
from inside a room through a refrigerant gas. This component is known as the evaporator,
and is where the liquid refrigerant absorbs heat and evaporates to become gas.
Some of the most common refrigerant gases used in air conditioning systems include
hydrofluorocarbons or HFCs (like, R-410A) hydrochlorofluorocarbons or HCFCs (like,
R-22) and hydrocarbons (like R-290 and R-600A). It is this gas that actually absorbs the
heat from the room and travels to the the next component for further processing, which
is…
 Compressor
As the name clearly signifies, this is where compression of the gaseous refrigerant
occurs. It’s located in the outside unit, i.e., the part that’s installed outside the house.
 Condenser
The condenser receives the vaporized refrigerant from the compressor, converts it back
to liquid and expels the heat outside. Needless to say, it’s also located on the outside unit
of the split AC.
 Expansion valve
Also referred to as the throttling device, the expansion valve is located between the two
sets of coils (the chilled coils of the evaporator and the hot coils of the condenser). It
keeps tabs on the amount of refrigerant moving towards the evaporator.
Note that in the case of window ACs, the three aforementioned components are all
located inside a small metal box that is installed in a window opening.
These are the main components of an air conditioner. Now let’s look at how they work
together to make an AC do what it does.
 Air conditioner (AC) working principle
An air conditioner collects hot air from a given space, processes it within itself with the help
of a refrigerant and a bunch of coils and then releases cool air into the same space where the hot
air had originally been collected. This is essentially how all air conditioners work.
Many folks believe that an air conditioner produces chilled air with the help of machines
installed inside it, allowing it to cool a room so quickly. That might also explain why it
consumes so much electricity. In reality, however, that’s a misconception. An air conditioner
is not a magical device; it just uses some physical and chemical phenomena very effectively to
cool a given space.

35
When you switch an AC on and set your desired temperature (say, 20 degrees Celsius), the
thermostat installed in it senses that there is a difference in the temperature of the room’s air
and the temperature that you’ve chosen.This warm air is drawn in through a grille at the base
of the indoor unit, which then flows over some pipes through which the refrigerant (i.e., a
coolant fluid) is flowing. The refrigerant liquid absorbs the heat and becomes a hot gas itself.
This is how heat is removed from the air that falls on the evaporator coils. Note that the
evaporator coil not only absorbs heat, but also wrings out moisture from the incoming air,
which helps to dehumidify the room.This hot refrigerant gas is then passed on to the
compressor (located on the outside unit). Being true to its name, the compressor compresses
the gas so that it becomes hot, since compressing a gas increases its temperature.This hot, high-
pressure gas then travels to the third component – the condenser. Again, the condenser remains
true to its name, and condenses the hot gas so that it becomes a liquid.The refrigerant reaches
the condenser as a hot gas, but quickly becomes a cooler liquid because the heat of the ‘hot
gas’ is dissipated to the surroundings through metal fins. So, as the refrigerant leaves the
condenser, it loses its heat and becomes a cooler liquid. This flows through an expansion valve
– a tiny hole in the system’s copper tubing – which controls the flow of cool liquid refrigerant
into the evaporator, so the refrigerant arrives at the point where its journey started.Here’s a
simplified diagram of the air-conditioning process:
3.4 About 5502A Multi-Product Calibrator
 5502A features at a glance
• Calibrates a wide variety of electrical test equipment
• Robust protection circuits prevent costly damage from operator error
• Ergonomically designed carrying handles make the 5502A easy to transport
• Rugged carrying case with built-in handles and wheels and removable front/rear access doors
for in-situ calibration in almost any environment

36
• Current output that extends to 120 A when paired with the 52120A Transconductance
Amplifier
• Remarkably affordable
 Practical solutions for calibrating in the lab or in the field
Robust, transportable solution to match your workload and budget
 Calibrates a wide variety of electrical test equipment
 Robust protection circuits prevent costly damage from operator error
 Ergonomically designed carrying handles make the 5502A easy to transport
 Rugged carrying case with built-in handles and wheels and removable front/rear access doors for
in-situ calibration in almost any environment
 Current output that extends to 120 A when paired with the 52120A Transconductance Amplifier
 Remarkably affordable
The 5502A calibrator covers many of the most common items in your workload,
including:
 Handheld and bench meters (analog and digital) to 4.5 digits
 Current clamps and clamp meters
 Panel meters
 Electronic thermometers
 Chart recorders
 Oscilloscope recorders
 XY recorders
 Data loggers

37
 Summary specifications:
Fig:
5502A Multi-Product Calibrator with multimeter
Function and range
Direct volts 0 to ± 1020 V
Direct current 0 to ± 20.5 A
Alternating volts 1 mV to 1020 V
10 Hz to 500 kHz
Volt/hertz 1000 V@10 kHz/330 V@100 kHz
Alternating current 29 µA to 20.5 A
10 Hz to 30 kHz
Waveforms Sine, square, triangle, truncated sine
Resistance 0 Ωto 1100 MΩ
Capacitance 220 pF to 110 mF
Power (phantom loads) 20.9 kW
Phase control 0.01°
Thermocouple (source
and measure
temperature)
B, C,E, J, K L N R, S, T,
U 10 µV/°C and 1
mV/°CRTD (source temperature) Pt 385-100 Ω, Pt 3926-100 ΩPt 3916-100 Ω, Pt
385-200 Ω, Pt 385-500 Ω, Pt 385 1000 Ω, PtNi
385-120 Ω (Ni120), Cu 427 10 Ω
Interfaces RS-232, IEEE 488
Frequency uncertainty < 25 ppm
Oscilloscope calibrator
(options)
Levelled sine wave from 5 mV to 5.5 Vpp max,
frequencies 50 kHz to 600 kHz; edge rise times
of < 300 ps, multiple trig- ger functions, lowest dc,
square wave and timing uncertaintyAmplified current
(accessory
amplifier)
Extend from 20.5 A to a maximum of 100 A dc and
120 A ac from 10 Hz to 10 k Hz

38
Chapter 4
Loco Test Shop (LTS)
It is the shop where the final testing of the engine is performed before the engine is dispatched
for use by the Indian railways.
The important electrical inspections and tests performed are:
FIR
Impulse
Insulation Registering (IR)
High Potential Test
Battery Connection
Digital I/O checking (for microprocessor control unit)
Fuel pressure adjustment
Engine Cranking
Auxiliary Generator Check
AC Voltage Check
Temperature switch check
Load cable connection and load test
Loco Normalisation test (In which load cable is disconnected)
Traction Motor boot application
DM Boot application
Track test and dynamic brake checking
Running operation
Brake safety devices
Static air pressure (SAP) test for motor cooling
Rotary machine inspection
Locomotive Brake Systems
a) Charging
b) Pressure gauges
c) Compressor governor
d) Main Reservoir Leakage
e) Reservoir Check Valve
f) Brake Pipe Leakage
g) Air Compressor Check
h) Auto brake valve
i) Brake Pipe Maintaining Feature
j) Independent Brake
k) Cut off Valve
l) Lead or Trail Selector
m) Dynamic Interlock
n) Brake Cylinder Leakage

39
o) Brake-in-two
p) Main Reservoir Safety Valve
q) Vigilance Control
r) Remote Control Locomotive
4.1 AN OUTLINE OF LOCO TESTING
Electric locomotives must be tested at normal line voltage. A general outline of loco testing is as
mentioned below. However, it’s a mere picture of what’s actually done. The actual no. of tests is very
large and it was out of the scope of the training.
1. Engine is brought to the shop LTS
2. It’s inspected properly for any visible locomotive errors.
3. Fuel Oil tank is tested for leakage.
4. This is done by filling it with water.
5. Indon solution (0.68 kg in 1000L of water) is filled in expansion tank
6. Lube oil filling
7. Air compressor/expresser setting is tested
8. Crank shaft delection and lube oil circulation tests are performed.
9. Initial working and temperature checking is done:
Lube oil pressure: 4-5 kg/cm²
Fuel oil pressure: 3.5-4.5 kg/cm²
10. Load Test:
All load connections are made
Crank case vacuum is checked
U tube water manometer is used to measure the pressure of fuel oil. At full
load,
a) Lube oil pressure: 6.5-7.5 kg/cm²
b) Fuel oil pressure: 2.8 kg/cm²
c) Turbo Discharge pressure should be the same both in driver cab gauge and mercury
manometer in testing centre.
d) Booster Air pressure: 1.6-1.6-1.79 kg/cm² for 46"-52" DWM2 loco
1.7-9.0-1.79 kg/cm² for 52"-59" DWDG2 loco
e) Temperature of engine cooling water is 80°C
11. Air Brake tests: The Independent and auto brakes as well as the emergency brakes are
tested. Also the brake pipe and brake cylinders are tested for leakages. At the same time
compressors are tested either by orifice test or by the time taken to charge the main
reservoir from 0 kPa to 550.

40
Chapter 5
SCADA
5.1 What is SCADA?
Supervisory Control and Data Acquisition or simply SCADA is one of the solutions available
for data acquisition, monitor and control systems covering large geographical areas. It refers to the
combination of data acquisition and telemetry.

41
SCADA systems are mainly used for the implementation of monitoring and control system of an
equipment or a plant in several industries like power plants, oil and gas refining, water and waste
control,telecommunications,etc.
In this system, measurements are made under field or process level in a plant by number of remote terminal
units and then data are transferred to the SCADA central host computer so that more complete process or
manufacturing information can be provided remotely.This system displays the received data on number
of operator screens and conveys back the necessary control actions to the remote terminal units in process
plant.
5.2 Components of Typical SCADA System
The major components in SCADA system are
 Remote Terminal Units (RTUs)
RTU is the main component in SCADA system that has a direct connection with various sensors,
meters and actuators associated with a control environment.These RTUs are nothing but real-
time programmable logic controllers (PLCs) which are responsible for properly converting
remote station information to digital form for modem to transmit the data and also converts the
received signals from master unit in order to control the process equipment through actuators and
switchboxes.
 Master Terminal Units (MTUs)
A central host servers or server is called Master Terminal Unit, sometimes it is also called as SCADA
center. It communicates with several RTUs by performing reading and writing operations during
scheduled scanning. In addition, it performs control, alarming, networking with other nodes, etc.
 Communications System
The communication network transfers data among central host computer servers and the field data
interface devices & control units. The medium of transfer can be cable, radio, telephone, satellite, etc.
or any combination of these.

42
 Operator Workstations
These are the computer terminals consisting of standard HMI (Human Machine Interface) software
and are networked with a central host computer. These workstations are operator terminals that request
and send the information to host client computer in order to monitor and control the remote field
parameters.
Automation of Electrical Distribution System
Modern SCADA systems replace the manual labor to perform electrical distribution tasks and
manual processes in distribution systems with automated equipments. SCADA maximizes the
efficiency of power distribution system by providing the features like real-time view into the
operations, data trending and logging, maintaining desired voltages, currents and power factors,
generating alarms, etc.
SCADA performs automatic monitoring, protecting and controlling of various equipments in
distribution systems with the use of Intelligent Electronic Devices (or RTUs). It restores the power
service during fault condition and also maintains the desired operating conditions.
SCADA improves the reliability of supply by reducing duration of outages and also gives the cost-
effective operation of distribution system. Therefore, distribution SCADA supervises the entire
electrical distribution system. The major functions of SCADA can be categorized into following
types.
 Substation Control
 Feeder Control
 End User Load Control

44
5.4 SCADA System Architecture in DLW
Fig: Functional Units of SCADA

45
5.5 DLW Infrastructure under monitoring and conrol

46
5.5 DLW Ring
5.6 Advantages of Implementing SCADA systems for Electrical Distribution
 Due to timely recognition of faults, equipment damage can be avoided
 Continuous monitoring and control of distribution network is performed from remote locations
 Saves labor cost by eliminating manual operation of distribution equipment
 Reduce the outage time by a system-wide monitoring and generating alarms so as to address
problems quickly
 Improves the continuity of service by restoring service after the occurrence of faults (temporary)
 Automatically improves the voltage profile by power factor correction and VAR control
 Facilitates the view of historian data in various ways

47
5.7 DLW POWER SUPPLY DIAGRAM

48
Chapter 6
TELEPHONE EXCHANGE
6.1 Principles of Telephony
Telephony provides a means of sending information through human speeches when required
between two persons situated at a distance apart. In line telephony the information is sent
through the medium of line conductors between them.
 All Telephone Exchanges shall be
* Automatic
* Electronic
* Digital
* Stored Programme Controlled (SPC)
* Pulse Code Modulation (PCM, Time Division Multiplexing (TDM) technology.
a) Telephones: The apparatus that are used for transmitting and receiving speech signals are
called ”Telephones” and the persons who use them for sending information between them are
called “Subscribers”.
The telephone transmitter and telephone receiver must be such that the conversion from
speech sounds into electrical currents and vice-versa must be perfect ie. free from frequency
distortion, amplitude distortion.
b) Telephone exchange: It is a place where switching between two subscribers is done through
either manually or electronically. In addition to switching, signalling and controlling are
also done at “Exchange”.
c) Human speechand its transmission: Human speech consists of a large number of
frequency components of different values between 0.3 to 3.4 KHz having different amplitudes
and different phase relations between them.
Steps in Telephone transmission:
i) Conversion of speech sounds into the electrical voice frequency currents
at transmitting end.
ii) Transmission of speech currents through lines to the distant end.
iii) Conversion of voice frequency currents into speech sounds at the receiving end
d) Types of currents:

49
There are two types of currents to be generated in an exchange.
i) Speech currents- carry information between subscribers
ii) Signalling currents – carry the signalling information.
6.1.1 Cables used in Telephony:
In line telephony speech currents are carried by lines first into the exchange and there to the
receiver of the called subscriber through separate pair of lines. The type of transmission lines
used are generally insulated copper conductors, which are formed into a bunch of 10, 20,50 or
100 pairs called as “Telephone cables”.
The copper is used for Telephony transmission due to, less attenuation and less distortion
provided that the insulation resistance of conductor is within the given values.
a) Characteristics of Telecomcables:
Sl.No Lb/Mile Kg/Km Copper conductor
Di in mm
Loop resistance
per Km in Ω
DB loss per
KM
1 6.5 1.85 O.51 182 1.379
2 10 2.84 0.63 114 O.91
3 20 5.68 0.90 56 0.75
4 40 11.36 1.24 27.4 0.43
6.2 Basics of Telephone Exchange
It is a place where switching between two subscribers is done through either manually or
electronically. In addition to switching, signalling and controlling are also done at exchange.
It consists of the following functional blocks:
a) Main Distribution Frame.
b) Card Frame.
c) Mother board.
d) Power supply panel with protective devices .
a)Main Distribution Frame (MDF):
In a Telephone exchange different subscribers from different places are terminated on a
frame called “ Main Distribution Frame” (MDF) in the exchange and from there they are
extended to subscribers line cards/Trunk cards kept in the exchange rack. Protective
devices are located in the MDF.

50
 Purpose of MDF:
There are three purposes of MDF,
1) It isthe place where bothexternal andinternal cablesare terminated
The cross connection between the two cables conductors is done on the MDF and this is
done by means of jumper wires (Red & White).
2) It carriesall the protective devicesusedinthe exchange. Theyare Fuses,Heatcoils&
Lightningprotectors.
3) The MDF is the mostsuitable place fortesting purposes.
b)Card Frame:
It contains different slots in which the nominated cards are to be inserted. It is different in
different types of exchanges.
c)Mother board:
It connectivity between different cards. It is a PCB with 1,2,3 layers.
d)Power supply panel:
It provides power supply to different cards in the exchange at different low D.C. voltages. It also
includes protective devices like fuses etc.
6.3 Main functional areas in Telephone Exchange:
a) Switching Function: The switching functions are carried out through the switching
network, which provides a temporary path for simultaneous, bi-directional speech between,
!)Twosubscribers connectedtothe same exchange.Thisiscalledas“Local switching”
ii) Two subscribersconnectedtodifferentexchanges.Thisisknownas“Trunk switching”.
iii) Pairsof trunkstowardsdifferentexchanges.Thisisknownas“Transit switching”
b) Signalling function: The signaling function enables the various equipment in a network to
communicate with each other in order to establish and supervise the calls. It is of two types,
i) subscriber line signalling: It enables the exchange to identify calling subscribers line,
extend dial tone, receive the dialed digits, extend the ringing voltage to the called
subscriber, extend the ring back tone to the calling subscriber to indicate the called

51
subscriber is being is being connected. In the event the called subscriber is busy, engage
tone is sent to the calling subscriber.
ii) Inter exchange signalling: It enables a call to be set up, supervised and cleared between
exchanges.
c) Controlling function: The controlling function performs the task of processing the signalling
information and controlling the operation of the switching network.
The control functions may be,
i) Wired logic control: In this pre wiring is done between different speech path devices
and common control. Any changes are required in facilities of subscribers or
introduction of new services require wiring changes.
ii) Stored Programme Control (SPC): After introduction of microprocessor, stored
programme control system and is came into use. In this system the establishment and
supervision of the connections in the exchange is under the control of “Microprocessor”,
which is suitably programmed.

52
Chapter 7
CONCLUSION
INNOVATIONS IN GLOBAL LOCOMOTIVES
Why diesel-electric locos?
Diesel is a non renewable source of energy and can’t be replenished once finished. So why not go for
electric locomotives, which pick up electrical power from an overhead wire or a third rail laid beside the
track? When I asked this question from my project guide, he simply answered that the cost of electric
transmission lines is huge and also the first cost of an electric locomotive is far greater than a diesel
locomotive. Hence even at those places where transmission lines have been laid, diesel-electric locos are
still used!
Recent trends
Recent innovations in technology have been driven by a desire to find safer, faster, and more reliable
means of getting from place to place. For passenger transportation, speed and convenience are primary
goals. For freight transportation, speed, reliability, and efficiency, or carrying more cargo for less
money and arriving on time, have been the motivating factors.
The diesel-electric locomotives cannot go on indefinitely and there is need to look for smarter methods
in locomotive transport sector. Most modern transportation systems rely on petroleum for energy, but
this source of energy is finite and creates serious environmental effects when used in the internal-
combustion engine. Research into alternative fuel sources, such as electrical storage, natural gas,
methanol, ethanol, fuel cells, and solar energy, will continue in order to ensure a reliable supply of
energy for the transportation systems of the world. Several new forms of propulsion are also being
investigated.
Several technologies that are shaping society in a variety of ways will likely characterize the future of
locomotive transportation. Intelligent transportation systems apply the latest advances in computers and
electronics to better control vehicle operations. Computerized road maps used with the Global
Positioning System (GPS) help drivers to navigate.
Research is also being conducted into improving the materials used for constructing the locomotives.
Composite material, which is a hybrid consisting of many different component materials, can provide
lightweight, extremely strong, and highly durable material for loco construction. With the lighter
weight, locos can become more fuel efficient.
Explained on the following page is the working of a magnetically levitated locomotive that very
surely is the technology of the future!

53
Chapter 8
REFRENCE
SITES
http://www.howstuffworks.com/diesel.htm
http://en.wikipedia.org/
http://www.google.com (Google search engine)
http://diesellocoworks.com
ENCYCLOPAEDIAS
Microsoft ® Encarta ® 2007
Britannica Student Version Encyclopaedia ® 2003

DLW SUMMER TRAINING REPORT FOR ECE BRANCH

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