DEPARTMENT OF ELECTRICAL & ELECTRONICS

ENGINEERING

CERTIFICATE

This is to certify that Mr. of B.Tech. IV Yr. has prepared this seminar

report entitled “ ” under my guidance and supervision in the

session 2011-15.It has been presented and submitted towards the partial fulfilment

for the award of degree of bachelor of technology in Electrical & Electronics

Engineering.

Miss. Neha Goyal Mr. Gopal Verma

Asst. Professor Head of Department

(Seminar In-charge) (Seminar Guide)

Acknowledgement

I would like to express my deepest gratitude also extend my heartfelt thanks to my

seminar guide Mr. Gopal Verma Head of Department Electrical & Electronics

Engineering who very sincerely extended his help and provided resourceful and helpful

inputs without which the work would never have been realized. I extend my cordial

gratitude and esteem to my teachers, whose effective guidance, valuable time and

constant inspiration made it feasible and easy to carry out the work in a smooth manner.

I am extremely grateful to Miss. Neha Goyal Professor for her invaluable support

which just cannot be put into words and who was also an edifice of encouragement.

Last but not the least, I would like to thank all my friends who directly or indirectly

helped me in completion of my work.

YOUR NAME

Roll no. 11477210

B. Tech. IV Year

Electrical & Electronics Engineering

Page Of Contents

Chapter – 1

INTRODUCTION TO ELECTRICAL LOCOMOTIVE

1.1 Introduction

1.2 Characterstics

1.3 History in india

Chapter – 2

TRACTION SYSTEMS FOR LOCOMOTIVES

2.1 Introduction

2.2 Types of electric locomotives in Indian Railways

2.3 Traction Motors In Locomotives

2.3.1 Mounting of motors

2.3.2 Windings

2.3.3 Power control

2.3.4 Dynamic braking

2.3.5 Automatic acceleration

2.4 Three Phase AC Railway electrification

2.4.1 Advantages

2.4.2 Disadvantages

2.5 Overview Of Traction Offerings

Chapter – 3

AUXILIARY MACHINES AND EQUIPMENTS IN ELECTRIC

LOCOMOTIVES

3.1 Introduction

3.2 Auxiliaries of The Transformers

3.2.1 Transformer Oil Circulating Pump (MPH)

3.2.2 Transformer Oil Cooling Radiator Blower (MVRH)

3.3 Auxiliaries of Rectifiers Block

3.4 Auxiliaries of smooth reactors

3.5 Auxiliaries of traction maotors

3.6 Other auxiliaries

3.6.1 Air Compressors (MCP 1, MCP-2, MCP-3)

3.6.2 Vacuum Pumps (MPV 1 & 2)

3.6.3 Dynamic Braking resistance Cooling Blower (MVRF)

3.6.4 Main Starting Resistance Cooling Blowers (MVMSR)

3.7 Power supply

3.7.1 Arno Convertor

3.7.1.1 Precautions during arno starting

3.7.2 Static Invertor

3.7.3 Motor-Alternator Set (used only in the WCAM-1 and the WCG-2 locos)

Chapter – 4

RESEARCH, DESIGN&DEVELOPMENT

4.1 Development of Electric locomotive with Head On Generation (HOG) facility

4.2 HOG System Provided in WAP7 Locomotive

4.3 Modification in brake rigging arrangement and up gradation of speed of

WAP7 locomotives

4.4 Development of high horse power locomotives for Heavy Haul Operation

4.5 Up gradation of WAP5 Locomotives for Service Speed of 200kmph

4.6 Development of oil free compressors

4.7 Development of Air operated pantograph

4.8 Improved cooling arrangement for Electronic cards

4.9 Standardization of maintenance/fitment practices of Equalizer and

Compensating Beam Pins and Cotters inWAG7locomotives

4.10 Development of Hall Effect Speed Sensors

4.11 Maintenance of Traction motor support plate and Bogie nose to prevent

crack/ breakage of Traction motor support plate (Holder for Traction motor

suspension)

CHAPTER-1

INTRODUCTION TO ELECTRICAL LOCOMOTIVE

1.1 Introduction

An electric locomotive is a locomotive powered by electricity from overhead lines,

a third rail or on-board energy storage such as a battery or fuel cell. Electric locomotives

with on-board fuelled prime movers, such as diesel engines or gas turbines, are classed

as diesel-electric or gas turbine-electric locomotives because the electric generator/motor

combination serves only as a power transmission system. Electricity is used to eliminate

smoke and take advantage of the high efficiency of electric motors, but the cost of

electrification means that usually only heavily used lines can be electrified.

1.2 Characteristics

One advantage of electrification is the lack of pollution from the locomotives.

Electrification results in higher performance, lower maintenance costs and lower energy

costs.

Power plants, even if they burn fossil fuels, are far cleaner than mobile sources such as

locomotive engines. The power can come from clean or renewable sources,

including geothermal power, hydroelectric power, nuclear power, solar power and wind

turbines. Electric locomotives are quiet compared to diesel locomotives since there is no

engine and exhaust noise and less mechanical noise. The lack of reciprocating parts

means electric locomotives are easier on the track, reducing track maintenance.

Power plant capacity is far greater than any individual locomotive uses, so electric

locomotives can have a higher power output than diesel locomotives and they can

produce even higher short-term surge power for fast acceleration. Electric locomotives

are ideal for commuter rail service with frequent stops. They are used on high-speed

lines, such as ICE in Germany, Acela in the U.S., Shinkansen in Japan, China Railway

High-speed in China and TGV in France. Electric locomotives are used on freight routes

with consistently high traffic volumes, or in areas with advanced rail networks.

Electric locomotives benefit from the high efficiency of electric motors, often above

90% (not including the inefficiency of generating the electricity). Additional efficiency

can be gained from regenerative braking, which allows kinetic energy to be recovered

during braking to put power back on the line. Newer electric locomotives use AC motor-

inverter drive systems that provide for regenerative braking.

The chief disadvantage of electrification is the cost for infrastructure: overhead lines or

third rail, substations, and control systems. Public policy in the U.S. interferes with

electrification: higher property taxes are imposed on privately owned rail facilities if

they are electrified. U.S. regulations on diesel locomotives are very weak compared to

regulations on automobile emissions or power plant emissions.

In Europe and elsewhere, railway networks are considered part of the national transport

infrastructure, just like roads, highways and waterways, so are often financed by the

state. Operators of the rolling stock pay fees according to rail use. This makes possible

the large investments required for the technically, and in the long-term also,

economically advantageous electrification. Because railroad infrastructure is privately

owned in the U.S., railroads are unwilling to make the necessary investments for

electrification.

1.3 History in India

A plan for a rail system in India was first put forward in 1832. The first rail line of the

Indian sub-continent came up near Chintadripet Bridge (presently in Chennai) in Madras

Presidency in 1836 as an experimental line. In 1837, a 3.5-mile (5.6 km) long rail line

was established between Red Hills and stone quarries near St. Thomas Mount. In 1844,

the Governor-General of India Lord Hardinge allowed private entrepreneurs to set up a

rail system in India. The East India Company (and later the British Government)

encouraged new railway companies backed by private investors under a scheme that

would provide land and guarantee an annual return of up to five percent during the initial

years of operation. The companies were to build and operate the lines under a 99-year

lease, with the government having the option to buy them earlier.[8]

Two new railway companies, Great Indian Peninsular Railway (GIPR) and East Indian

Railway (EIR), were created in 1853–54 to construct and operate two 'experimental'

lines near Mumbai and Kolkata respectively. The first train in India had become

operational on 22 December 1851 for localized hauling of canal construction material

in Roorkee. A year and a half later, on 16 April 1853, the first passenger train service

was inaugurated between Bori Bunder in Mumbai and Thane. Covering a distance of 34

kilometers (21 mi), it was hauled by three locomotives, Sahib, Sindh, and Sultan. This

was soon followed by opening of the first passenger railway line in North India between

Allahabad and Kanpur on 3 March 1859.

In 1854 Lord Dalhousie, the then Governor-General of India, formulated a plan to

construct a network of trunk lines connecting the principal regions of India. Encouraged

by the government guarantees, investment flowed in and a series of new rail companies

were established, leading to rapid expansion of the rail system in India. Soon various

native states built their own rail systems and the network spread to the regions that

became the modern-day states of Assam, Rajasthan and Andhra Pradesh. The route

mileage of this network increased from 1,349 kilometers (838 mi) in 1860 to 25,495

kilometers (15,842 mi) in 1880 – mostly radiating inland from the three major port cities

of Mumbai, Madras, and Calcutta. Most of the railway construction was done by Indian

companies. The railway line from Lahore to Delhi was done B.S.D. Bedi and Sons

(Baba Shib Dayal Bedi), this included the building of the Jamuna Bridge. By 1895, India

had started building its own locomotives, and in 1896 sent engineers and locomotives to

help build the Uganda Railway. At the beginning of the twentieth century India had a

multitude of rail services with diverse ownership and management, operating on broad,

meter and narrow gauge networks. In 1900 the government took over the GIPR network,

while the company continued to manage it. With the arrival of the First World War, the

railways were used to transport troops and food grains to the port city of Mumbai and

Karachi en route to UK, Mesopotamia, East Africa etc. By the end of the First World

War, the railways had suffered immensely and were in a poor state. In 1923, both GIPR

and EIR were nationalized with the state assuming both ownership and management

control The Second World War severely crippled the railways as rolling stock was

diverted to the Middle East, and the railway workshops were converted into munitions

workshops After independence in 1947, forty-two separate railway systems, including

thirty-two lines owned by the former Indian princely states, were amalgamated to form a

single unit named the Indian Railways. The existing rail networks were abandoned in

favor of zones in 1951 and a total of six zones came into being in 1952.

As the economy of India improved, almost all railway production units were

‘indigenized’ (produced in India). By 1985, steam locomotives were phased out in favor

of diesel and electric locomotives. The entire railway reservation system was

streamlined with computerization between 1987 and 1995.

In 2003, the Indian Railways celebrated 150 years of its existence. Various zones of the

railways celebrated the event by running heritage trains on routes similar to the ones on

which the first trains in the zones ran. The Ministry of Railways commemorated the

event by launching a special logo celebrating the completion of 150 years of

service. Also launched was a new mascot for the 150th year celebrations, named "Bholu

the guard elephant

CHAPTER-2

TRACTION SYSTEMS FOR LOCOMOTIVES

2.1 Introduction

Indian Railways use a specialized classification code for identifying its locomotives. The

code is usually three or four letters, followed by a digit identifying the model (either

assigned chronologically or encoding the power rating of the locomotive).This could be

followed by other codes for minor variations in the base model.

The three (or four) letters are, from left to right, the gauge of tracks on which the

locomotive operates, the type of power source or fuel for the locomotive, and the kind of

operation the locomotive can be used for. The gauge is coded as 'W' for broad gauge, 'Y'

for meter gauge, 'Z' for the 762 mm narrow gauge and 'N' for the 610 mm narrow gauge.

The power source code is 'D' for diesel, 'A' for AC traction, 'C' for DC traction and 'CA'

for dual traction (AC/DC). The operation letter is 'G' for freight-only operation, 'P' for

passenger trains-only operation, 'M' for mixed operation (both passenger and freight)

and 'S' for shunting operation. A number alongside it indicates the power rating of the

engine. For example '4' would indicate a power rating of above 4,000 hp (2,980 kW) but

below 5,000 hp (3,730 kW). A letter following the number is used to give an exact

rating. For instance 'A' would be an additional 100 horsepower (75 kW); 'B' 200 hp

(150 kW) and so on. For example, a WDM-3D is a broad-gauge, diesel-powered, mixed

mode (suitable for both freight and passenger duties) and has a power rating of

3400 hp (2.5 MW).

The most common diesel engine used is the WDM-2, which entered production in 1962.

This 2,600 hp (1.9 MW) locomotive was designed by Alco and manufactured by

the Diesel Locomotive Works, Varanasi, and is used as a standard workhorse. It is being

replaced by more modern engines, ranging in power up to 5,500 hp (4.1 MW).

There is a wide variety of electric locomotives used, ranging between 2,800 to 6,350 hp

(2.1 to 4.7 MW). They also accommodate the different track voltages in use. Most

electrified sections in the country use 25,000 volt AC, but railway lines

around Mumbai use the older 1,500 V DC system. Thus, Mumbai and surrounding areas

are the only places where one can find AC/DC dual locomotives of the WCAM and

WCAG series. All other electric locomotives are pure AC ones from the WAP, WAG

and WAM series. Some specialized EMU (electric multiple units) are running on

Mumbai Suburban System of Central Railway and Western Railway also use dual-power

systems, these are new-age rakes manufactured in ICF (Integral Coach Factory) in

Paramour usually white and purple livery color. There are also some very rare battery-

powered locomotives, primarily used for shunting and yard work.

The only steam engines still in service in India operate on two heritage lines

(Darjeeling and Ooty), and on the tourist train Palace on Wheels Plans are afoot to re-

convert the Neral-Matheran to steam. The oldest steam engine in the world in regular

service, the Fairy Queen, operates between Delhi and Alwar.

2.2 Types of electric locomotives in Indian Railways

Mixed type locomotives; WDM 1 (first mainline diesel electric locomotives used

in India. Introduced in 1957. Imported from ALCO. Out of service now. 1950hp)

WDM2 (Most widely used and first homemade mainline diesel-electric

locomotives in India. Original prototypes were made by Alco. Introduced in

1962, more than 2700 have been made. Rated at 2600 hp) WDM 2A (Technical

variants of WDM 2) WDM2BWDM 3 (Only 8 were imported. They used

hydraulic transmission and are currently non- functional)WDM 3A (Formerly

WDM 2C. Another WDM 2 variant. It is not related to WDM3. 3100 hp)WDM

3C, (higher powered versions of WDM 3A)WDM 3DWDM 4 (Entered service

along with WDM 2. Prototypes designed by General Motors. Though considered

superior to WDM 2 in many ways, these locomotives weren’t chosen as General

Motors did not agree to a technology transfer agreement. 2600 hp)WDM 6 (Very

rare class; only two were made; one is being used by Puttalam Cement Factory in

Sri Lanka. Rated at 1200 HP)WDM 7 they were designed for branch-line duties,

but they are now used mostly for shunting. Rated at 2000hpWDM 5 No

locomotive class was designated as WDM5 in India. Passenger Locomotives:

WDP 1WDP 2 (New class name WDP 3A. Dedicated passenger diesel

locomotive. Entered service in 1998. Powerful locomotive. 3100 hp)WDP 3 This

locomotives are actually prototypes of the class WDP 1 and never entered serial

production WDP 4 EMD (former GM-EMD) GT46PAC, fundamentally a

passenger version of the WDG 4 (GT46MAC). 4000 hp WDP 4B EMD (former

GM-EMD) GT46PAC, An improved version of the WDP 4, this is a more

powerful version and has 6 traction motors, just like the WDG 4. Also comes

with wider cabin to aid visibility and minor exterior design changes. 4500 hp

WDP 4D EMD (former GM-EMD) GT46PAC, This is basically a WDP 4B with

twin cabs. Minor changes were made to the locomotive to facilitate the addition

of a second cabin. This locomotive comes with LC Instrument display and toilet

for the drivers. As of now, two units have been made and are expected to enter

full-time service soon. 4500 hp.

Goods locomotives: WDG 2 New class name WDG 3A. These class is actually a

technically upgraded form of WDM 2WDG 3B, Technical upgraded forms of

WDG 2 or WDG 3AWDG 3C,WDG 3DWDG 4 New dedicated goods

locomotives. These are General motors GT46MAC models. First units were

imported in 1999. They are numbered from #12000 upward. Local production

started on 2002. 4000 hp Shunting locomotives (Also known as switching

engines):WDS 1 First widely deployed and successful diesel locomotives used in

India. Imported in 1944- 45. Currently out of service. 386 HPWDS 2 Currently

out of service WDS 3 All locomotives of this class were rebuilt and reclassified

as WDS 4C in 1976-78. 618 HPWDS 4, Designed by Chittaranjan Locomotive

Works. 600-700 hp WDS 4A,WDS 4B,WDS 4DWDS 4C Rebuilt WDS 3 locos

as mentioned above WDS 5 Some of these locomotives are used for industrial

shunting. A few are used on Indian Railways. Rated at 1065hpWDS 6 Heavy-

haul shunters made in large numbers for industrial concerns as well as for Indian

Railways Rated at 1200/1350hpWDS 8 Only five of these were made, and all

were transferred to steel works 800hpNote: There is no electric shunting engine

in India. Classes from WDS 1 to WDS 4D have hydraulic transmission. The

WDS 4, 4A, 4B, 4C and 4D are the only still existing broad gauge locomotives

with diesel-hydraulic transmission. Diesel multiple units: A few routes in India

currently have Diesel multiple unit service. Depending on the transmission

system they are classified as DEMU (diesel-electric transmission) or DHMU

(diesel-hydraulic transmission).There are diesel railcar services in a few places

known as railbus. DC electric traction Note: These locomotives are, or were used

only in sections around Mumbai which is the only location in India

Mixed type locomotives: WCM 1 First electric locomotives with the now

familiar Co-Co wheel arrangement to be used in India. 3700 hp WCM 2

520hpWCM 3 600hp - Used in Kolkata , then transferred to Mumbai, Built by

Hitachi WCM 4 675hp - Also built by Hitachi WCM 5 Built by Chittaranjan

locomotive works to RDSOs design specifications. Auxiliaries by Westinghouse

and North Boyce. Built in 1962, these are India’s first indigenously designed DC

electric locomotives. The first was named Lokamanya after the Congress leader

Bal Gangadhar Tilak. 3700 hp WCM 6 A rare and highly powerful class. 5000

hp, only two were built. Now converted to run on AC power, class name changed

to WAM 4Passenger locomotives: WCP 1, WCP 2 Historically very important

locomotives as these are the very first electric loco(GIPR EA/1 and EA/2 to be

used in India. The first locomotive was named as Sir Roger Lumney and is

currently preserved in the National Rail Museum, New Delhi. 2160 hp WCP 3,

WCP 4 GIPR EB/1 and EC/1, these are also among the earliest electric locos

used in India Goods locomotives: WCG 1 These are Swiss crocodile locomotives

imported in 1928 from Swiss locomotive works.(GIPR EF/1 These are among

the earliest electric locos used in India. The first locomotive was named as Sir

Leslie Wilson and is currently preserved in the National Rail Museum, New

Delhi. 2600-2950 hp WCG 2 Designed by Chittaranjan locomotive works in

1970AC electric traction The 25 kV AC system with overhead lines is used

throughout the rest of the country. Mixed type locomotives WAM 1 Among the

first AC electric locomotives used in India. Introduced in 1959. Now out of

service. 3010 hp WAM 2WAM 3WAM 4 Indigenously designed by Chittaranjan

Locomotive Works in 1970. Highly powerful class. One of the most successful

locomotives in India. 3850 hp Passenger locomotives WAP 1 Designed by

Chittaranjan locomotive works in 1980 for the Kolkata-Delhi Rajdhani Express.

A very successful class. 3900 hpWAP 2 Not in use

WAP 3 Not in use WAP 4 Upgraded from WAP 1 for higher loads by

Chittaranjan locomotive works in 1994. One of the most successful locomotives

in India. Very powerful class. 5350 hp WAP 5 Imported in 1995 from

Switzerland and used on premier express trains. 5450 hp WAP 6 Only found

near Asansol WAP 7 Same design as WAG 9 with modified gear ratio. Highly

powerful class. 6250 hp Goods locomotives WAG 1WAG 2WAG 3WAG

4WAG 5 The most successful electric locomotives in India. Designed by

chittaranjan locomotive works in 1984. More than 1100 were made. 3850

hpWAG 5A, Technical variants of WAG 5WAG 5BWAG 6A Imported from

ASEA and Hitachi. 6110 hpWAG 6B, Variants of WAG 3A. All rated at 6110

hpWAG 6cWAG 7 Very successful class. Designed by chittaranjan locomotive

works. 5000 hpWAG 9 Currently the most powerful class in India, rated at 6350

hp. Same design as WAP 7 with modified gear ratio. Designed by Adtranz,

Switzerland Dual (both AC and DC) traction Note: These locomotives are, or

were used only in sections around Mumbai which is the only location in India

still using DC traction. They can run under AC traction too. The main purpose

behind the manufacture of these types of locomotives was to provide

transportation in and out Mumbai area without changing the engine. Mixed type

locomotives:WCAM 1WCAM 2WCAM 3 Designed by Bharat Heavy Electricals

locomotives:WCAG 1 Designed by Bharat heavy electrical limited. 2930 hp

under DC traction and 4720 hp under AC traction Note There is no dedicated

dual current Limited. 4600 hp under DC traction and 5000 hp under AC traction

Goods passenger locomotive in India, but in Mumbai area, there are some EMUs

which can run under dual traction.

2.3 Traction Motors In Locomotives

Traction motor refers to an electric motor providing the primary rotational torque to a

machine, usually for conversion into linear motion (traction).

Traction motors are used in electrically powered rail vehicles such as electric multiple

units and electric locomotives, other electric vehicles such as electric milk

floats, elevators, conveyors, and trolleybuses, as well as vehicles with electrical

transmission systems such as diesel-electric, electric hybrid vehicles and battery electric

vehicles. Additionally, electric motors in other products (such as the main motor in

a washing machine) are described as traction motors. Traditionally, these were series-

wound brushed DC motors, usually running on approximately 600 volts. The availability

of high-powered semiconductors (such as thyristors and the IGBT) has now made

practical the use of much simpler, higher-reliability AC induction motors known as

asynchronous traction motors. Synchronous AC motors are also occasionally used, as in

the French TGV.

2.3.1 Mounting of motors

Before the mid-20th century, a single large motor was often used to drive

multiple driving wheels through connecting rods that were very similar to those used

on steam locomotives. Examples are the Pennsylvania Railroad DD1, FF1 and L5 and

the various Swiss Crocodiles. It is now standard practice to provide one traction motor

driving each axle through a gear drive.

Usually, the traction motor is three-point suspended between the bogie frame and the

driven axle; this is referred to as a "nose-suspended traction motor". The problem with

such an arrangement is that a portion of the motor's weight is unsprang, increasing

unwanted forces on the track. In the case of the famous Pennsylvania Railroad GG1, two

bogie-mounted motors drove each axle through a quill drive. The "Bi-Polar" electric

locomotives built by General Electric for the Milwaukee Road had direct drive motors.

The rotating shaft of the motor was also the axle for the wheels. In the case of French

TGV power cars, a motor mounted to the power car’s frame drives each axle; a "tripod"

drive allows a small amount of flexibility in the drive train allowing the trucks bogies to

pivot. By mounting the relatively heavy traction motor directly to the power car's frame

rather than to the bogie, better dynamics are obtained allowing better high-speed

operation.

2.3.2 Windings

The DC motor was the mainstay of electric traction drives on both electric and diesel-

electric locomotives, street-cars/trams and diesel electric drilling rigs for many years. It

consists of two parts, a rotating armature and fixed field windings surrounding the

rotating armature mounted around a shaft. The fixed field windings consist of tightly

wound coils of wire fitted inside the motor case. The armature is another set of coils

wound round a central shaft and is connected to the field windings through "brushes"

which are spring-loaded contacts pressing against an extension of the armature called

the commutator. The commutator collects all the terminations of the armature coils and

distributes them in a circular pattern to allow the correct sequence of current flow. When

the armature and the field windings are connected in series, the whole motor is referred

to as "series-wound". A series-wound DC motor has a low resistance field and armature

circuit. Because of this, when voltage is applied to it, the current is high due to Ohm's

law. The advantage of high current is that the magnetic fields inside the motor are

strong, producing high torque (turning force), so it is ideal for starting a train. The

disadvantage is that the current flowing into the motor has to be limited, otherwise the

supply could be overloaded or the motor and its cabling could be damaged. At best, the

torque would exceed the adhesion and the driving wheels would slip. Traditionally,

resistors were used to limit the initial current.

2.3.3 Power control

As the DC motor starts to turn, interaction of the magnetic fields inside causes it to

generate a voltage internally. This back EMF (electromagnetic force) opposes the

applied voltage and the current that flows is governed by the difference between the two.

As the motor speeds up, the internally generated voltage rises, the resultant EMF falls,

less current passes through the motor and the torque drops. The motor naturally stops

accelerating when the drag of the train matches the torque produced by the motors. To

continue accelerating the train, series resistors are switched out step by step, each step

increasing the effective voltage and thus the current and torque for a little bit longer until

the motor catches up. This can be heard and felt in older DC trains as a series of clunks

under the floor, each accompanied by a jerk of acceleration as the torque suddenly

increases in response to the new surge of current. When no resistors are left in the

circuit, full line voltage is applied directly to the motor. The train's speed remains

constant at the point where the torque of the motor, governed by the effective voltage,

equals the drag - sometimes referred to as balancing speed. If the train starts to climb an

incline, the speed reduces because drag is greater than torque and the reduction in speed

causes the back-EMF to fall and thus the effective voltage to rise - until the current

through the motor produces enough torque to match the new drag. The use of series

resistance was wasteful because a lot of energy was lost as heat. To reduce these

losses, electric locomotives and trains (before the advent of power electronics) were

normally equipped for series-parallel control as well.

2.3.4 Dynamic braking

If the train starts to descend a grade, the speed increases because the (reduced) drag is

less than the torque. With increased speed, the internally generated back-EMF voltage

rises, reducing the torque until the torque again balances the drag. Because the field

current is reduced by the back-EMF in a series wound motor, there is no speed at which

the back-EMF will exceed the supply voltage, and therefore a single series wound DC

traction motor alone cannot provide dynamic or regenerative braking.

There are, however various schemes applied to provide a retarding force using the

traction motors. The energy generated may be returned to the supply (regenerative

braking), or dissipated by on board resistors (dynamic braking). Such a system can bring

the load to a low speed, requiring relatively little friction braking to bring the load to a

full stop.

2.3.5 Automatic acceleration

On an electric train, the train driver originally had to control the cutting out of resistance

manually, but by 1914, automatic acceleration was being used. This was achieved by an

accelerating relay (often called a "notching relay") in the motor circuit which monitored

the fall of current as each step of resistance was cut out. All the driver had to do was

select low, medium or full speed (called "shunt", "series" and "parallel" from the way

the motors were connected in the resistance circuit) and the automatic equipment would

do the rest.

2.4 Three Phase AC Railway electrification

Three-phase AC railway electrification was used in Italy, Switzerland and the United

States in the early twentieth century. Italy was the major user, from 1901 until 1976,

although lines through two tunnels also used the system; the Simplon Tunnel in

Switzerland from 1906 to 1930, and the Cascade Tunnel of the Great Northern

Railway in the United States from 1909 to 1939. The first line was in Switzerland, from

Burgdorf to Thun (40 km or 25 mi), since 1899

2.4.1 Advantages

The system provides regenerative braking with the power fed back to the system, so is

particularly suitable for mountain railways (provided the grid or another locomotive on

the line can accept the power). The locomotives use three-phase induction motors.

Lacking brushes and commutators, they require less maintenance. The early Italian and

Swiss systems used a low frequency (16⅔ Hz), and a relatively low voltage (3,000 or

3,600 volts) compared with later AC systems.

2.4.2 Disadvantages

The overhead wiring, generally having two separate overhead lines and the rail for the

third phase, was more complicated, and the low-frequency used required a separate

generation or conversion and distribution system. Train speed was restricted to one to

four speeds, with two or four speeds obtained by pole-changing or cascade operation or

both.

2.5 Overview Of Traction Offerings

[1] Traction transformer

[2] Traction converter

[3] Traction control

[4] Train Control and Monitoring System

[5] Traction motor

[6] Diesel engine generator

[7] Auxiliary converter

[8] Battery charger

[9] Energy storage

CHAPTER-3

AUXILIARY MACHINES AND EQUIPMENTS IN ELECTRIC

LOCOMOTIVES

3.1 Introduction

Electric locos derive tractive effort from Traction Motors which are usually placed in the

bogie of the locomotive. Usually one motor is provided per axle but in some older

generation of locos two axles were driven by a single Traction Motor also.

However apart from Traction Motors, many other motors and equipment are provided in

electric locos. These motors are collectively known as the Auxiliaries. The aim of this

article is to provide an insight into the various Auxiliary Machines provided in the

Electric Locos operational on the Indian Railways.

But to understand the reasons why these auxiliaries are needed, it is necessary to

understand the manner in which the electric locos operate. An important part of the

electric loco is the Power Circuit. A short description of the power circuit of Electric

Locos operational on the Indian Railways can be seen here. The article referred

to describes the main components of the Power Circuit of the Electric Locomotive

comprising of the following parts:

1 Transformer (including Tap-Changer)

2 Rectifier

3 Smoothing Reactor

4 Traction Motors

5 Main Starting Resistances (in DC Traction on Dual Power Locos only)

6 Dynamic Braking Resistance Cooling Blower

A common feature running through all the above electrical equipments is that all of

these generate a lot of heat during their normal operation. Even when they are not in use,

they might generate a nominal amount of heat. Normally any electrical equipment

generates heat as by-product during operation. But traction vehicles tend to generate

more heat than normal. This is because day-by-day the demand on traction vehicles is

increasing. But an increase in the power output more or less translates into increased size

of the relevent equipments too. But a major problem with traction vehicles is that you

cannot increase their size beyond a certain limit. This is due to "Loading Guage

Restrictions". Hence, the power output of the locomotives has to be increased indirectly

without increasing their size. This is done by "pumping"more power through the

equipments and cooling them at a suitable rate at the same time.

Hence the different auxiliaries provided for cooling and other purposes in these locos is

described below. All the motors are of the AC 3 Phase squirrel cage induction type and

require very little maintenance and are simple and robust. They are described with

regard to their relationship to the major power equipment.

3.2 Auxiliaries of The Transformers

There are various type of transformers auxiliaries are as follows:

3.2.1 Transformer Oil Circulating Pump (MPH)

The transformer tank is filled with oil which serves two purposes. It provides enhanced

insulation to the transformer and its surroundings and the oil absorbs the heat generated

in the transformer and takes it away to the Transformer Oil Cooling Radiator. The

circulation of this oil is carried out by the MPH.

A flow valve with an electrical contact is provided in the oil circulating pipe. As long as

the oil is circulating properly, the contacts on the relay remain closed. However, in case

the MPH fails or stops the relay contacts open which in turn trips master auxiliary

protection relay Q-118. This trips the main circuit-breaker(DJ) of the loco. Thus the

transformer is protected.

3.2.2 Transformer Oil Cooling Radiator Blower (MVRH)

The MPH circulates the transformer oil through a radiator array on top of the

transformer. Air is blown over the radiator by the MVRH. This discharges the heat from

the radiator into the atmosphere. A flow detecting relay is provided in the air-stream of

the MVRH. The flow detector is a diaphragm type device. The flow of air presses the

diaphragm which closes an electrical contact. This relay is known as the QVRH. In case

the MVRH blower fails the the QVRH releases and trips the DJ through the relay Q-118.

3.3 Auxiliaries of Rectifiers Block

Rectifier Cooling Blowers-MVSI-1 and MVSI-2

One blower is provided for each of the rectifier blocks. As rectifiers are semiconductor

devices, they are very sensitive to heat and hence must be cooled continously. The

switching sequence of the MVSI blowers is setup in such a way that unless the blowers

are running, traction cannot be achieved. A detection relay of diaphragm type is also

provided in the air stream of these blowers. However, the detection relay (QVSI-1 &

2)are interlocked with a different relay known as Q-44. This is a much faster acting relay

with a time delay of only 0.6 seconds. Hence the failure of a MVSI blower would trip

the DJ in less than 1 second.

3.4 Auxiliaries of smooth reactors

In WAM-4 locos only one MVSL blower is provided for the cooling of the Smoothing

Reactors SL 1 & 2. However in WAG-5 and other locos two blowers namely MVSL

1&2 are provided for each of the SL's. Their running is "proved*"by the Q-118 relay.

*In railway parlance Proving means to verify whether an equipment or device is

working properly.

3.5 Auxiliaries of traction maotors

In the course of normal operation the traction motors also generate a lot of heat. This

heat is dissipated by two blowers namely MVMT 1 & 2 which force air through a duct

into the traction motors of Bogie-1 namely TM-1, TM-2, TM-3 and Bogie-2 namely

TM-4, 5, 6 respectively. The traction motor cooling blowers require a large quantity of

air which is taken from vents in the side-wall of the loco. Body-side filters are provided

to minimise the ingress of dust into the loco. Their running is detected by Air-Flow

sensing relay QVMT 1 & 2 (Pic-2) which in turn give there feed to the Q-118 relay.

3.6 Other auxiliaries

There are many other helping machines which are used in locomotives widely

3.6.1 Air Compressors (MCP 1, MCP-2, MCP-3)

Electric locos need compressed at a pressure ranging from 6 kg/cm2 to 10 kg/cm2.

Compressed air is used for the loco's own air brake system as also for the train brakes,

for raising the pantograph, for operating the power switchgear inside the loco such as the

power contactors, change-over switches, windscreen wipers, sanders, etc.

This compressed air is obtained by providing three air compressors, each having a

capacity to pump 1000 litres of air per minute. However depending on the current

requirement, more than two compressors are rarely needed.

3.6.2 Vacuum Pumps (MPV 1 & 2)

In locos equipped to haul vacuum braked trains, two vacuum pumps are also provided of

which at least one is running in normal service and sometimes both may have to be run

if train brakes are required to be released in a hurry.

3.6.3 Dynamic Braking resistance Cooling Blower (MVRF)

In locos equipped with internal dynamic braking resistances, MVRF blower is provided

for cooling the resistances during braking. While all the Auxiliary machines run on the

power supply provided by the Arno convertor / Static Convertor / Motor-Alternator set,

the MVRF blower runs off the supply derived from the output of the Traction Motor

itself and is connected in parallel to the Dynamic Braking Resistances.

3.6.4 Main Starting Resistance Cooling Blowers (MVMSR)

These blowers(four in number)are provided in WCAM-1, WCAM-2, WCAM-3 locos

and are used during DC line working to cool the Main Starting Resistances(MSR). The

MSR is used for regulating the voltage supplied to the Traction Motors during DC line

working and carry the whole current of the traction motors which results in a lot of heat

generation which must be continously dissipated. The working of the MVMSR's is also

proved by respective sensing relays(QVMSR's) of the diaphragm type which in turn are

interlocked with the relay Q-118

3.7 Power supply

Depending on the locomotive, power for the auxiliary machines is obtained through

three different methods. A separate power supply arrangement is needed because the

motors require three phase supply while the OHE supply is of the single phase type. So

the main requirement of the power supply for the auxiliary machines is for a device

which can convert single phase AC into three phase AC. It becomes a little more

complicated for the dual power locomotives such as the WCAM-1, WCAM-2, WCAM-

3.

The three main types of equipments used to supply power to the auxiliaries are discussed

below.

3.7.1 Arno Convertor

This is a rotary convertor which has a combined set of windings and is used to convert

the single phase supply from the Tertiary winding of the Loco transformer to Three-

Phase AC which is fit for use by the various Auxiliary machines in the loco.

Arno Converter

Schematic diagram of Arno Convertor circuit

The Arno is basically a split-phase induction motor with an additional winding on the

stator for the generating phase. In an induction motor the rotating field of the stator

creates a corresponding field in the rotor squirrel cage too which causes the rotor to start

rotating at "slip" speed which is slightly less than the speed at which the stator field is

rotating. However, this rotating field of the rotor is additionally utilized in the arno to

create power in the generating phase winding which gives the three phase output of the

arno convertor. In the stator winding of the arno, the motoring phases carry the load as

well supply currents of the arno in opposite direction which causes a net reduction in the

actual current carried by the windings in the stator but the generating phase carries only

the load current which causes a voltage drop in the generating phase. To counteract this,

up to 20% more turns are provided in the generating phase winding.

3.7.1.1 Precautions during arno starting

The Arno starts as a split-phase induction motor by inserting a resistance momentarily in

the generating phase winding as shown in the diagram above. This starting resistance

must be removed as the rotor approaches 90% of its normal speed. If this resistance is

left in the circuit, it can cause heating of the generating phase winding and excessive

vibrations. If the starting resistance is removed prematurely it can take longer for the

arno to reach synchronous speed. Hence, to maintain proper timing two methods could

be employed-either measure the speed of the arno by attaching a tacho-generator or

measure the output voltage of the generating phase.

The voltage measurement method has been found to be more effective and is used in this

system. The voltage between the generating phase and the neutral of the arno convertor

remains at a low value till just before the arno reaches its synchronous speed when it

reaches its full value and is measured by the relay named QCVAR. It picks up when the

voltage rises to near maximum value. The energisation of the QCVAR causes the

starting contactor C-118 to open which disconnects the starting resistance. The normally

open (NO) contacts of the QCVAR are also interlocked with the Q-118 relay. This

interlock is used to ensure that if the QCVAR fails to operate within 5 seconds, the Q-

118 interlock trips the DJ. A bypass switch named HQCVAR is also provided which can

be used to bypass the HQCVAR relay in the Q-118 branch so that DJ tripping does not

occur but in such a case the Arno must be monitored continuously to ensure that its not

overheating.

3.7.2 Static Invertor

The Arno convertor suffers from various disadvantages chief of which is output voltage

imbalance which can cause heating up of the auxiliary motors, varying output voltage

because of the variations in OHE voltage, problems related to starting of the Arno, etc.

To overcome these shortcomings and to improve loco reliability, the Indian Railways

have started providing Static Invertor power supply for auxiliary machines in

locomotives.

The Static Invertor comprises a force commutated rectifier, a DC link and an Invertor

which is usually composed of six IGBT switches.

The Static Invertor broadly works in the following manner:

The supply from the transformer tertiary winding is fed into the rectifier of the Invertor

which is force commutated and is usually composed of IGBTs. The rectified supply is

fed into the DC link which is a large capacitor and is charged by the DC supply. The DC

link also has an inductor to suppress the AC ripple left over from the rectification cycle

and harmonics generated by the invertor. Additionally the DC link maintains the supply

to the invertor in case of temporary supply failure and also absorbs transient voltages

generated during switching heavy loads. In some models if the Static Invertor, an IGBT

type switch is provided which is used to switch the DC link in and out of the circuit as

per requirement.

The DC from the rectifier/DC link is converted into three phase AC by the Invertor

module by switching the IGBTs in proper sequence which creates a near sine wave AC

displaced by 120 degrees. Voltage control is achieved by the Pulse Width Control

(PWM) method. This ensures that the output voltage of the Static Invertor is near

constant irrespective of the input voltage from the transformer.

Apart from improving the reliability of the power supply system, one of the most

important advantages of the Static Invertor is that it has considerably reduced Auxiliary

Motor burnouts due drastic improvement in the power quality in terms of voltage.

Additionally the Static Invertor also detects earth faults, single phasing and overloading

hence these functions are no longer needed to be monitored by external devices.

An electronic control system is provided which monitors the complete functioning of the

Static Invertor. The control system gives the gate firing impulses to the various IGBTs

and also controls the phase angle of the firing pulse to ensure proper phase sequencing.

In addition it monitors the Static Invertor for internal and external faults.

3.7.3 Motor-Alternator Set (used only in the WCAM-1 and the WCG-2

locos)

Motor-alternator set provided in WCAM-1 locos. The MA set is the green machine to

the right. The silver box to the top left is the FRG (Frequency Regulator). Click for a

larger view.

The MA set is used to generate power for the Auxiliary machines in both the AC as well

as DC sections because the Arno cannot run in DC line supply. The MA set comprises of

a DC motor coupled to an AC alternator by a mechanical coupling. When the loco is

under AC line supply the DC motor of the MA Set is fed by the tertiary winding of the

transformer via an auxiliary rectifier known as RSI-3. While running in DC line sections

the DC motor of the MA Set is supplied directly by the OHE line supply. The switching

between the AC and DC modes is determined automatically by the position of the Panto

changeover switch ZPT which in turn determines the position of the Change-Over

switches.

A stable AC supply output consists of two main parameters namely the frequency and

the voltage. The frequency of the output supply is directly dependent on the speed at

which the alternator is running and the output voltage is dependent on the field

excitation voltage of the alternator. Generator speed tends to fall as the electrical load on

the generator increases and vice-versa. To keep the speed of the alternator near constant

a frequency regulator is provided which continously monitors the frequency and as per

requirement controls the speed of the alternator by reducing or increasing the field

excitation of the DC motor. A bypass switch for the frequency regulator is also provided

in case the FRG becomes defective.

CHAPTER-4

RESEARCH, DESIGN&DEVELOPMENT

4.1 Development of Electric locomotive with Head On Generation

(HOG) facility

At present, a Power Car equipped with diesel generator capable of generating adequate

power of 3 phase 50 cycle 415 V/ 750 V AC is provided at either end of the train rake to

supply power to End on Generation (EOG) coaches of Rajdhani/Shatabdi Express trains.

This system is not only highly inefficient but also creates noise and environmental

pollution for the passengers and public. In keeping with the worldwide practices of

meeting power supply requirement of coaches in a passenger train by locomotives,

known as Head on Generation (HOG) System, a WAP7 electric locomotive with on

board centralised Universal converter of 2x500 KVA/750 V single phase input, 750 V

single phase/3- phase output capacity has been developed. The locomotive hauling the

train feeds power supply requirement of the complete train having AC/ Non AC coaches

through Overhead Electric Equipment (OHE), transformer and converter in the

locomotive without the need for having individual self-generating equipment in each

coach. Based on the guidelines issued by Railway Board for development of

locomotives with hotel load facilities in their transformers, RDSO has taken action for

the same on different types of electric locomotives namelyWAP4, WAP5 & WAP7 for

hauling coaching trains. On one WAP7 locomotive(30279), 2x500 kVA hotel load

converter has been fitted and commissioned. Two

power cars have been modified and actual commercial service with this locomotive

having HOG system on KalkaShatabdi rake has been introduced in February,2011.In

this system, the hotel load winding of 945 KVA of transformer feeds power to two 500

kVA static converters which convert single phase 750 V supply into 750 V three phase

supply. The three phase supply is transmitted to both the feeder of the existing EOG

train through IV coupler

4.2 HOG System Provided in WAP7 Locomotive

One transformer has already been developed forWAP4 locomotives with hotel load

winding. For WAP5locomotives, an integrated traction cum hotel load convertor is

under development. The main benefits that will accrue with the development of this

system are supply of pollution free and cheaper power from OHE as compared to End on

Generation (EOG) and Self Generating (SG) system, better reliability due to reduced

number of generating equipment, low maintenance requirement, reduced dead weight as

compared to SG and EOG system resulting in improved energy efficiency, elimination

of under slung equipment leading to enhanced safety and facilitating operation of Air

conditioning equipment of coaches even at reduced train speed below 28 kmph.

4.3 Modification in brake rigging arrangement and up gradation of

speed of WAP7 locomotives

Railways had been reporting breakages of brake hanger of TBU/PBU in WAP7

locomotives. It was observed that the breakages were taking place at higher speed due to

higher level of vibration and higher weight of PBU/TBU. Worldwide, PBU/TBU is not

in use on high speed passenger locomotives. The existingTBUarrangement in WAP7

locos can be replaced with brake system similar to WAG7 locos. Similar brake rigging

arrangement has been in use in high speed WDP2 locomotive, which is working at a

maximum speed of 120 km/h and fit to work up to maximum speed of160 km/h.

Feasibility study done by RDSO in this regard revealed that the following modifications

are required to be carried out in the bogie frame ofWAP7:

Removal of existing tubes and brackets from the bogies by oxy-cutting.

Grinding/finishing of the bogie surface.

MIG welding of brackets, studs for mounting brake cylinder and brake levers and

slack adjuster unit.

Removal of existing pneumatic pipelines and relaying of pipelines suitable for

WAG7 brake rigging.

Stress relieving (normalizing) of bogie frame after welding at a maximum

soaking temperature of 600º C.

subjected to oscillation trial for service speed of 140 km/h which has been successfully

completed and the speed certificate for operation of the WAP7 locomotive up to 140

km/h with modified brake rigging arrangement has been issued .

4.4 Development of high horse power locomotives for Heavy Haul

Operation

In order to meet the challenge of ever increasing originating freight

loading, it has been decided to procure 800 nos. new generation

electric locomotive during next 8 years through a new electric

locomotive manufacturing unit being set up under joint venture at

Madhepura, Bihar. RDSO has finalized the specification for the

12000HP high horse power new generation electric locomotive for the

proposed dedicated freight corridor, to be procured from reputed

manufacturers of the state of the art locomotive.

Technical Specification No. RDSO/2006/EL/ SPEC/0044 for 12000 HP , 8 axle

IGBT base three phase drive freight electric locomotive for proposed Dedicated

Freight Corridor has been issued and the same is expected to be ready after

establishment of the new locomotive factory proposed in Madhepura.

RDSO has also finalized the specification for the 9000HP high horse power new

generation electric locomotive for the proposed western corridor, to be procured

from reputed manufacturers of the state of the art locomotives. Technical

Specification for IGBT based three phase drive freight electric locomotive for

proposed western Corridor is under finalization by RDSO.

Locomotives to be made at upcoming Electric Loco Assembly and Ancillary

Unit, Dankuni, West Bengal has been Technical Specification for manufacturing,

assembly and supply of body/shell, IGBT based three phase drive propulsion

system and other equipment of WAG9 and WAP7 Electric prepared and sent to

Railway Board.

4.5 Up gradation of WAP5 Locomotives for Service Speed of 200kmph

As decided in 28th Governing council meeting held in RDSO, this development has

been taken under mission 24. In this regard test trial of WAP5 locomotive along with

LHB coaches on the upgraded track of a Rajdhani route section at test speed of 225

kmph will have to be done.

For increasing service speed of WAP5 loco from 160 kmph to 200 kmph, the

transmission system of the locomotive is required to be changed as per design detail

submitted by M/s BT in the TOT. Rly. Board has approved for manufacturing of two

WAP5 locomotives by CLW with modified transmission system. CLW has been advised

in this regard. PO has been placed on M/s

Henschel for two loco sets of material ,which is expected shortly.

4.6 Development of oil free compressors

RDSO has developed oil free compressors for electric locomotives owing to its

superiority over the conventional lubricated type compressors. The merits of the oil free

compressors include reduced maintenance cost and down time of Locos, eco-friendly

due to oil free air, longer service life of air dryer and other pneumatic

valves/components, low vibration and low noise, reduced start up energy requirement,

low life cycle cost, no fire hazard. Two units of M/s. Knorr-Bremze make (2000 LPM)

have completed field trials. The performance of the oil free compressor was found to be

satisfactory. Further, development & prototype type testing of 1000 LPM ompressors of

M/s. Anesta Iwata Motherson Ltd., Noida & M/s ELGI has also been completed. 02

units of each firm are under field trial.

4.7 Development of Air operated pantograph

RDSO has finalized specification of direct air operated Pantograph & around 40

pantographs of M/s. Schunk Metal &Carbon India are in service. Direct air operated

Pantograph have distinct

advantages of light weight, improved dynamic behaviour, practically maintenance free

operation over the conventional metallic spring operated Pantographs. It has completely

addressed the major reliability problems of breakage of springs, servomotor failures and

jamming of plunger being faced in conventional Pantographs. The direct air operated

Pantograph uses state of art air spring and does away with more failure prone

components such as servo motor and the metallic

spring of the conventional Pantograph. There is provision of Auto dropping device to

protect pantograph from external hitting. Improved dynamic behavior of air operated

Pantograph also results in better current collection.

4.8 Improved cooling arrangement for Electronic cards

There are failures of electronic cards on account of high temperature experienced around

the cards, which results in failure of certain components such as electrolytic capacitors

after 4-5 years of service. RDSO conducted measurement of temperature near cards and

found that temperature in power converter cards rises 15 degree C above ambient as

compared to 9-11

degree C rise in Aux Converter and VCU. The failure of cards is also maximum in

power converter. Following actions have been taken by RDSO to eliminate electronic

cards failures in three phase locomotives due to high temperature. To reduce the

temperature near the cards of power converter, the design of heat exchanger of traction

converter electronics have been modified for better cooling. The manufacturers of

converters have been advised to cut in this type of cooling radiator in their future

production considering its superiority. Also Railways have been advised for retro

fitment of this cooling radiator. For improvement of cooling of electronic cards, a 3 ton

air conditioner has been provided in one loco at GZB shed at machine room blower

outlet on experimental basis. Further extensive trials are planned in 03WAG9 locos at

AQ and 02WAP7 locos at GZB. Another trial with Thermo Electric cooling Module

(TECM) based on the principle of ' Peltier effect' has been tried in one Loco to lower the

temperature rise around the cards. The trial has been successful and has shown a

reduction of 6-8ºC in temperature rise. Further extensive trials are planned in

05WAG9locos at GMO RDSO has identified a paint 'ozo protect RW' which has helped

in reducing the temperature rise by 8-9 degree Celsius during day time but increases the

temperature rise by 6-8 degree Cesius during night time due to non dissipation of heat

through roof. However it has over all benefit of maintaining the temperature below 55

degree Celsius during hot sunny time and less than 50 degree Celsius at other times of

the day. Another paint 'Ozo Protect KR' having reflecting capability but very less

thermal insulation properties has been applied in one loco at Ajni. However

measurements during day

time under Sun are yet to be done due to prolonged monsoon season

4.9 Standardization of maintenance/fitment practices of Equalizer and

Compensating Beam Pins and Cotters inWAG7locomotives

It was observed that different railways are following different practices on the

maintenance/fitment of Equalizer and Compensating Beam Pins and Cotters in WAG7

locomotives. On analysis, it was observed that

this practice was not only non uniform leading to different maintenance practices but

also unsafe.

Accordingly, a workshop was held at ELS/TKD in May, 2010 and after taking into

account, the suggestions of different railways, Special Maintenance Instruction No

DSO/2010/EL/SMI/0264 'Rev O' has been issued to all the railways specifying uniform

maintenance/fitment practices for the above items by the Railways.

4.10 Development of Hall Effect Speed Sensors

Due to poor output pulse and poor reliability ofWeigand speed Sensors, problem of

wheel slipping and poor adhesion is being encountered in field. Active hall effect speed

sensors have been developed and were put on trial on WAG9 locomotive at ELS/GMO

since Jan '08. Field trial results were found to be encouraging, as the tractive effort

fluctuation has significantly reduced from 30-40% to 5-10%. Further, two rounds of

trials of Doppler Radar in conjunction with Hall effect sensors were done at GMO

during Oct/Nov 09 in association with CLW & M/s. ARC/Bangalore and the efficacy of

the system was established. Modification in software /hardware hasbeen done by M/s.

ARC to interface the same with hardware (Doppler radar based sensor) and the same

provided on fewlocomotives for extensive field trials

4.11 Maintenance of Traction motor support plate and Bogie nose to

prevent crack/ breakage of Traction motor support plate (Holder for

Traction motor suspension)

Railways have reported crack/ breakage of TM support plate from lug hole portion in

WAP-7/WAG-9 electric locomotives. On detailed study it was observed that the fillet

radius which is R-8 as per the CLW drawing No. 1209-01-118-002 was very less in

some of the TM supporting plates. The failure of TM support plate in fatigue manner

was due to sharp edges at lug hole portion which had acted as notch for fatigue

initiation. Development of crack and subsequent failure of TM mounting lug is due to

stress concentration at the lug portion due to sudden change of profile. Accordingly a

SPECIAL MAINTENANCE INSTRUCTION No. RDSO/2011/EL/ SMI/0269 (Rev.

m'0') Dated: 18.05.2011 has been issued to all the railways and CLW on the subject with

following instructions:-

One round in situ DPT should be conducted on all TM support plates near lug

portion and TM mounting bogie nose of all WAP-7/ WAG-9 locomotives. DPT

should be conducted on TM support plate lug portion as well as TM bogie nose

of WAP-7/WAG-9 during MOH/IOH/POH schedule.

A modified design of TM support plate to reduce stress concentration at lug

portion is as below:-

The TM support plate should be procured with increased fillet radius (R-12) at

lug portion. For this purpose CLW/CRJ should revise its drawing no.1209-01-

118-002 to increase fillet radius at lug portion from R-8 to R-12. The fillet radius

should be measured in IOH/POH or any other opportunity. TM support plate

should be replaced if fillet radius is found less than 8 mm.

As a precautionary measure 12 mm safety sling should be provided around the

TM plate upper bolt and with bogie transom to prevent falling of Traction motor

on track in case of breakage of TM supporting plate or TM bogie nose inWAG-9.

The sling should be of 12 mm dia. 2300 mm long (For Traction motor no. 1, 2, 5

and 6) and 2700 mm long (For Traction motor no. 3 and 4) as per IS 2762:1982,

6x19 construction with steel core, double crimped at one end and fastened with 3

no. 'galvanized forged wire rope clip' 12 mm on other end.

The safety sling should be provided only on those WAG-9 locomotives where

TM support plate fillet radius is less than 8 mm.After replacement of TM support

plate with fillet radius 8 mm or 12 mm, safety slings need not to be provided.