The document is a summer training report submitted by Sunil Kumar detailing his training from June to July 2015 at the Electric Locomotive Shed in Gomoh, Dhanbad. It includes an acknowledgement, contents listing the topics covered, and sections about the company providing an overview of electric locomotive maintenance. Key topics discussed include the operation of electric locomotives, equipment such as the pantograph and traction motors, and the installation process for carbon brushes.

1. Summer Training Report

2. Electric Locomotive Shed
Gomoh Dhanbad
Summer Training Report
10th
June to 9th
July 2015
Guided By - Submitted By-
Mr. Vinay Sir SUNIL KUMAR

3. ACKNOWLEDGEMENT
I am thankful to the organization"ELECTRICAL LOCO SHED
GOMOH DHANBAD" for providing necessary facility to carry
out my training successfully.
It is our duty to record our sincere thanks and gratitude towards
the institute staff, who helped us in bringing
this project to its present form. The valuableguidance and interest
taken by them has been a motivator and source ofinspiration for
me to carry out the necessary proceedings for the project to
becompleted successfully.
Also, we are highly obliged to the head of our training and
placement cell
who provided us such a great opportunity to do our summer
training in a reputed institute like
"ELECTRIC LOCOMOTIVE SHED DHANBAD".

4. CONTENTS
1- About the company
2- Introduction
3- Operation of Locomotive
4- Different Equipment In Electric
Locomotive
5- Dc Motor Brush Holder
6- Performance Of Carbon Brushes and
Failure of carbon brushes
7- Installation of Carbon Brushes
8- Causes of failure of Commutation
9- Main Cause of Brush Failure
10- Conclusion

5. About The Company
The Electric loco shed, Gomoh, Dhanbad
was established during the year 1965 for homing 11 locomotives.
This shed was commissioned primarily to meet the requirement of
passenger and goods traffic over Indian railways. At present the
shed has been expended suitably to home 176 loco motives for
hauling, passenger and goods traffic.
The shed is responsible for carrying out monthly inspection
schedule viz. IA, IB, IC, I0& ICO in addition to annual and
intermediate overhauling schedules.
Further the unscheduled repairs to electric locos of CNB shed &
other sheds are being done as per requirements of RDSO organizati
on & HQ’s instructions. All modification&specialmaintenance
instructions, approved by RDSO & N.Rly. Hd. Qtr. are also carried
out as per the guide lines being issued from time to time.

6. ELECTRIC LOCO MAINTENANCE SHED
Electric Loco Shed maintains locomotive for utilization in freight
and passenger train. All the miner and major inspection are carried
out in the shed on a regular schedule specified by RDSO (Research
Design Standard Organization). Monthly schedule are done at an
interval of 45 days and major schedule are carried out after 18
months.

7. OPERATION OF LOCOMOTIVE
The electric locomotive basically works at 25 KV, 50Hz supply. The
25KV AC supply is drawn from overhead catenaries wires. The
supply from overhead wires are drawn through a pantograph
inside the loco transformer. This transformer is an
autotransformer from which regulated voltage is taken to a
rectifier block for conversion from AC to DC .It may be worth
mentioning that the final tractive effort is through DC traction
motor hence AC is required to be converted to DC. The DC current
from rectifier block is then filtered to pure DC and then fed to
traction motor.
There are 6 traction motors which works parallel to provide the
attractive effort for hauling the train.
All the operations are controlled through control circuit which
works at 110 volt DC. Various power equipments during operation
gets heated up and hence to cool the same, it is done by various
blowers.
Different Equipments in an Electrical
Locomotive

8. 1) Pantograph
It is pneumatically operated equipment mounted on the roof
for collection of current from overhead wire.
2) Main Transformer
It is an autotransformer which is utilized for drawing various
grades of voltage required for operation of locomotive.
3) Rectifier
This unit consists of rectifier diodes connected in bridge for
conversion of AC current to DC current.
4) Traction Motor
The traction motor is one of the most important equipment
in the locomotive which transmits power to wheels for
moving the trains.
5) Auxiliary Circuit
This Circuit is three phase 415 volts which supplies current to
various three phase induction motors used for driving
blowers for forced air cooling of major equipments like
transformer, rectifier, smoothing reactor and traction motor.
This 3 phase line voltage is supplied by either static converter
or Rotary ARNO Converter.

9. 6) ARNO Converter
Arno converter , is specific-duty machine for conversion of a
single-phase supply into a three-phase supply. While the
electric traction supply is standardized as single-phase A.C.
supply, a three-phase supply is needed on locomotives for
driving certain auxiliary equipments. The function of the Arno
converter is to convert the incoming single-phase supply in to
a three-phase supply for the auxiliaries.
ARNO Converter is of vertical construction and has a flexible
mounting .The machine is of robust mechanical construction
to withstand the several vibrations encountered on
locomotives.
TECHNICAL DATA
Single-phase input Three-phase output
KVA 150 KVA 120
Volts 380 Volts 380
Amps 395 Amps 190
Frame VA-330
Class ’F’
Connection: Star RPM 1490 Cycle 50

10. OPERATIONAL PRINCIPLE
The single-phase supply of 380 volts AC is fed ‘direct’ to the
‘U’ & ‘V’ phases of the Arno converter. Since the ARNO
Converter is connected to single-phase supply, no starting
torque is developed. For starting the ‘ARNO’ split phase
starting method has been employed. The W phase winding is
connected to the supply phase U through a starting resistor
R-118 and starting contactor C-118 for a short duration to
start the Arno. Thus unbalanced three-phase voltage is
impressed to each phase winding of Arno converter and the
starting torque is developed .the Arno Converter picks up
speed within five seconds. After the Arno has gained
sufficient speed, the phase W is opened from the starting
circuit by starting contactor C-118.
The Arno converts the single phase input into 3 phase output
as 380 volt ± 22.5%. The three-phase output of the Arno
converter is connected to the auxiliary motors.

11. 7) Control Circuit
The control circuit is purely 110 volt DC and the most
important network for handling various operational feature
of the locomotive. All the power equipment and auxiliary
circuit equipment are controlled through various switches in
110 volt circuit provided in the driving cab. All the circuit and
equipment in the high voltage power side & auxiliary circuit
equipment and the control circuit is protected against
overloading, short circuiting and earth fault. For this purpose
various relays have been used as protection device so as to
protect the circuit from any mal functioning.
8) Asynchronous Motor
Modern traction motor type using three phase AC electrical
supply and now the favoured design for modern train
traction systems. Can be used on DC and AC electrified
railways with suitable control electronics and on diesel-
electric locomotives.
9) Axle Brush
The means by which the power supply circuit is completed
with the substation once power has been drawn on the
locomotive. Current collected from the overhead line or third
rail is returned via the axle brush and one of the running rails.

12. 10) Battery
All trains are provided with a battery to provide start up
current and for supplying essential circuits, such as
emergency lighting, when the line supply fails. The battery is
usually connected across the DC control supply circuit.
12) Camshaft
Most DC electric traction power circuits use a camshaft to
open or close the contactors controlling the resistances of
the traction motor power circuit. The camshaft is driven by
an electric motor or pneumatic cylinder. The cams on the
shaft are arranged to ensure that the contactors open and
close in the correct sequence. It is controlled by commands
from the driver's cab and regulated by the fall of current in
the motor circuit as each section of resistance is cut out in
steps. The sound of this camshaft stepping can be heard
under many older (pre electronics) trains as they accelerates.
14) Chopper Control
A development in electric traction control which eliminates the
need for power resistors by causing the voltage to the traction
motors to be switched on and off (chopped) very rapidly during
acceleration. It is accomplished by the use of thyristors and will
give up to 20% improvement in efficiency over conventional
resistance control.

13. 15) Circuit Breaker
An electric train is almost always provided with some sort of
circuit breaker to isolate the power supply when there is a fault,
or for maintenance. On AC systems they are usually on the roof
near the pantograph. There are of two types - the air blast circuit
breaker and the vacuum circuit breaker or VCB. The air or vacuum
part is used to extinguish the arc which occurs as the two tips of
the circuit breaker are opened. The VCB is popular in the UK and
the air blast circuit breaker is more often seen on the continent of
Europe.
16) Contactor
Similar to a relay in that it is a remotely operated switch used to
control a higher power local circuit. The difference is that
contactors normally latch or lock closed and have to be opened by
a separate action. A lighting contactor will have two, low voltage
operating coils, one to "set" the contactor closed to switch on the
lights; the other to "trip" off the lights.
17) Converter
Generic term for any solid state electronic system for converting
alternating current to direct current or vice versa. Where an AC
supply has to be converted to DC it is called a rectifier and where
DC is converted to AC it is called an inverter. The word originated
in the US but is now common elsewhere.

14. 18) Cooling Fans
To keep the thyristors and other electronic power systems cool,
the interior of a modern locomotive is equipped with an air
management system, electronically controlled to keep all systems
operating at the correct temperature. The fans are powered by an
auxiliary inverter producing 3-phase AC at about 400 volts.
19) Creep Control
A form of electronically monitored acceleration control used very
effectively on some modern drive systems which permits a certain
degree of wheel slip to develop under maximum power
application. The GM Class 59 diesel-electric locomotive built for
the UK has this system. A locomotive can develop maximum slow
speed tractive effort if its wheels are turning between 5% and
15% faster than actually required by the train speed.
21) Dynamic Braking
A train braking system using the traction motors of the power
vehicle(s) to act as generators which provide the braking effort.
The power generated during braking is dissipated either as heat
through on-board resistors (rheostatic braking) or by return to the
traction supply line (regenerative braking). Most regenerative
systems include on board resistors to allow rheostatic braking if
the traction supply system is not receptive.

15. The choice is automatically selected by the traction control
system. .
22) Grid
Train or locomotive mounted expanded steel resistor used to
absorb excess electrical energy during motor or braking power
control. Often seen on the roofs of diesel electric locomotives
where they are used to dissipate heat during dynamic braking.
23) Ground Relay
An electrical relay provided in diesel and electric traction systems
to protect the equipment against damage from earths and so-
called "grounds".
The result of such a relay operating is usually a shut-down of the
electrical drive. Also sometimes called an Earth Fault Relay.
Electrical Connections
The primary function of the brush involves conducting current. In
many cases the brush holder is also a part of this electrical circuit.
Therefore it is necessary that all electrical connections are of
minimal resistance to provide the best path for current flow from
the main lead connection to the contact surface. Corrosion,
contamination, or electrolytic action over a period of time can
cause dramatic increases in resistance which then requires
cleaning. Careless installation of the brushes or the holders can
lead to loose connections. Any high resistance in the brush circuit

16. will result in excess heat or an undesirable path of current flow and
unequal loading of the brushes.
On fractional horsepower cartridge style brushholders with captive
coil spring type brushes the current should flow from the clip
connector at the bottom of the holder up the brass insert to the cap
on the end of the brush and then down through the shunt to the
carbon. The brushes fail very quickly if the round or eared cap on
the end of the brush does not make proper contact with the brass
holder insert. When this condition exists current will flow directly
from the brass insert to the spring or to the carbon. In either case
there will be extreme heat, loss of brush contact, commutator wear,
and eventually motor failure.
Another problem with larger frame sizes can occur when the
holder mounting is part of the electric circuit. If the holder
mounting surface becomes dirty, corroded, or even painted over
then current will again need to follow another path and thereby
cause problems.
Return to top of page.

17. Summary
The general knowledge and experience in the field on rotating
equipment has been slowly declining for many years. In addition
brushholders have seldom ever received proper attention during
trouble shooting or as part of a maintenance program. Therefore it
is hoped that the above information will be helpful in creating
awareness of the potential problems with brushholders as a very
critical component in the satisfactory performance of carbon
brushes on motors, generators, and other types of sliding contacts.
The important factors to check for proper functioning of the holder
and brush are:
1. Inside holder dimensions
2. Holder spacing
3.Holder angle
4.Holder height
5.Spring force
6. Electrical connections
When there is an opportunity to implement new holders, the use of
the principles mentioned above along with the coordination of the
latest constant pressure holder .

18. Installation Steps
Carbon Brush
1-Disconnect the power to the machine using approvedlock-out
procedures.
2. Remove all old brushesfrom the holders. Make
Noteof any unusualconditions of the brushesincluding roughness orburning
of the contact face,
Polished sides on thecarbon, excess heat on thewires, or frayed shunt
wires. Unusual brush conditionsare indications of the need for and improved
brushdesign or for maintenanceon the machine.
3. Inspect the commutatorfor unusual conditions
for high bars and mica.Make note for required
maintenance.
4. Check the inside holdercavity for dust, dirt, oil,
deposits, carbon buildup,corrosion, or burned areas
and clean as needed.
5. Check the terminal connectionarea and clean, asneeded.
6. Brush holders should besecured to their mount andchecked that none
havebecome loosened or are outof alignment.
7. Measure spring forces to ensure there is consistentcontact force at
therecommended level. Usethe measured force to calculate the spring
pressurefor comparison withrecommended level of 4.0+PSI.
8. Remove the old film fromthe brush tracks, if the newbrushes are made
from a different grade. Dry untreatedcanvas applied witha pressure block or
a rubberabrasive. Seater stone canbe used as an alternative.
However, the remainingdust must be vacuumed or
blown out of the machine.

19. 9. Install new brushes in allholders with attention to theorientation on
angled designs.Ensure that the
brushes can move freely inthe radial direction and thatthere is a relatively
close fitin the tangential and axialdirections.
10. Apply the pressure springto the top of the brush.
11. Pull up on the brush andallow to gently return tocontact with the
commutatoror ring to ensure
there is no binding of thebrush and spring.
12. Connect the terminals. Besure all terminal connections are tight and
secure.
13. Seat the brushes to the contour of the commutatorusing non-metal
bearingsandpaper or garnet paper.Do NOT use emery. Mediumcoarse
grade paper pulledunder the brush face in thedirection of rotation
improvesthe quality of the brush contact surface andspeeds the process.
Thereshould be at least 90% ofthe brush face seated to
the contour of the contactsur face prior to operating
the machine at load. Oncethis level has been
achieved, then the resultingdust in the machine aroundthe brushes, holders,
andcommutator should bevacuumed or blown out.
14. Operate the machine at noload for the final wear-incontour of the
contact surfaces in order to ensurecomplete electrical contactof the
brushes. This procedureallows the brush tomake intimate contact in
itsoperating position in theholder.
15. The machine is ready foruse. The film process onthe contact sur face
can beenhanced with the use of anuntreated hardwood burnishingblock or a
rubber polishingstone. This procedurecan reduce the high frictionand brush
dust developed
during the initial filmforming period.
NOTE: In some cases timeallotment, operating conditions, or performance
issues mayrequire the replacement of lessthan a full set of brusheswithout
normal seating. Then, it is especially important to

20. adhere to step 11 with extendedoperation at no-load. Shortcuts on
procedures forbrush installation will result inexcess electrical damage to
thebrush face and the contact surface.
Causes of Commutation Failure
1- Streaking
2- Threading
3- Bar Edge Burning
4- Grooving
5- Slot Bar Marking
6- Photographing
7- Copper
Streaking
Causes
• Low or unequal springpressure
• Low current loads
• Contaminated atmosphere
• High humidity
• Copper particle pickup fromcommutator
(streaking)

21. THREADING
Causes
• Low or unequal springpressure
• Low current loads
• Contaminated atmosphere
• High humidity
• Uneven current distribution
• Conditions have beenmaintained for a long period
of time and causedcommutator damage
BAR EDGE BURNING
Causes
• Low or unequal springpressure
• Incorrect brush alignment /off neutral

22. • Wrong brush grade
• Sparking caused bycommutation problems
• Incorrect interpole strength
Grooving
Causes
• Low or unequal springpressure
• Contaminated atmosphere
• Low humidity andtemperature
• Abrasive brush grade

23. SLOT BAR MARKING
Causes
• Low or unequal springpressure
• Excess vibration
• Wrong brush grade
• Commutator becomesoverheated and softened
• High Friction

24. Copper Drag
Causes
• Uneven current distributionin armature windings
• Unequal number of windingsin adjacent slots
• Inconsistency in armaturewindings related to numberof coils, slots,
andcommutator bars.

25. Carbon Brush Failure
The most common cause of carbon brush failure is incorrect spring tension.
Oncethe proper force is applied, grade selection can be fine-tuned to ensure
optimumbrush and machine performance. For reference, the chart below
indicates the recommended ranges of spring pressure for various
applications and the methodof calculating spring pressure from the
measured spring force.
Spring Pressure
Industrial D.C Applications 4-6 psi 280-420 g/cm2
WRIM & Sync. Rings 3.5-4.5 psi 240-310 g/cm2
High Speed Turbine Rings
Soft Graphite Grades 2.5-3.5 psi 170-240 g/cm2
Metal Graphite Brushes 4.5-5.5 psi 310-390 g/cm2
FHP Brushes 4-7 psi 280-490 g/cm2
Traction Brushes 5-8 psi 350-560 g/cm2
For brushes with top and bottom angles greater than
25 degrees, add an extra .5-1 psi = 35-70 g/cm2
Spring (P.S.I.) =Measured Force (lbs.)
Pressure Brush Thickness (in.) X BrushWidth (in.)
CONCLUSION
A locomotive is a railwayvehicle that provides the motive power for a train. The
word originates from the Latinloco – "from a place", ablative of locus, "place" +
Medieval Latin motivus, "causing motion", and is a shortened form of the term
locomotive engine,[1]
first used in the early 19th century to distinguish between
mobile and stationary steam engines.
A locomotive has no payload capacity of its own, and its sole purpose is to move
the train along the tracks. In contrast, some trains have self-propelled payload-

26. carrying vehicles. These are not normally considered locomotives, and may be
referred to as multiple units, motor coaches or railcars. The use of these self-
propelled vehicles is increasingly common for passenger trains, but rare for freight.
Vehicles which provide motive power to haul an unpowered train, but are not
generally considered locomotives because they have payload space or are rarely
detached from their trains, are known as power cars.
Traditionally, locomotives pull trains from the front. Increasingly common is push-
pull operation, where a locomotive pulls the train in one direction and pushes it in
the other, and can be controlled from a control cab at the other end of the train.
Like great books, no project is created entirely by an individual. There are many
people involved in this project too and have helped a lot right from the beginning
till the completion of our project. Any bouquets for the merits in this project
should go to our door. Any brickbats we are ready to catch ourselves.
It is with a great sincerity, we convey our heartfull gratitude to our Mr.Mohammad
Israr, Supervisor, Electric Loco Shed, Kanpur, for his excellent guidance, valuable
advice and ample co-operation throughout the training. It is a proud privilege to
have availed of the opportunity of guidance.