2. ACKNOWLEDGMENT
I am very much thankful to the concerning officers and
staff of INDIAN RAILWAY AGRA CANTT for their
valuable guidance and advice, especially to Mr. Pradeep
chhabra without their help I would never have
completed my training. I am also thankful to Sr.
Divisional Electrical Engineer North Central Railways for
allowing me for this training.
3. INTRODUCTION
Indian Railway is the world’s fourth largest commercial, by number of
employees with over million employees. Railways were first introduced
in India in 1853. Indian Railways operates both long distance and
suburban rail system on a multi-gauge network of board meter and
narrow gauges.
Form 20th Dec 2010, the railways had developed a 5 digit numbering
system. This need is required because IR RUNS 10,000 trains daily
5. The 2 x 25KV autotransformer system may be
used on 25 kv lines to reduce energy losses. It
should not be confused with the 50 kv system.
The voltage between the overhead line(3) and
the feeder line (5) is 50 kv but the voltage
between the overhead line (3) and the running
rails (4) remains at 25 kv and this is the voltage
supplied to the train. This system is used by
Indian Railways
6. FEEDER
The feeders that receives the power form CESC, and
the power is step down with the help of step down
transformer and then supplied to various colonies,
piller box, etc. This process is shown with the help of
above connection diagram .
6kv from CESC goes to HT ocb 400A with the hwlp of
HT busbar 400A is divided into two 200A and sent to
two transformer each of 250 kva then sent to various
parts.
7. OIL TYPE TRANSFORMER
Transformer oil or insulating oil is usually a highly-refined mineral oil that is stable
at high temp and has excellent electrical insulating properties. It is used in oil-filled
transformers, circuit breakers. Its function are to Insulate, suppress corona
and arcing, and to serve as a coolant.
The oil helps cool the transformer because it also provides part if the electrical
insulation between internal live parts, transformer oil must remain stable at high
temp for an external radiation through which the oil circulates by natural
convection.
The flash point(min) and pour point(max) are 140 c to -6 c respectively. The
dielectric strength of new untreated oil is MV/m (RMS)and after treatment it
should be>24 MV/m (RMS)
8. Testing and oil quality
Transformer oils are subjects to electrical and mechanical stresses while a transformer is
in operation. In addition there is contamination caused by chemical interaction with
windings and other solid insulation, catalysed by high operating temp. As a result the
original chemical properties of transformer oil change gradually, rendering it ineffective
for its intended purpose after many years. Hence this oil has to be periodically tested to
ascertain its basic electrical properties,
These tests can be divided into
1. Dissolved gas analysis
2. Furan analysis
3. PCB analysis
4. General electrical and physical tests:-
colour and appearance
Breakdown Voltage
Water content
9. TRACTION
In Overhead Electrification System, the supply of electricity is through an
overhead system of suspended cables known as the catenary.
The loco uses a Pantograph, to make contact with the overheat contact
cable and draw electricity from it to power its motors.
10. The return path for the electricity is through the body of
the loco and the wheels to the tracks, which are electrically
grounded.
Conductivity may be reduced in cases of dirt and debris on
the rails.
11. There are 2 types of Electrification system in
Indian railways-
DC System: In DC system with overhead catenary, the basic principle is the
same, with the catenary being supplied electricity at 1.5kv DC. The current
from the catenary goes directly to the motor OR convert the DC supply to
AC internally using inverters or a motor-generator combination which then
drives AC motors.
Single system(AC): The overhead catenary is fed electricity at 25kv
AC(single-phase) from feeding posts which are positioned at frequent
intervals alongside the track.
A Remote Control Centre, has facilities for controlling the power supply to
different sections of the catenaries fed by several substations in the area.
12. VOLTAGE USED FOR ELECTRIC TRACTION IN
INDIA
Voltages used are 1.5kv DC and 25kv AC for mainline trains.
The 1.5kv DC overhead system is used around Bombay.
The Calcutta metro uses 750V DC traction with a third-rail
mechanism for delivering the electricity to the EMUs.
The Calcutta trams use 55V DC with an overhead catenary
system with underground return conductors.
Delhi metro uses 25KV AC overhead traction.
13. NO LOAD TESTING SCHEDULE OF A ASSEMBLED
TRACTION MOTOR
The motor is run at 1500 rpm, if running is smooth the motor is run for 30 min.
The rotation of the motor is changed and run at 1500 rpm for another 30 min.
Steady state temp rise, should motor exceed 35 degree centi.
The speed is increased to 2000 rpm and run up to 15 min.
The speed is increased to about 2725 rpm.
Temp rise in the zone should not exceed 50 to 60 degree centi.
14. APPARATUS USED
PANTOGRAPH
MAIN TRANSFORMER
RECTIFIER
REVERSER
CLR
WINDING CHANGE-OVER SWITCH
BATTERY & BATTERY CHARGER
PROTECTION CIRCUIT AND RELAY
SWITCH GROUP 1& 2
15. PANTOGRAPH CURRENT
TRANSFORMER
MAIN
TRANSFORMER
TAP
CHANGER
SMOOTHING RECTIFIER
REACTOR
ADDITIONAL
SMOOTHING
REACTOR
REVERSER MOTOR
BLOCK DIAGRAM
DISC JUNCTION
