this ppt will explain the basics about dc generator and also it will briefly explain the applications of dc generator at railway coach and its uses.so its very useful for engineering students

2. THIAGARAJAR COLLEGE OF ENGINEERING
(A Govt. Aided, ISO 9001:2008 Certified, Autonomous Institution Affiliated to
Anna University)
MADURAI – 625 015
Department of Electrical and Electronics Engineering

3. APPLICATION OF DC
GENERATOR
RAILWAY COACH
PRESENTED BY,
V.Rajalakshmi -14E87 T.Naveena -14E80
R.Priyadharshini -14E85 T.Palani Kumar -14E83
S.P.Nandhini -14E79 P.Prakash -14E84
S.Priyanka -14E86 S.Padmanathan -14E82

4. CONTENT:
 OVER VIEW OF DC GENERATOR
 ELECTRICITY IN RAILWAY SYSTEM
 DC GENERATOR IN RAILWAY SYSTEM
 POWER SUPPLY AT RAILWAY SYSTEM
TYPES OF POWER GENERATION IN RAILWAY SYSTEM
 METHODS OF DRIVING THE GENERATOR
APPLICATION
 CONCLUSION

5. DC GENERATOR:
 An dc generator converts mechanical energy to
electrical energy.
 The energy conversion is based on Faradays Laws
of Electromagnetic Induction.
 When conductor moves in a magnetic Field in such
away that it cuts the magnetic lines of flux and emf
is produced
 Emf causes current to flow if the conductor circuit
is closed.

6. BASIC OPERATION OF DC GENERATOR:
 As the loop rotates, the mag. flux through it
changes with time
 This induces an emf and current in the
external circuit.
 The ends of the loop are connected to
split rings that rotate with the loop.
 Connections to the external circuit are made
by stationary brushes in contact with the slip
rings.

7. SIMPLE LOOP GENERATOR:
 Consider a single turn rectangular copper coil is
rotating in a magnetic field.
 The coil occupies different angular positions during
its rotation.
 When the coil is rotated through an angle of 90° the
emf induced in the coil is maximum
 Rotate the coil further by an angle of 180°.The emf
induced in the coil will be zero.
 Rotate the coil further by an angle of 270°.The emf
induced in the coil is maximum in the reverse
direction.
 We conclude that the nature of the emf induced is
alternating.

8. CLASSIFICATION ACCORDING TO EXCITATION:
 Separately excited DC generator
 Self excited DC generator

9. PARTS OF D.C. GENERATOR:
 Yoke
 Pole core and pole shoe
 Field coils
 Armature core
 Armature winding
 Commutator
 Brushes and brush holders
 Bearings

10. YOKE:
 Acts as frame of machine
 Mechanical support
 Low reluctance of mag. Flux
 High reliability
 For small machines: Cast iron
 For large machines: Cast steel

11. ARMATURE:
 The power-producing component of
an dc generator.
 The armature can be on either the
rotor or the stator.
 The windings are placed in slots on
the surface of the armature core
 It consists of steel or soft iron to
provide a good magnetic path, and
laminated to reduce eddy currents.

12. POLE CORES AND POLE SHOES:
 POLE CORE: Carry the field coils
-Rectangular cross section
-laminated to reduce heat loss
-fitted to yoke through bolts
 POLE SHOES: Acts as support to field poles
and spreads out flux

13. COMMUTATOR:
 Hard drawn Cu bar segments
insulated from each other by
mica segments
 Between armature and external
circuit
 Split rings(acts as rectifier)

14. BEARINGS AND BRUSHES:
 Carbon,Carbon graphite,copper are used to collect current
from commutator
 SHAFT AND BEARING:
 SHAFT: Mechanical link between prime mover and
armature
 BEARING: For free rotation

15. ELECTRICITY IN RAILWAY SYSTEM:
 Electrical energy in railways is required for
traction purpose. Coach lighting, fans, mobile
and laptop charger, air conditioning
equipment, pumping, hot plates, bottle
coolers, water boiler, refrigerators, battery
charger for emergency light, radiator motor
and distribution transformer, these loads are
collectively described as hotel load

16. DC GENERATOR IN RAILWAY SYSTEM:
 TRAIN POWER SYSTEM
- Centralized Power Source System
- Distributed Power Source System
 GENERATING EQUIPMENT:
Dc Generator, Belt Tension Device, Control
Device And Battery

17. OUTLINE OF THE GENERATING EQUIPMENT:
 DC GENERATOR:
when the train is
stopped, power supplied to the
load from the battery.
when the train is
running , the dc generator
supplies power to the load at the
same time charges the battery
which was discharged when the
train was stopped to maintain
the battery fully charged state.

18. OUTLINE OF THE GENERATING EQUIPMENT:
 BELT TENSION DEVICE:
The Dc Generator Suspended From The
Under Frame Of The Coach And Driven By The
Flat Belt Axle Pulley
The Tension Of The Belt Is Maintained
Constant With The Help Of Change The Distance
Between Center Of The Pulleys
 CONTROL DEVICE:
- Rectifying Device
- Generator Voltage Regulator
- Lamp Voltage Regulator

19. POWER SUPPLY:
Electric power to railway coach is supplied through.,
 Overhead lines
 DC batteries
 Generators

20. INTERNAL STRUCTURE:

21. OVER HEAD LINE:
 Power supplied to moving trains
trough continuous conductor
running along the track.
 This wire suspended from poles
are called as catenary wire.
 This train picks up the power
from wire through pantograph.

22. DC BATTERIES:
 DC batteries in trains acts like power banks.
 These batteries are charged through the
supply from over head lines and generators
in trains.
 Batteries are used to provide supply in
case of power shortage.
 Lithium batteries are commonly used in
trains.
Li-ion batteries used in trains

23. GENERATORS:
The generators used in railway coach are
basically classified into two
Main generators.
Auxiliary generators.

24. MAIN GENERATORS :
 These generators are used in propulsion of train.
 These generators provides supply to traction motor
in train .
 Hence helpful for the movement of train in initial
stage.
 Commonly DG sets are used as main generators.

25. DG SETS:
 DG sets stands for diesel generator
sets.
 The diesel generator is a
combination of diesel engine with a
electric generator to generate
electric energy.
 This a specific case of engine
generator.
Generator

26. WORKING –DG SETS:
 The fuel (diesel) is fed to the engine.
 When the engine is started it coverts the chemical energy to
mechanical energy(rotating shaft).
 The rotating shaft is coupled with the generator and provides the
required mechanical input to the generator.
 This rotation of shaft in turn rotates the rotor of generator.
 As the rotor rotates emf is induced and electrical energy is taken as
output,
USE:
The electrical energy obtained is mainly used as a supply to traction
motors used in train.

27. DG SET:

28. TYPES OF POWER GENERATION:
 Self generation(SG)
 Mid on generation(MOG)
 End on generation(EOG)
 Head on Generation(HOG)

29. SELF GENERATION:
 DC Generator is mechanically
coupled with the coach wheel.
 Due to residual magnetic field
and variable magnetic flux
,voltage is induced in the
generator.
 The voltage generated is then
sent to charge the dc batteries.

30. SELF GENERATION:
 ADVANTAGES:
• Higher flexibility in rake
formation
• Each coach is self- sufficient in
generation
• Depending on usage , can be
designed for required capacity
 DISADVANTAGES:
• poor efficiency – 57%
• higher weight affects speed
potential- not suited above
110 kmph
• Maintenance of batteries, axle,
pulley- belt as they are
subjected to vibration
continuously.

31. LUCKNOW MAIL HAULED BY DIESEL LOCO
WDP 4 EMPLOYS SELF GENERATION

32. MID ON GENERATION(MOG):
 Supply obtained at 110V
through one power car in the
center having 230kVA Diesel
generator sets.
 Used for trains having
frequent stops.
 Suitable for slow moving
passenger trains.

33. MID ON GENERATION(MOG):
 ADVANTAGES:
• Centralized control in all
coaches.
• Absence of bulk
batteries.
• Reduced maintenance.
 DISADVANTAGE:
• Space constraint since one
coach has to be dedicated for
power generation(power car).

34. END ON GENERATION:
 Employs two power cars at both ends of the
train.
 Power cars fitted with 2x750kVA Diesel
generator sets.
 Supplies electric energy to individual coaches.
 A 24V , 90Ah battery is provided under frame
along with battery charger to provide emergency
lighting in times of power failure.

35. USE OF END ON GENERATION(EOG):
 Mainly used in fully air conditioned trains
Presently this system is followed in
 Rajdhani express
 Sadhapthi
 Duranto
 Garib rath

36. EOG IN DIESEL LOCOMOTIVE HAULED TRAINS:
SHATABDI EXPRESS HAULED BY WDM 3
DIESEL LOCO
DURONTO EXPRESS HAULED BY DIESEL
LOCO

37. POWER CAR OF SHATABDI EXPRESS:

38. END ON GENERATION:
 ADVANTAGES:
• Elimination of bulk batteries
• Reduced dead weight &
maintenance
• High reliability
 DISADVANTAGES:
• Higher fuel cost, noise & smoke
pollution.
• Reduction in commercial space.
• Need for staff to operate &
maintain.

39. MAINTENANCE STAFF INSIDE POWER CAR:

40. HEAD ON GENERATION(HOG):
 In this system, power is provided from the locomotive at
the head of the train.
 Electric locomotives derive power from overhead supply
lines.
 Power produced is 4500kW. The power produced is
supplied to all loads in AC, Non- AC coaches.
 Diesel locomotives use a separate Diesel generator sets
to generate electric power. Diesel locomotives have been
widely replaced by electric locomotives.

41. USES:
 Currently used in Saptagiri express running between Chennai and
Tirupati electrified line, power supply for lighting load of 35kW is
derived from HOG.
 Most widely used in all trains of Northern railways, Central Railways,
South central railways, Southern railways, West Central railways,
Eastern railways.
 Employed in Pandian, Vaigai, Nellai, Intercity express and many other
trains in TN.
 These trains are hauled by WAP 7 electric locomotive capable of
delivering 4500kW power

42. VAIGAI EXPRESS HAULED BY DIESEL
LOCOMOTIVE:

43. TRAINS HAULED BY WAP7 ELECTRIC
LOCOMOTIVE:
Vaigai express Nellai express

44. HEAD ON GENERATION(HOG):
 ADVANTAGES:
• Pollution free
• Cost of power production per
unit is 25% cheaper than EOG &
SG
• More commercial space
available due to elimination of
power cars.
 DISADVANTAGE:
• Power interruption of short
duration.

45. METHODS OF DRIVING THE GENERATOR:
 Carbon shaft arrangement
By mounting generator on mid axle
Belt driven

46. CARBON SHAFT ARRANGEMENT:
 Carbon- shaft driven by gear box mounted on axle
of wheel. Generator mounted on coach under
frame .

47. REASON FOR FAILURE:
 CARBON SHAFT METHOD
FAILED DUE TO THE
FOLLOWING REASONS:
• Breakage of carbon shaft & gear
box.
• Failure of fasteners used for
coupling
• Jamming of carbon shaft
arrangement
Damaged gear box

48. MOUNTING ALTERNATOR ON MID AXLE:
Rotor fitted directly on the axle of the wheel itself. Stator is
in two halves and provided on the axle with the help of split
bearings & held in position with a reaction rod. No belt driven
mechanism.
This method too was unsuccessful. Defects were:
• Damage Of Bearings
• Grease Leakage
• Breakage Of Terminal Box
• Accumulation Of Copper Dust

49. MID AXLE PERMANENT MAGNET ALTERNATOR:

50. BELT DRIVEN PERMANENT MAGNET GENERATOR:
 Reduction in size of rotor due
to use of permanent magnet
instead of field windings.
 Overall reduction in size,
weight possible. It is efficient &
durable.

51. AUXILIARY GENERATORS:
Auxiliary generators are generators that
provide electrical supply to secondary
applications in train such as
Fan
Lighting
Mobile and laptop charging .

52. APPLICATION
CARRIAGE LIGHTING:
 Generator the traditional source for on-board low voltage
supplies. The generator is a DC machine driven by the
diesel engine or, on electric locomotive (train), by a motor
powered from the traction current supply. On a coach, the
generator was often driven directly off an axle (a dynamo),
batteries providing power for lighting when the train was
stationary

53. CARRIAGE FAN:
 400 mm, 300 mm and 200 mm sweep
carriage fans are used on Indian Railways
in SG, MOG, and EOG coaches where the
system voltage could be DC 110 V . As a
passenger amenity item, carriage fans
have to be maintained in such working
condition as to obtain good air flow and
trouble free service for ensuring maximum
passenger satisfaction

54. REGENERATIVE BRAKING:
 During braking, the traction motor connections are altered
to turn them into electrical generators
 The motor fields are connected across the main traction
generator (MG) and the motor armatures are connected
across the load.
 The rolling locomotive or multiple unit wheels turn the
motor armatures, and the motors act as generators.
 The energy generated in generator may be used in two
ways

55. REGENERATIVE BRAKING:
The generated energy is sent back to recharge the batteries.

56. DYNAMIC BRAKING:
The generated energy is sent to the resistor grids in
the roof of the train and is dissipated as heat.

57. BEGIN WITH
END IN MIND