On load tap changer In A.C. locomotive transformer & Air blast circuit breaker Introduction Block diagram of A.C. Locomotive Equipment of locomotive & their function Advantages Disadvantages

1. On load tap changer In A.C. locomotive
transformer & Air blast circuit breaker

2. Content
• Introduction
• Block diagram of A.C. Locomotive
• Equipment of locomotive & their function
• Advantages
• Disadvantages

3. Introduction
 Locomotives in India consist
of electric and diesel locomotives.
Locomotives are also
called locos or engines.
 An electric locomotive is
a locomotive powered by electricity
from overhead lines, an on-board
energy storage device such as a
chemical battery or fuel cell.
 Electricity is used to eliminate smoke
and take advantage of the high
efficiency of electric motors.

5. Equipment of locomotive & their function
1) Over head conductor :
 This is the over head conductor running along the that
through which high voltage a.c.(22 to 25 kv) is supplied
from traction substation and fed to the locomotive.

6. 2) Pantograph :
 It is a current collecting device mounted on the
roof of locomotive.
 It collects the required power from over head
conductor & feds to locomotive.

7. 3) Circuit breaker :
 The circuit breaker is a protective device for
locomotive equipments it is mounted on the roof of
locomotive.
 The function of circuit breaker is to make the supply
ON & OFF both in normal & faulty condition.

8. 4) Loco Transformer
 The 25 KV single phase AC power supply of Over
head line is fed to the winding of regulating
transformer through main bushing. The winding is
equally divided into 32 taps. These taps are
connected to tap changer.

9. A tap changer is a device fitted to
power transformers for regulation of the
output voltage to required levels.
 This is normally achieved by changing
the ratios of the transformers on the
system by altering the number of turns in
one winding of the appropriate
transformer.
It regulates motor speed by varying
voltage from input side of the
transformer.
5) On load tap changer :

10. 6) Rectifier :
 It is a rectifying unit which converts a.c. Into d.c.
Voltage required for a.c. series motors.
 Instead of using a bridge rectifier, it is possible to
use a thyrister. A thyrister is a kind of diode such
that it allows current to flow when it receives a
command through a third terminal.

11. 7) Smoothing reactor :
 The smoothing reactor is used to make a.c. ripple
free d.c. available from rectifire and pure d.c. is
given to d.c. series motor better performance.

12. 8) D.C. Motors:
 Two or more number of motors receives filtered
d.c. & gives out required mechanical motive
power which is transmitted to train wheel by direct
or geared drive.
 Train wheel move the train-mass linearly on the
track.

13. Air Blast Circuit Breaker

14.  This operates using high velocity blast of air which
quenches the arc.
 It consists of blast valve , blast tube & contacts.
 Blast valve contains air at high pressure.
 Blast tube carries the air at high pressure & opens
the moving contact attached to spring.
 Air should be kept clean & dry to operate it properly.
Air Blast Circuit Breaker :

15. Advantages
 Lower running cost of locomotives and multiple
units.
 Higher power-to-weight ratio, resulting in,
 Fewer locomotives
 Faster acceleration
 Higher practical limit of power
 Higher limit of speed
 Less noise pollution (quieter operation).
 Lower power loss at higher altitudes.
 Lack of dependence on crude oil as fuel.

16. Disadvantages
 The main disadvantage of electric traction is that
it involves a heavy initial expenditure for the
power supply system.
 Power break down for a short period may
paralyse the whole system.
 Electric traction system is bound only to
electrified routes.
 Significant cost of electrification.
 Increased maintenance cost of the lines.
 Overhead wires further limit the clearance in
tunnels.

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