26-03-2012, 04:46 PM
Traction Control of Electric Locomotives
traction control-ee.ppt (Size: 151 KB / Downloads: 157)
INTRODUCTION
Driving forward of vehicle is called Traction and the system, which employs this type of mechanism is called Traction system
classified broadly into two groups namely:
(1)non-Electric traction systems
(2)Electric traction systems
Requirements of an Ideal Traction System
High starting pulling effort in order to have rapid acceleration.
Equipment capable of withstanding large temporary overloads for short periods.
The locomotive should be self contained and able to run on any route.
Capability of withstanding voltage fluctuations and temporary interruption of supply.
Parallel running usually more than one motor (two or four motors ) should be possible.
ADVANTAGE OF ELECTRIC TRACTION
Cheapness. It is cheapest method of all other methods of traction.
Cleanliness. It is free from smoke and flue gasses
Maintenance cost. Maintenance and repair cost is about 50% of steam traction system.
Starting time. It can be started without loss of time.
High starting torque. This system uses of d.c. and a.c. series motors which has a very high starting torque.
Braking. In electric traction , regenerative breaking is used which feeds back 40%of the energy.
Saving in high grade coal. No coal is required for electric traction.
DISADVANTAGE OF ELECTRIC TRACTION
Higher initial expenditure.
Failure of supply is a problem.
Additional equipments are required for breaking purposes.
The electrically operated vehicles have to move only on electrified track.
Interference with telegraphs and telephone lines.
DC TRACTION MOTOR
It consists of two parts, a rotating armature and a fixed field.
The fixed field consists of tightly wound coils of wire fitted inside the motor case
The armature is another set of coils wound round a central shaft.
The armature is connected to the field through "brushes" which are spring loaded contacts pressing against an extension of the armature called the commutator.
CONCLUSION
no single motor is ideal for traction purposes. But; DC Series Motors are most suitable for this work
Power Electronics have been resorted to in a major way as in case of thyristor control.
Different types of braking for the traction system was studied.