ELECTRIC TRACTION SYSTEM

PRESENTED BY:

I .TULASI RAMROLL NO.-

07901A0217

Introduction Act of drawing or state of being drawn propulsion of vehicle is called tractions. There are various systems of traction prevailing in our country such as steam engine drive, electric drive. These systems of tractions may be classified broadly into groups namely

1) The traction system which do not involve the use of electricity at any stage and called as non-electric tractions system such as steam engine drive, IC engine drive etc.

2) The tractions system which involves the use of electricity at some stage and called as electric tractions. System such a diesel electric drive, electric drive etc.

Systems of track electrification:

1.Dc system.

2.Single phase ac system.

3.three-phase ac system.

4.Composite system

(a). kando system.

(b). single phase to dc system.

Existing Tractions SystemExisting tractions system uses D.C. motors.

a) The 25 KV over head voltage is step down to 2000 V with the help of step down transformer.

b) Rectifier rectifies this A.C. voltage to D.C. voltage.

c) This rectified D.C. voltage is used to operate the D.C. motors in existing system engine.

Causes favoring the DC motors

a) D.C. series motors are less costly, however for some H.P more efficient and requires less maintenance than A.C. series motor.

b) Rail conductor system of track electrifications which is less costly with D.C. system than with A.C. System

Electric traction motors

General features of traction motors:

Mechanical features

Electrical features

Braking:Generally braking is classified into two types in

the traction. Electrical braking.

PluggingRheostatic or dynamic braking.Regenerative braking.

Mechanical braking.Compressed air brakesVacuum brakesHydraulic brakes

Requirements of braking:

The braking should be simple and reliable in action

The braking should be smooth so as to avoid damage of goods.

Maintenance needs should be minimum.The braking force applied to each axle

should be proportional to axle load so as to obtain uniform deceleration.

Power supply for electric tractionElectric trains in India first introduced in Bombay sub urban services in 1925 and in

madras in 1931. at that time the system adopted was 1500v dc.

In earlier days many of the systems used for electrification of railways in India and other countries such as America, France Hungary etc.

From the reports obtained from French national railways the single phase ac system with 50hz frequency is more advantageous both financial and operation.

In India in 1957 for the first time adopted the system has 25kv, 50hz frequency, single-phase system.

High voltage ac supplyArrangement of power supply in India are as follows:

The power is purchased from the authorities who are responsible for the operation and maintenance of 220/132 transmission lines up to 25 kv outgoing terminals of substations. How ever 25 kv ckt breaker is controlled from remote control center by Tpc.

The 220/132 kv equipment is maintained by the transmission authorities and 25 kv breakers are owned and maintained by the railway authorities.

Current collectors for OHS:In over head system the current collectors are

shown below: trolley collector. bow collector. pantograph collector.

Over head construction in railways

Loco TransformerThis is a main transformer of locomotive. The 25 KV single phase AC power supply of OHE 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.

Traction transformerThere are two traction transformer connected in parallel of same rating for the purpose of reliability the rating of transformer are as follows

Capacity : 25 KV.

Frequency : 50 Hz

taps on HT : 32 taps

cooling :forced oil & air

 

Arno Converter1. Arno converter is a device

which convert single phase AC in to three phase AC.

2. The three phase supply needed for the three phase induction motors which used in blowers, exhausters an oil pumps. To supply three phase power to three phase induction motors arno converter is used.

3. Arno converter is rotating device.

DC link

This is essentially a bank of capacitor and inductor or active filter circuitry to further smooth.

Also to trap harmonics generated by drive converter and traction motors.

Power supply for signalingFor the purpose of signaling and reliable operation the 25 KV is converted to 240 V through auxiliary transformer by tapping 25 KV OHE at the places where needed.

Transmission PathUnder ground telecommunication trunk cable is provided for transmitting the signals from and to the Remote Control Centre (RCC) and the controlled Remote Terminal Units (RTU). Three pairs of conductors (one pair for send one pair for receive and the third as spare) from this cable are made available for remote control operation.

Reference:Utilization of electric power

&Electric Traction

by J.B.Gupta

THANK YOU