MODERN TRENDS IN TRACTION SYSTEM OF INDIAN RAILWAYS

Department of Electrical and Electronics Engineering8th semester, B.E.

BY:-ABHISHEK KUMAR USN:-2SD11EE002

Presenting Seminar On

Subject code:-EE451Date:-09-02-2015

2Contents Introduction Working of traction system in INDIA Modern trends

I. Electrification II. Conversion of 25kv system to 2×25kv system III. Conversion of DC motor to AC motor IV. Modernization of Equipment V. Regenerative brakingVI. Use of SCADA and PLC

Conclusion

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Rail transport in India began in the year 1853 from Bombay to Thane.

It is one of the world's largest railway networks comprising 115,000km of track over a route of 65,436 km and 7,172 stations.

IR operates both long distance and suburban rail systems on a multi-gauge network of broad(5 ft 6 inch), metre(3ft 3 3⁄8 in) and narrow gauges(4 ft 8 1⁄2 in).

Presently IR is working on three system 1500V AC system and 25kv AC system and diesel engine system.

Loco’s are designed by CLW,BHEL,TELCO.

Introduction

4 Considering electric system there are 1500V dc and 25KV ac

sys. The LOCO’s gets electricity supply through an overhead

system of suspended cables known as the catenary or OHE.

Working of traction system in INDIA

5Working contd.

The loco uses a pantograph(a metal structure which can be raised or lowered) to make contact with the OHE cable.

This pantograph collects the current from OHE and than through transformer and other devices it goes to Motor.

there are typically 4 or 6 traction motors in a locomotive.

6 The return path is through body of the loco and wheels to the

track which are electrically grounded. Ground connections are provided from the rails at periodic

intervals.

Working contd.

7I. ElectrificationElectric traction was introduced on 3rd February

1925.Now 60 % of the total lines are electrified.Considering electrical sys Mainly there are two

system presently working in India 1500V dc system25 KV ac system

Latest trends is to convert the whole system into one 25kv system means to convert all the dc system into 25kv ac system.

Advantage of Electrification :-1. Higher acceleration and braking features

for frequent starts and stops (mainly for EMU).

2. Haulage of Heavier Freight Trains and Longer Passenger Trains under Electric Traction.

3. Pollution free atmosphere.4. Regenerative braking.

8Diesel Loco’s block Diagram

9Electric Loco’s block Diagram

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II. Conversion of 25kv system to 2×25kv system

There is 3 possible arrangement. Single system (AC) , Booster Transformer (BT) System , Autotransformer (AT) System / 2 x 25kV System / 'Dual' System.

The first two system is now being upgraded to 2×25 kv system.

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1. Single AC system & Booster Transformer (BT) System:

suffer from voltage drops along the length of the catenary(by 5kv or more).

More no. of substations (placed 35-60km apart along the route). The substations are spaced more closer (down to 10-20km) in areas where there is high load / high traffic.

In booster transfer system extra cost of transformer increases the cost of system.

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ADVANTAGE OF 2×25KV SYSTEM

Improved voltage regulation and reduced transmission line losses.

Increased traction substation spacing.

Improved load factor as number of trains fed per feeding post are more.

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III. Conversion of DC motor to AC motor

Direct current motors with series field windings were the oldest type traction motor.

Problems :-1. speed control is done by tap changer on

transformer or resistance control and later by thyristor

2. high current low voltage design(750 V, 1000A) which calls for expensive large diameter cables.

3. Restricted speed 2500 rpm.4. Low power to weight ratio.5. Need more maintenance(commutator, brush etc.)6. More cost than a ac motor

AC motor :-Now latest trends is to use AC motor(3-phase squeral cage indiction) in place of DC motor where all the problems of dc has

Problem :-speed control N= {where f is frequency and p is no

of pole}Solution is to convert the ac into dc and again

convert the dc into ac so that The microprocessor controller can vary the switching of the thyristors produce AC of a wide range of frequencies and voltages and Various kinds of thyristor devices are used to perform the switching.

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High power to weight ratio

can easily operate at 4000 rpm no restriction of speed as in dc motor( upto 2500rpm).

High voltage and low current 2800 V, 300A. Results heavy reduction in operating current, power cables are much lighter and losses are reduced.

regenerative braking can be used.

robust and require little maintenance.

Advantage of AC motor over DC motor

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IV. Modernization of Equipment

To bring down the maintenance cost and improve the reliability of power supply system,

a. Use of Sf6 circuit breaker

b. Use of dry cast resin transformer

c. 8 wheeler self-propelled OHE inspection cars have also been introduced to improve maintenance.

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a. Use of dry cast resin transformer

The main advantage of this type of transformer over the oil filled ones is that they are practically maintenance free.

The copper in the windings cannot be retrieved from the cast resin and so the risk of theft is eliminated.

There being no oil risk of fire and explosion are also absent.

Dry cast resin transformers are currently under evaluation for their service performance.

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D. Conversion of semaphore signal system in colour LED signal.

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Use of LHB coaches at the place of old ICF coach

Advantages:- Microprocessor enabled ac Light weight high speed Plug point in all

compartment do not get turned over or

flip in case of a collision

ICF rake LHB rake

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V. Regenerative braking

Regenerative braking works on the principle of converting the  kinetic  energy of the locomotive (and train)  back to electricity by using the traction  motors in reverse (as generators) and feeding the electricity back to the OHE. 

The newer AC locos have microprocessor control which helps enormously as the waveform and phase of the regenerated power can be adjusted precisely.

it is operated as a generator during braking and its output is supplied to an electrical load; the transfer of energy to the load provides the braking effect.

It can save 10% or more of the electricity costs if used in busy traffic.

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VI. Use of SCADA and PLC 220 / 132 / 25 kV power supply network for electrification

extending along the track over a zone of about 200/300 km is centrally controlled from the division control center through remote control arrangements.

Supervisory Control and Data Acquisition (SCADA) offers ease of monitoring sensors placed at distances, from one central location.

It consists of two main part RTU(remote terminal unit, RCC(Remote Control Center).

The RCC does the work of a supervisor and controls the activities of a network through RTUs.

Several RTUs are required for interfacing with other elements of a network as a power network is very huge.

The end devices which are to be monitored are interfaced with the RCC through the RTU.

This information is queried by the RCC and the RTU uploads the information when required.

This information that is collected from the RTUs is kept in databases and is displayed through the GUI at RCC.

The RCC configures and controls the RTUs

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SCADA Block digram

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Conclusion

As discussed above all the steps taken by Indian railways for up gradation.

As a result of all above steps IR is been upgrading at a faster rate

specially Electrification of existing un-electrified line is being done to adopt many new technology like regenerative braking, ac loco witch is less maintenance ,rugged.

There are lots of research are going on to upgrade the railway .

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Thank you