Audit Officers

TECHNICAL DEVELOPMENT (TRACTION) by Y.P.Singh Sr. Professor (Electrical Engg.)

TOPICS • DC to AC Conversion in Mumbai area • 3 Phase Dual Voltage DC/AC EMU • Air Spring Suspension in EMU • Passenger amenities in coaches

DC to AC Conversion in Mumbai area

Traction Power Supply System

ELECTRIFICATION SCENARIO AT A GLANCE •

•

1st Electric Train started on 3rd February, 1925 on ex-Great Indian Peninsula Railway (GIP Railway), (now Central Railway ) from Bombay VT(now CSTM) to Kurla via Harbor line, about 15.00 Km long. Now, as on 31-03-06, the electrified route is 17,450 Km which is about 27.7% of Indian Railways route of about 63,000 Km.

ELECTRIFICATION SCENARIO AT A GLANCE • Passenger Traffic carried out on Electrified route is about 50%. • Goods Traffic carried out on Electrified route is 67%.

TRACTION VOLTAGE SYSTEM • Electric Traction introduced in Mumbai area on 1500 volt DC traction in 1925. • 25 KV AC Traction introduced in 1960 which is now universally adopted in Indian Railways. • 1500 volt DC – 400 route Km.(which is also under conversion to 25 KV AC). • 25 KV AC, single phase 50 Hz – 17,050 route Km

AC vs DC Traction Advantage of 25 KV AC Traction over 1500 V DC Traction • Reduced requirement of copper, steel for supports and cement because foundations are lighter. • Increased substation spacing - 50 to 80 kms as compared to 8 to 10 kms for DC traction. • There is direct application of industrial frequency.

AC vs DC Traction Disadvantage • Because traction is single phase - being fed from 3 phase power transmission lines, steps have to be taken to keep current and voltage unbalance in the grid line within acceptable limits. Supply authorities have to be satisfied about the unbalance likely to be caused in their lines before they agree to supply the power.

MUTP Phase I (under progress) 5th • line between Mahim & Santacruz • Additional pair of line between Borivli & Virar • 5th & 6th line between Kurla & Thane • Optimisation on W.Rlly (including extending EMU services between Virar & Dahanu Road) • Optimisation on C.Rly (including Harbour line) • DC to AC conversion MUTP Phase II (Proposed) • 6th line between Mumbai Central & Borivli • 5th & 6th line between CSTM & Kurla • Additional pair of line between Thane & Kalyan • Bandra-Kurla Rail Link • Extension of Harbour Line between Andheri to Goregaon

Mumbai Suburban Railway Network

Suburban Rail Systems of the World (Passengers Carried per day per route km in ‘000) Mumbai (WR) Mumbai (CR) upto KYN

50

36.7

Tokyo

14.9

Mumbai (CR)

13.9

Seoul

12.9

Chennai

4.7

Buenos Aires

2.6

Johanesburg

1.2

Rio De Jenero

0.6

New York LIRR

0.4 0

5

10

15

20

25

30

35

40

45

Passenger Density (Passengers/RKM /Day)

Source – Paper published titled ”The World Bank, Transport, and the Environment” in journal “Japan Railway & Transport Review, December 1998”

50

WHY DC to AC CONVERSION ?

WHY DC to AC CONVERSION ? •

DC TRACTION HAS REACHED ITS SATURATION LEVEL.

•

INCREASE IN TRAFFIC LEVEL CANNOT BE MET WITH DC TRACTION.

•

DC TRACTION SYSTEM IS PRONE TO FIRE HAZARDS.

•

WASTAGE OF LOCOS AND TIME IN CHANGING OVER.

•

NON-AVAILABILITY OF SPACE FOR BUILDING LARGER NO. OF DC SUB- STATIONS.

•

DIFFICULT FAULT LOCATION AND ISOLATION

COST DETAILS WR estimated cost – 273. 76 crores CR estimated cost – 654.51 crores Department

WR (Rs. In crores)

CR (Rs. In crores)

Electrical

158.29

428.05

Signal & Tele.

99.33

212.59

Civil Engg.

16.05

13.20

Operating

-

TOTAL

273.67

0.67

654.51

Supply arrangement - WR Item No. of Substations Installed Capacity of Substations Substation spacing Switching post

Existing 1500 V DC System

25 KV AC system

21 Nos.

5 Nos.

135 MW

2x21.6 MVA at BSR & BVI 2X 30 MVA at JOS, BA & MX

1 to 5 km

11 to 18 km

--

16 Nos.

MAJOR ACTIVITIES INVOLVED OHE : REPLACEMENT OF STRUCTURE •

EXISTING D.C. OHE STRUCTURE, CONTACT WIRE AND CATENARY WIRE WILL REMAIN SAME IN A.C. TRACTION.

•

WILL REMAIN UNREGULATED AS EXISTING.

•

STRUCTURAL REPLACEMENT APPROX. 30 NOS ONLY.

OHE FITTINGS – •

NEW DESIGNED OHE SUSPENSION ARRANGEMENT.

•

CATENARY SUSPENSION BY STANDARD 9 TON A.C. INSULATOR.

•

CONTACT WIRE HOLDING ARRANGEMENT USING STANDARD BRACKET INSULATOR, BRACKET TUBE, STEADY ARM ETC.

CONVERSION OF EXISTING 1500 V DC TO 25KV AC TRACTION (NEW AND OLD SIDE BY SIDE)

New OHE

Old OHE

3-PHASE DUAL VOLTAGE DC/AC EMUs

Requirement of Dual Voltage Rakes 

Capable of working under 1500 V dc as well as 25kV ac traction system



Dual voltage rakes are required to ensure smooth traffic in V transit phase of conversion from existing 1500 V dc to 25 kV ac traction

Advantages of DC/AC EMUs  Energy Efficient – Saving in energy (25 to 30%) – Saving of approx. Rs. 50 lakhs/year per 12-car rake

 Lower Maintenance Costs – Reduced wear on wheel – Lesser consumption of brake blocks – Lesser maintenance of 3-phase AC induction motor

 Higher Torque and Speed Potential

COMPARATIVE ADVANTAGES OF DC /AC EMU ITEM

DC/EMU

AC-DC EMU

Acceleration (0-40 Kmph)

0.39 m/sec2

0.54 m/sec2

Speed Potential Energy Saving

80 kmph

100 kmph

NIL

Rs 50 Lakhs/12 – Car rake/year

Braking Deceleration.

0.6 m/sec2

0.84 m/sec2

Maintenance

Rs.6 lakhs/Unit/ Year

Rs.4lakhs/Unit/ Year(Expected)

Ratings of major equipments Traction Transformer : 1200 KVA Main Converter/Inverter : 1200 KW/ 1300 KVA Traction Motor : 240 KW Auxiliary Inverter : 70 kVA

FIRST RETROFITTED DUAL VOLTAGE RAKE- READY FOR HISTORIC FLAG-OFF ON 12.6.2001

ROOF DC EMU Roof

DC/AC EMU Roof

Air Suspension in EMU

NEED FOR AIR SUSPENSION  There has been heavy overloading in the EMU coaches due to increasing population in the Metropolitan cities.  As the existing design could not cater to the increased load , there are severe maintenance problems due to breakage of bogie parts.  The existing design characteristics of the coil springs have been stretched to their limits.  Hence, an alternative solution was necessary for ensuring proper suspension to get adequate riding comfort and sustain increased pay load.

Air Spring

General Arrangement

Secondary Suspension

Primary Suspension

Height under Tare and Full Load

COIL SPRING

AIR SUSPENSION

Air Suspension System

Advantages of Air Spring  Air springs are able to maintain constant height irrespective of the load.  Provide improved Reliability and reduced Maintenance.  Enhancement in life expectancy.  Increased riding comfort.

NEED FOR BETTER PRIMARY SUSPENSION Hydro Spring  It is a special development for use as an axle spring in modern rail vehicles.  It acts as a vibration damper and noise muffler.  This allows large vertical deflection, so ensuring a comfortable ride.  To suppress unwanted vibrations, an enclosed hydraulic system is integrated into the conical spring.

Arrangement of Hydro spring fitment on primary suspension

Left Side

Right Side

ADVANTAGES OF HYDRO SPRING Highest safety, greatest comfort and least noise achieved with suspension system based on hydro spring in primary and air spring in secondary. Reliable system. Compact design. Acts as noise muffler to reduce noise. Eliminates additional shock absorbers.

PASSENGER AMENITIES IN COACHES • IN EMU SERVICES – • FORCE VENTILATION TO IMPROVE AIR CIRCULATION • DISPLAY IN COACHES INDICATING DIRECTION OF PLATFORM, APPROACHING STATIONS ETC. • STAINLESS STEEL SITTING FRAMES INSIDE COACH • BETTER ASTHETICS

PASSENGER AMENITIES IN COACHES (CONTD.)

IN MAIN LINE COACHES– • PROVISION OF MOBILE / LAPTOP CHARGING POINT • IMPROVED AIR-CONDITIONING BY PROVISION OF ROOF MOUNTED PACKAGED UNITS (RMPUs) • STATE-OF-ART COACHES IN RAJDHANI / SHATABDI

Thanks