Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

1 INTRODUCTION An electric locomotive is a locomotive powered by electricity from an external source. Sources include overhead lines, third rail, or an on-board electricity storage device such as a battery, flywheel system, or fuel cell. One advantage of electrification is the lack of pollution from the locomotives themselves. Electrification also results in higher performance, lower maintenance costs, and lower energy costs for electric locomotives. Power plants, even if they burn fossil fuels, are far cleaner than mobile sources such as locomotive engines. Also the power for electric locomotives can come from clean and/or renewable sources, including geothermal power, hydroelectric power, nuclear power, solar power, and wind turbines. Electric locomotives are also quiet compared to diesel locomotives since there is no engine and exhaust noise and less mechanical noise. The lack of reciprocating parts means that electric locomotives are easier on the track, reducing track maintenance. Power plant capacity is far greater than what any individual locomotive uses, so electric locomotives can have a higher power output than diesel locomotives and they can produce even higher short-term surge power for fast acceleration. Electric locomotives are ideal for commuter rail service with frequent stops. They are used on high-speed lines, such as ICE in Germany, Acela in the US, Shinkansen in Japan and TGV in France. Electric locomotives are also used on freight routes that have a consistently high traffic volume, or in areas with advanced rail networks. Electric locomotives benefit from the high efficiency of electric motors, often above 90%. Additional efficiency can be gained from regenerative braking, which allows kinetic energy to be recovered during braking to put some power back on the line. Newer electric locomotives use AC motor-inverter drive systems that provide for regenerative braking.

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

2. SUPPLY SYSTEMS FOR ELECTRIC LOCO Indian Railway has adopted 25 KV industrial frequency ( 50 Hz) A.C supply system for traction purposes. The power supplies are derived from 220 KV / 132 KV 3 phase transmission system from the various grids. The basic arrangement constitutes incoming supply to Railway traction sub station at a voltage level of 220 KV / 132 KV , which normally feeds power along the track for 35-40 Km. Adjacent traction sub station are fed from different phases in rotation in order to balance the 3 phase load in its entirety. Neutral sections are provided in between two adjacent sub station to prevent the bridging of different phases while passing the electric locomotive. Level of voltage is reduced to 25 KV for the end use of locomotives by 21.6 MVA signal phase power transformers placed at traction sub stations which are located at every 30-35 Kms distance along the track.

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

3 SINGLE PHASE SUB STATION A) INTRODUCTION The single phase 50 Hz power for the electric traction is obtained from 220/132/110/66 kV Extra High Voltage 3 phase grid system through step down single phase transformers. For this purpose duplicate feeders comprising of only 2 phases are run from the nearest sub-station of the Supply Authority to the traction substation. The 25 kV single phase conventional systems as adopted on Indian Railways have been described in this report. On the secondary side one transformer circuit breaker and one feeder circuit breaker are installed with associated double pole isolator the busbar connections being such that full flexibility of operation is assured. The traction substation is designed for remote operation. The facilities exist to change over from one feeder to the other by means of isolator/bus coupler. One end of the secondary winding of the transformer is solidly earthed at the substation and is connected to track/return feeder through buried rail.

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

B) TRACTION TRANSFORMER The traction transformer is a single phase transformer rated as under. Range Available :

5, 10, 25 & 50 KVA 25 KV I 240V, 50 Hz. Single phase, oil filled

Design:

According to IS & RDSO specifications.

RDSO Spec No.:

ETI/PSI/15(08/2003)

Approval Agency:

RDSO, CORE

Type Tested:

At CPRI & ERDA

Used at: 220/25 KV, 132/25 KV, 110/25 KV & 66/25 KV Railway Traction Substations, Switching stations, and other outdoor locations. The ATs are suitable for pole mounting along with the Railway Track for supply of power to electric signaling and or sub station/switching station loads.

C) CIRCUIT BREAKER The circuit breaker is a device which breaks the circuit automatic under faulty condition and protects the substation equipment. The following types of circuit breakers and interrupters are now in use for traction substation: Circuit Breakers a) 220/132/110/66 kV, Double pole: SF6 type b) 25 kV Single Pole - SF6 type Vacuum type c) Interrupters - SF6 Vacuum type

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

D) ISOLATOR The isolator is a switch which used for isolate the circuit during maintenance and fault condition. It always operates at noload condition.

Single & Double Pole 25 KV Isolators Range Available:

1250 Amp., 1600 Amp & 3150 Amp., 33 KV Class

Design:

As per latest IS & ROSO specifications.

ROSO spec:

ETI/OHE/16(01/94) with slip no. 1 (June2000)

Approval agency:

RDSO & CORE

Type Test: CPRI & ERDA, Vadodra. Used At : Section and paralleling post & sub sectioning & paralleling post, Feeding post & Traction sub-station

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

4 OVERHEAD EQUIPMENTS

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

A) UNINSULATED OVERLAP In this type of overlap the distance between two conductors is kept 200 mm and the conductors are permanently connected by jumpers to have electrical continuity.

B) INSULATED OVERLAP In this case, the two OHE conductors are kept apart at a distance of 500 mm. The electrical continuity at the insulated overlap is bridged by Interrupters or Isolating Switches except at Neutral Section (SP).

C) NEUTRAL SECTION To separate OHE of two adjoining feed posts. A short neutral section (PTFE) type is provided opposite the Traction Sub Station to avoid the need of lowering the pantograph during extended feed conditions.

D) SECTION INSULATOR Section Insulators are provided to insulate the OHE of one track and another track, such as at turn outs & cross over, and to separate secondary tracks and sidings from the main line or other sidings.

E) CONTACT WIRE HEIGHT i) Over Line Structure to permit C class ODC - 4.92 M ii) Electric Loco Shed and Inspection Pits - 5.80 M iii) Level Crossing - 5.50 M iv) Unregulated OHE Temperature 4°C to 65°C - 5.75 M Temperature 15°C to 65°C - 5.65 M v) Regulated OHE with 50 mm Sag - 5.55 M vi) Regulated OHE with 100 mm Sag - 5.60 M vii) Height of the Rail Gauge at level crossing - 4.67 M

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

5. CURRENT COLLECTOR FOR LOCO A) TROLLEY COLLECTOR A trolley pole is not "attached" to the overhead wire. The pole sits atop a sprung base on the roof of the vehicle, with springs providing the pressure to keep the trolley wheel or shoe in contact with the wire. If the pole is made of wood, a cable brings the electrical current down to the vehicle. A metal pole may use such a cable, or may itself be electrically "live", requiring the base to be insulated from the vehicle body. Trolley poles are usually raised and lowered manually by a rope from the back of the vehicle. The rope feeds into a spring reel mechanism, called a trolley catcher or "trolley retriever".

B) BOW COLLECTOR The bow collector is also employed for collecting the current with tramways. The bow collector consist of light metal strip or bow 0.6 or 0.9 meter wide pressing against the trolley wire and attached to frame work mounted on the roof of loco.

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

C) PANTOGRAPH COLLECTOR The pantograph is implied in railways for collection of current where the operating speed is as high as 100 or 130 kmph and the current to be collected are as large as 2000 or 3000 amperes. Pantographs are mounted on the roof of the vehicle and usually carry a sliding shoe for contact with the overhead trolley wire.

These consist of a jointed frame usually of a steel tubing. The contact shoes are usually about 1.2 meters long. There may be a single shoe or two shoes on each pantograph. The shoes may be straight throughout their lengths or cambered slightly or may be in the form of an auxiliary bow. Material used for pantograph is often steed with sometimes, wearing plates of copper or bronze inserted. The pressure varies from 5 to 15 kg. The pantograph is raised or lowered from the driver cab by one of the following methods or with some modification of it. i) ii) iii)

Air raised, gravity lowered. Air raised, spring lowered, Spring raised, air lowered.

The pantograph should be such construction that they maintain continues contact with a overhead wire at reasonably constant pressure at any height. They must be light enough in order to follow the overhead wire as it changes height above the rails to pass under overhead crossing etc., with minimum inertia effects even at high speeds they must be sufficiently strong and rigid to resist air pressures both head on, due to speed of train, and transverse, due to wind; also they must resist stresses due to the sway of the locomotive at high speeds and oo some extent, stresses due to blows from the overhead system at deflectors or turnouts etc. and from striking birds. If, however, there is a serious trouble on the overhead system, the pantograph must be sufficiently pliable so that it will be damaged rather than pulling down the overhead structure. The above arrangement has the following advantages over other types of collectors. i) ii)

It can be operate in either direction of motion. There is no risk of leaving wire junction etc.

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

iii) iv)

The erection of the overhead network is very simple due to absence of points and grooved crossing required for bows. Its height can be varied from the drivers cabin by carrying out simple operations.

6 TYPES OF ELECTRIC LOCO A. CONVENTIONAL LOCO

 WAP 1

 WAP 4

 WAG 5

 WAG 7

B. 3 PHASE LOCO

 WAP 5

 WAP 7

 WAG 9

7 CATEGORY OF ELECTRIC LOCO  Passenger train loco  Goods train loco

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

8 CODING OF LOCO What is the coding of loco signify?     

W=WIDE A=A.C. G=GOODS P=PASSENGER M=MIXED (GOODS+PASSENGER)

Numbers of rolling stock in Ahmedabad shed Total loco 14    

WAP 1 = 4 WAP 4= 4 WAG 5 = 5 WAG 7 = 1

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

9 LAYOUT OF LOCO

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

10 LOCOMOTIVE DEATIL AND SPECIFICATION A) WAP 1

WAP–1 Built by CLW to RDSO specifications. First in the dedicated electric passenger loco series. Production began in 1980 and the locos were at first used solely for the Howrah-Delhi Rajdhani. A single WAP1 (#22001) was all that was needed to haul the 18-coach Rajdhani at a max. speed of 120 km/h. and an average speed of around 82km/h. Continuous power 3760hp; starting TE 22.2t, continuous TE 13.8t. Loco weight is 112.8t.

The original WAP-1 locos were modified and regeared versions of the WAM-4, originally classified WAM-4R. Rated max. speed is 130km/h (some documents suggest 140km/h). Some (5?) with Flexicoil Mark II bogies were classified WAP-1 FM II and later WAP-3. Two WAP-1 units were also converted to WAP-6. [10/02] One of them, #22212, the first prototype WAP-6, was then converted to a WAP-4 and was based at Jhansi (now [8/03] at Mughalsarai).

Many remaining WAP-1's are being converted to WAP-4's by a complete retrofit including new traction motors, new transformers, etc. These upgrades do not result in the 'R' suffix in the road number that is typical for rebuilt locos. Ghaziabad shed locos are currently [1/05] the only ones not scheduled for such upgrades and are expected to remain as 'pure' WAP-1 units. The WAP1E has only air brakes. Earlier WAP-1's had loco air brakes and vacuum train brakes but were retrofitted for dual train brakes. Motors are grouped in 2S-3P combination and weak field operation is available. Elgi compressors, Northey exhausters, S F India blowers. The locos were originally not designed for MU operation but were later modified to allow MU'ing.

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

WAP 1

Manufacturers Traction Motors

Gear Ratio Transformer Rectifiers

Axle load Bogies Pantographs Current Ratings

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CLW Alstom/CLW - TAO 659 (575kW (770hp), 750V, 1095 rpm) Axle-hung, nose-suspended, force-ventilated. 58:21 BHEL type HETT-3900, 3900 kVA. 32 taps. Two silicon rectifiers, with S18FN35 cells (by Hind Rectifier) with 64 cells per unit. 2700A/1050V. 18.8t. Co-Co Flexicoil (cast steel bogies); primary and secondary wheel springs with bolsters Two Faiveley AM-12. 900A/10min

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

B) WAP 4

This 5000 HP locomotive was evolved to meet the requirement of hauling longer trains of 24 coaches at higher speed up to 130 kmph over Indian railways. This loco is presently hauling important high-speed trains on Indian Railways. These are six axles loco with axle and nose suspended drive. 5000 HP 25 KV AC WAP 4 Passenger Electric Locomotive.

Need :Due to advanced mechanical design especially those of bogies, the locomotive has low unsprung masses and is truly track friendly. Presently WAP-5 is the only passenger locomotive with fully suspended drive. Anti-collision posts give locomotive superior crash worthiness. The fleet of WAP-5 class locomotives is now being geared up for the proposed 150 kmph services Salient Details :-

system Class of Loco Track Gauge Axle arrangement Brake System Total weight Wheel Diameter Length over buffers Panto locked down height Traction Motor type Continuous Power at Wheel Rim Starting Tractive Effort Control System Voltage

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25 KV, AC, 50 Hz. WAP-4 1676 mm (Broad Gauge) Co-Co Air and Rheostatic 112.8 + 1% t.` 1092 mm (New) , 1016 mm (Full worn) 18794 mm 4232.5 mm HS 15250A, DC Series Motor 5000 HP 30.8 t 110 V DC

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

WAP 4 Manufacturers Traction Motors

Gear Ratio Transformer Rectifiers Axle load Bogies Pantographs Current Ratings Tractive Effort

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CLW Hitachi HS15250 (630kW, 750V, 900A. 895rpm. Weight 3500kg). Axle-hung, nosesuspended, force ventilated, taper roller bearings. 23:58 (One loco, #22559, is said to have a 23:59 ratio.) 5400kVA, 32 taps Two silicon rectifiers, (ratings?). 18.8t. Co-Co Flexicoil Mark 1 cast bogies; primary and secondary wheel springs with bolsters Two Stone India (Calcutta) AM-12. 1000A/10min, 900A continuous 30.8t

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

C) WAG 5 WAG–5Introduced in 1984. Power 3850hp (some documents say 3900hp, which may be a later modification), 6-axled (Co-Co). Starting TE 382kN (33500kgf); continuous TE 202kN (20600kgf). Adhesion 29%. A very successful class, and probably the one with the most numbers produced. There are many variants of these, starting with the plain WAG-5. WAG-5A locos have Alsthom motors. Later versions were WAG-5H and variants with Hitachi motors: WAG-5HA by CLW, with high-adhesion bogies, and WAG-5HB built by BHEL to RDSO's specifications. (Note: Lallaguda shed uses the simple code 'WAG-5' for locos that would normally be denoted 'WAG-5HA'.) Newer versions have been spotted: WAG-5HG, WAG-5HR, WAG-5RH (here the 'R' is believed to denote rheostatic braking, but not all WAG-5 class locos that have rheostatic braking use this suffix), WAG-5D, WAG-5P for fast passenger traffic (mail and express trains) with gear ratio 21:85. etc,. WAG-5HE variants are believed to have Hitachi traction motors and only air brakes. The detailed differences among these variants are not precisely known. Specifications for the base WAG-5 model are given below. Some of the variants are known to have different gearing and equipment, and different rated speeds. The original WAG-5 units had a top speed of 80km/h. Many variants have a gear ratio of 21:58, the same as that of the WAM-4 6P, which allows these WAG-5 locos to be used for mixed applications including hauling passenger trains at 100km/h. Auxiliaries are from many sources: typically Elgi compressors, Northey exhausters, and other equipment from S F India, but many variations exist. Speed control by parallel combinations of motors and weak field operation. Air brakes for loco, dual train brakes are original equipment. In the external appearance of WAG-5 locos, it can be seen that locomotives with road numbers up until 23293 have side louvres and round glass windows like the WAM-4 locos showing the legacy of the WAM-4 design. From number 23294 onwards the locos have the newer WAP4/WAG-7 style of louvres, thought to be for better ventilation. More recently WAG-5 locos of all types have been retrofitted with data loggers, flasher lights, train parting alarms, etc.

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

WAG 5 Traction Motors

Gear Ratio

Transformer Rectifiers

Bogies Axle load Max. Haulage Pantographs Current Ratings

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Alstom TAO 659 (575kW, 750V, 1070 rpm) or TAO 656; or Hitachi HS 15250A (See description under WAP-4.) Axle-hung, nosesuspended. Six motors. 62:16 or 62:15 with Alstom motors, some 64:18 (Hitachi motors), many now 58:21 for mixed use. BHEL, type HETT-3900. 3900kVA, 22.5kV, 182A. 32 taps. Silicon rectifiers (two) using 64 S-18FN-350 diodes each from Hind Rectifier. 2700A / 1050V per cubicle. Co-Co cast bogies (Alco asymmetric trimount - shared with WDM-2, WAM-4). 20t 2375t Two Faiveley AM-12 1100A/10min, 750A continuous

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

D) WAG 7 With the ever increasing freight traffic and the need for hauling heavier loads in 1 in 200 grade at increased balancing speeds, CLW went into for the design of an uprated version of WAG-5 locomotive with high capacity transformer, rectifier, traction motor, compressor and other matching associated equipments. These are six axles loco with axle and nose suspended drive. DC series motors, controlled by a tap changer are used in this locomotive. Indian Railway is going to achieve 7,00 million tonnes of traffic, WAG-7 is 5000 HP 25 KV AC WAG-7 Freight Electric Locomotive. the main stay of loco. In the locomotive vehicle market WAG -7 is more economical option and one of the cheapest in the world.

Need :Due to advanced mechanical design especially those of bogies, the locomotive has low unsprung masses and is truly track friendly. Presently WAP-5 is the only passenger locomotive with fully suspended drive. Anti-collision posts give locomotive superior crash worthiness. The fleet of WAP-5 class locomotives is now being geared up for the proposed 150 kmph services

Salient Details :Gauge System Voltage Continuous H. P Max. Speed Starting Tractive Effort Continuous Tractive Effort Wheel Arrangement Weight of loco Type of Bogie Gear Ratio Adhesion Brake System Total weight of locomotive

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1676 mm 25 KV AC 5000 100 kmph 402 KN. (41t) 235 KN (24t) 25KV AC, 50 Hz. Co-Co Fabricated 16: 65 34.5% Dual brake-rheostatic and air. 123 t.

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

WAG 7 Traction Motors

Gear Ratio Transformer Rectifiers

Axle load Bogies

Hauling Capacity Pantographs Current Ratings

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Hitachi HS15250-G (a variant of the standard HS15250 with higher current rating (thicker wire gauge, better insulation); see description under WAP-4.) Motors built by CLW and BHEL. 65:18 CCL India, type CGTT-5400, 5400kVA, 32 taps. Two silicon rectifiers, cell type S18FN350 (from Hind Rectifier), 64 per bridge, 2700A / 1050V per cubicle. 20.5t Alco High-Adhesion bogies, fabricated bogie frame assembly, with unidirectional mounting of traction motors, primary and secondary suspension. 3010t Two Stone India (Calcutta) type AN-12. 1350A/2min, 1200A/10min, 960A/hr, 900A continuous

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

11 MOTOR USED IN ELECTRIC LOCO (DC SERIES MOTOR ) A) HOW MOTOR DRIVES THE AXLE ?

The traditional DC (Direct Current) electric motor driving a train or locomotive is a simple machine consisting of a case containing a fixed electrical part, the stator (called the stator because it is static and comprising what is called the field coils) and a moving electrical part, the rotor (because it rotates) or armature as it is often called. As the rotor turns, it turns a pinion which drives a gearwheel. The gearwheel is shrunk onto the axle and thus drives the wheels as shown in the diagram above. The motion of the motor is created by the interaction of the magnetism caused by the currents flowing the the stator and the rotor. This interaction causes the rotor to turn and provide the drive. The stator and the rotor of the DC motor are connected electrically. The connection consists of fixed, carbon brushes which are spring loaded so that they remain in contact with an extension of the armature called the commutator. In this way, the field coils (the stator) are kept in the circuit with the rotor (the armature and commutator).

B) NOSE SUSPENDED MOTOR The following diagram shows the layout of the traditional DC motor mounted in a bogie as a "nose suspended motor". In electric trains or locomotives, the DC motor was traditionally mounted in the bogie frame supported partially by the axle which it drove and partially by the bogie frame. The motor case was provided with a "nose" which rested on a MARUDHAR ENGINEERING COLLEGE

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

bracket fixed to the transom of the bogie. It was called a "nose suspended motor" (see diagram above) and is still common around the world. Its main disadvantage is that part of the weight rests on the axle and is therefore unstrung. This leads to greater wear on bogie and track. Nowadays, designers try to ensure all the motor weight is sprung by ensuring it is carried entirely by the bogie frame - a frame mounted motor.

C) QUILL DRIVE

This is a simplified diagram of a quill drive. A quill is described in the dictionary as, "the hollow stem of a feather" and "a bobbin or spindle", as well as a "feather" and, alternatively, what a porcupine has on its back. In railway traction terms, a quill drive is where a hollow shaft is placed round the driving axle and the motor drives the quill rather than driving the axle as it does with a nose suspended drive. The quill itself is attached, at one end, to one of the wheels by means of rubber bushed links and, at the other end, to the gearwheel by similar links. The big advantage of such drives is that all the weight of the motor is carried in the bogie frame (so it is a frame mounted motor) instead of it being directly supported by the axle and therefore partially unstrung

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

12 MOTOR RATING OF CONVENTOINAL LOCO HITATCHI TRACTION MOTOR

POWER CONT. SPEED VOLTAGE CURRENT FREQUENCY

850KW 1283 RPM 2180V 270A 65HZ

850KW(MAX) 2584 RPM 2180V 393A 132HZ

WEIGHT

2150KG

CAPACITY VOLTAGE

630KW 750V

RATING EXCITATION

CONT. SERIES

CURRENT

900A

COOLING AIR

80M3/MIN

CONT. RATING

RPM 1090

VOLTS 750

AMPS 840

MAX. VALUES

2500

900

1350

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SHAFT O/P 575KW

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

13 TRANSFORMER RATING OF CONVENTIONAL LOCO WINDING

PRIMARY

SECONDARY

AUXILIARY

KVA

4170

3900

270

VOLTS (NO LOAD )

22500

0-865(TAP 0-32)

389

25000

0-862(TAP 0-29)

432

27500

0-859(TAP 0-26)

476

185.3

2250

694

166.8

2250

625

151.6

2250 a6-a5 and a4-a3

567 a1-a0

TEMP. RISE OIL / WINDING

45°C/55°C

TYPE

HETT 3900

PHASE

SINGLE

FREQUENCY

50 HZ

AMPS

A33-A0

WEIGHT

4170

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

14 NUMBERS OF AUXILLARY MOTORS IN CONVENTIONAL LOCO S.No. 1 2

3

4 5

6 7 8 9

Name Of Auxiliary Motor Traction Motor Blower(MVMT) Transformer Oil Cooling Blower Motor(MVRH) Blower Motor For Rectifier BLOCK Cooling(MVSI) Blower Motor For Reactor Cooling(MVSL) Pump Motor For Transformer Oil Circulation(MPH) Main Compressor Motor(MCP) Auxiliary Compressor Motor(MCPA) Crew Cab Fan ARNO CONVERTER

No. Of Motors In HP Rating Loco 02 35 HP/26 KW 01

30 HP/22 KW

02

4 HP/3 KW

02

2.7 HP/2.2 KW

01

4.3 HP/3.0 KW

02

12.6 HP/ 9.5 KW

01

1 HP/.75 KW

04 01

.04 HP/32 W 1-Ф I/P 150 KVA 3-Ф O/P 120 KVA

15 AUTO EMERGENCY BREAK INTRODUCTION Auto-Emergency Brakes (AEB) refers to a special system of braking employed on some ghat sections with steep gradients, notably the Braganza ghat between Kulem and Castle Rock. With this system, the loco's speed is limited to 30km/h and the brakes are automatically applied if the loco moves faster than that at any time on the AEB section.

PROCEDURE The AEB system is activated by means of a key obtained at the top of the descending grade (at Castle Rock for the Braganza ghat). The key, which is specific to each loco, is engaged and turned in the loco, and then removed and handed to the guard of the train (except for light locos where there is no guard). While the AEB system is activated, the loco cannot run faster than 30km/h; the brakes are applied immediately if the speed rises above that. MARUDHAR ENGINEERING COLLEGE

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Summer Training Report on Electric Traction Indian Railway Ahmedabad Division

When the loco reaches the bottom of the down grade (Kulem at the foothills of the Braganza ghat), the AEB system is deactivated and the key is handed over to the Station Master of the station at the bottom of the ghat section (Kulem). From there onwards, the loco can proceed at normal permissible speeds. The AEB key specific to a loco is handed over to the loco pilot by the Station Master of the station at the bottom (Kulem) when the loco is above to ascend the ghat section.

OPERATION The AEB system depends on a speed sensor attached to the axle generator (tachometer generator) of the locomotive. The speed sensor controls the Emergency Brake Relay (EBR). The EBR gets energized when the speed sensor detects that the loco is moving faster than 30km/h (or other programmed speed limit). When the EBR is energized, two emergency brake valves, EBV1 and EBV2 get activated. The first emergency brake valve EBV1 cuts off pilot air from A9 to C2, with the additional C2 relay then causing the Brake Pipe to exhaust, while the second emergency brake valve EBV2 also exhausts the Brake Pipe pressure and causes application of the brakes.

16 AIR BREAK

In the air brake's simplest form, called the straight air system, compressed air pushes on a piston in a cylinder. The piston is connected through mechanical linkage to brake shoes that can rub on the train wheels, using the resulting friction to slow the train. The mechanical linkage can become quite elaborate, as it evenly distributes force from one pressurized air cylinder to 8 or 12 wheels. The pressurized air comes from an air compressor in the locomotive and is sent from car to car by a train line made up of pipes beneath each car and hoses between cars. The principal

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problem with the straight air braking system is that any separation between hoses and pipes causes loss of air pressure and hence the loss of the force applying the brakes.

17 WHEEL SLIP IN LOCO Wheel slip on locos such as the WAG-5/WAG-7,WAM-4,WCAM-1/2/3, is detected by a relay designated 'QD' which is a current differential relay. It detects the difference in the current flow between two traction motors. If all the traction motors are running at uniform and equal speeds, the armature of the relay remains balanced. However, if any of the axles are slipping, the current to this motor is slightly reduced producing a current imbalance in relay QD which is then triggered. QD gives a repeat to a relay 'Q48' which in turn may activate some automatic wheel-slip reduction procedures as detailed below, depending on the configuration in the particular locomotive. Operation of relay Q48 also lights the LSP (Signal lamp to indicate WheelSlip) on the driver's desk. WAG-5/7,WAM-4,WCAM-1/2/3, etc., have been provided with mainly three methods to minimize wheel slip.

18 ELECTRIC LOCO TAP CHANGER On the Indian Railways, a large number of electric locomotives are in operation today. Many different models of these locos have been manufactured, many of which have now been scrapped. However, many of those models which are still in service such as the WAM-4, WAP-4, WCAM-1, WCAM-2, WCAM-3, WCAG-1, WAG-5, WAG-7, etc., use almost the same electrical setup (excepting the newer 3-phase AC locos such as the WAP-5 and WAG-9). These characteristics are obtained in electric locos on the Indian Railways by the use of the series-wound DC traction motor which has an inherent characteristic of exerting a high torque during its starting phase and a high speed during the running phase when the train resistance is minimal. However in order to have proper speed control over these traction motors the voltage supplied to these motors must be varied. Increasing the voltage to the motor increases its torque and speed and vice-versa. This variation of voltage is obtained by the use of an on-load tap-changer in the locos.

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19 BLOCK DIAGRAM OF CONVENTIONAL LOCO

25 KV SUPPLY TRANSFORMER TAP CHANGER RECTIFIER SMOOTHNING REACTOR TRACTION MOTOR

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POWER CIRCUIT DIAGRAM OF CONVENTIONAL LOCO

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20 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. This is somewhat easier with DC than with AC traction as with the latter the phase and frequency of the generated electricity have to be matched to that of the OHE. On the other hand, regeneration with DC motors adds to their bulk and complexity. The newer AC locos have microprocessor control which helps enormously as the waveform and phase of the regenerated power can be adjusted precisely. The regenerated voltage is in effect the loco presenting a negative load to the OHE system, which manifests itself as a slight rise in the system voltage. This results in a corresponding reduction in energy supplied by the generating units on the grid, and the regenerated energy can, in principle, even go back to the supplying grid and be used elsewhere. The OHE is said to be receptive if it is in a state where the loco can use regenerative braking. If there is no other loco on the section that can absorb the power, and if the substation is not set up to send power back to the supply grid, regeneration results in the OHE voltage rising more than a certain threshold -- this is how the control systems on board the loco can detect the (non-)receptivity of the line. If the line is not receptive the loco has to resort to using frictional or rheostatic braking. Even if the line is receptive, feeding power back to the supply grid may not always be possible, though, because of practical constraints in the design of the substation equipment, reverse flow detection relays in the supply grid (provided as protection in case of a fault in the 132kV supply system), improper phase match by the loco resulting in relays blocking the regenerated power, etc. The regenerated power therefore often gets used just by circulating in the OHE system and thereby getting used by other locomotives in the section. Because of this, regenerative braking bears fruit in busy sections where there are always some live locos. (In other railway systems, e.g., in Japan, although not in India, sometimes the regenerated power is just dissipated using large resistive loads at the substation or elsewhere.) Conversely when the system voltage starts dropping, it is an indication that the locomotive(s) on the section is/are not generating power and are instead consuming power (the normal case) in which case the normal power supply feeds energy back in to the OHE. Apart from saving a fraction of the electricity costs for the railways, regenerative braking in practice also offers the driver finer control over braking a train, and the savings in brake pads and other equipment used in normal frictional braking is also significant. It has been claimed that regnerative braking in busy sections can save up to 10% or more of the electricity costs.

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21 GEAR OF TRACTION MOTOR  SPUR GEAR – CONVENTIONAL LOCO  HELICAL GEAR – 3 PHASE LOCO SPUR GEAR Spur gears or straight-cut gears are the simplest type of gear. They consist of a cylinder or disk, and with the teeth projecting radially, and although they are not straight-sided in form, the edge of each tooth thus is straight and aligned parallel to the axis of rotation. These gears can be meshed together correctly only if they are fitted to parallel axles

HELICAL GEAR Helical gears offer a refinement over spur gears. The leading edges of the teeth are not parallel to the axis of rotation, but are set at an angle. Since the gear is curved, this angling causes the tooth shape to be a segment of a helix. Helical gears can be meshed in a parallel or crossed orientations. The former refers to when the shafts are parallel to each other; this is the most common orientation. In the latter, the shafts are non-parallel. The angled teeth engage more gradually than do spur gear teeth causing them to run more smoothly and quietly. With parallel helical gears, each pair of teeth first make contact at a single point at one side of the gear wheel; a moving curve of contact then grows gradually across the tooth face to a maximum then recedes until the teeth break contact at a single point on the opposite side. In spur gears teeth suddenly meet at a line contact across their entire width causing stress and noise. Spur gears make a characteristic whine at high speeds and can not take as much torque as helical gears. Whereas spur gears are used for low speed applications and those situations where noise control is not a problem, the use of helical gears is indicated when the application involves high speeds, large power transmission, or where noise abatement is important. The speed is considered to be high when the pitch line velocity exceeds 25 m/s. A disadvantage of helical gears is a resultant thrust along the axis of the gear, which needs to be accommodated by appropriate thrust bearings, and a greater degree of sliding friction between the meshing teeth, often addressed with additives in the lubricant .

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22 ENERGIZING A DEAD OR STABLED LOCO Whenever the locomotive is not required for the use, the locomotive is switched off and its pantograph lowered, and it is stabled on a suitable line in dead condition. While energizing such a dead or stabled locomotive, certain precautions are to be followed. These are explained below.

1. Locomotive log book inspection This should be gone through minutely and information if any regarding defects or any special working instructions for the locomotive are to be found out. If the locomotive has been made dead for attention of some defects, etc., the locomotive must not be energized before these defects are dealt with. After the logbook is inspected to satisfaction and it is certain that there is nothing wrong in energizing the locomotive the following procedure is to be followed.

2. Checking of the safety fittings of the locomotive All the safety fittings of the locomotive should be checked. If the locomotive is stabled on the pit, the underframe safety fittings must be checked and must be ensured that all the safety fittings are intact.

3. Up the emergency reservoir pressure and raising the pantograph Building After checking the safety fittings, the battery should be switched 'ON' with HBA switch and baby compressor (MCPA) should be started. During the process RAL cock which connects the emergency reservoir to the air circuit of the locomotive should be closed. When the emergency reservoir pressure builds upto 7 to 8 kg/cm^2. The RAL cock should be opened. After building up the pressure, it must be ensured that locomotive is under the OHE. After this Panto should be raised with the help of ZPT key. A sound of an transient arc or spark will be heard when the pantograph touches the OHE, which gives an indication that the OHE is live. The BL key and MPJ should be fitted in its position.

4. Putting the isolation cocks of brakes in proper position The isolating cocks of the locomotive brake and train brake in the working cab should be in open position and in the rear cab they should be in closed position. This should be ensured before closing DJ.

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5. Inspection of switch board/relay boards 5a. Program switches This board is provided behind cab No 2. All the program switches should be at '1' position. If any of the switches is not in '1' position the reason for the isolation of respective relay or equipment should be ascertained and action taken accordingly. 5b. Condition of Relays The condition of the relay targets should be inspected. No relay target should be in a dropped condition. If the target of any relay is dropped, it should checked for any defects and action taken accordingly.

6. H.T. Compartment Tour A walk-through of the locomotive corridor is necessary for visual inspection of the condition of the H.T. compartment. There should not be any abnormalities like leakage of TFP/GR oil, etc.

7. Closing of DJ Now the DJ of the locomotive can be closed by depressing the BLDJ and then depressing BLRDJ. The DJ will then close and this will result in a change in the voltmeter which should now show a reading of approximately 25kV. The BLCP switch should then be turned ON immediately to start the compressor to build up main reservoir pressure of 8 to 10 kg/cm^2.

8.Testing of locomotive brake After building up the MR pressure and releasing the hand brake of the locomotive (if in applied condition), the locomotive brake must be tested and it should be ensured that the brake power is adequate. Any skids or wheel blocks placed under the wheels of the locomotive, should now be removed.

9. Traction testing of the locomotive After moving the MPJ to the forward and reverse positions, the pilot lamp LSB should now extinguish itself. If it does not extinguish itself even with the MPJ in forward or reverse position, the necessary trouble-shooting procedure has to be followed, such as verifying the reverse and Q 50 relays. Following this, the MPJ should be kept in the forward position and with the help of MP two or three notches should be taken by keeping locomotive brakes applied so that locomotive does not move. As soon as one notch is taken the LSGR lamp should extinguish itself. The same testing should be done by keeping the MPJ in reverse position. MARUDHAR ENGINEERING COLLEGE

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10.Checking of emergency brake After taking two to three notches as above, the vacuum or air pressure should be destroyed by applying the emergency brake. The brake should now be applied on the locomotive and at the same time the notches should come to zero automatically.

11. Checking the work of EEC The ZEMS switch should be kept at the '1' position and the MP on the 'N' position; the pushbutton switch for operation of EEC should now be depressed. The notches should come down one by one with each push of EEC push button.

12. Checking of Headlight, Marker light, Flasher light The working of the headlight, marker lights and flasher light should be checked from both the cabs. After carrying out these checks and inspection the locomotive is ready to be worked.

23 WHEELSET A wheelset is the wheel-axle assembly of a railroad car. The frame assembly beneath each end of a car, railcar or locomotive that holds the wheelsets is called the bogie

CONICAL SHAPE Most wheels have a conical shape of about 1 in 20. The conical shape has the effect of steering the wheelset around curves, so that the flanges rarely come into play. The rails generally slant in at the same rate as the wheel conicity. As the wheels approach a curve, they will tend to follow a straighter path. This causes the wheelset to shift sideways on the track so that the effective diameter of the outer wheels is greater than that of the inner ones. Since the wheels are joined rigidly by the axle, the outer wheels will travel further, causing the train to naturally follow the curve. MARUDHAR ENGINEERING COLLEGE

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24 CONCLUSIONS By attending the 30 days training in electric traction Ahmedabad division western railway I conclude that In this overall training of one month I put my greatest effort to understand & explore more & more about the loco and electric traction. But the loco is such a complex machine which has so many function & components which need so much time to understand. But I try my best to utilize this short span of time to bring out the valuable knowledge about the loco and electric traction.

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25 REFERENCE I develop my this training report on “WESTERN RAILWAY ELECTRIC TRACTION AHMEDABAD DIVISION” by using following books and web sites.  Books  A course in electrical power by J.B. GUPTA  THE DEVELOPMENT OF ELECTRIC TRACTION FOR RAILWAY TRAIN SERVICE. BY EDWARD P. BURCH 

Manual for electric traction

 Web Sites    

www.wikipedia.com www.scribd.com www.irieen.indianrailway.gov.in www.google.com

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