Indian locomotive class WAG-7


The Indian locomotive class WAG-7 is a class of 25 kV AC electric locomotives that was developed in the 1990 by Chittaranjan Locomotive Works for Indian Railways. The model name stands for broad gauge, AC Current, Goods traffic engine, 7th generation. They entered service in 1992. A total of 1970 WAG-7 were built at CLW and BHEL between 1990 to 2015, which made them the most numerous class of mainline electric locomotive till its successor the WAG-9.
The WAG-7 is one of the most successful locomotives of Indian Railways currently serving both freight and passenger trains for over 28 years. Even though with advent of new 3-phase locomotives like WAG-9 and WAG-12, all WAG-7 locomotives except one destroyed in accidents, rest are in service and doing all types of duties.

History

The history of WAG-7 begins in early 1990s with the aim of addressing the shortcomings of the previous WAG-5 class and remove steam locomotives from IR by a target date of 1990. The WAG-5 though were great successes, had became underpowered to meet the growing demands of the Indian Railways. So in early 1990s IR decided to look for a successor the WAG-5 class. The required specification was of a 5000 horsepower locomotive.
Initially, the Indian railways invited tenders to build locomotives to the new specification. The following responses were received:
Each company submitted their prototypes and Indian Railways designated these prototypes as the WAG-7 class and WAG-8 class respectively. Technologically thyristor controlled BHEL WAG-8 was meant to be superior to the WAG-7 which was effectively using tap-changer technology from the 1960s. But due to issues from WAG-8, WAG-7 was selected for mass production.
However, even before the WAG-7 another type of electric locomotive was imported from ASEA in 1988. This locomotive was classified as WAG-6A. However WAG-6As were not selected for mass production because emergence of 3 Phase AC locomotives.

Production History

On 3 August 1992, the first WAG-7 locomotive was inaugurated and christened by Mother Teresa as "SHANTIDAN". After undergoing trials the first 71 of this class were homed at Mughalsarai shed and latter ones at Kanpur. Some units are retrofitted with Static Converters instead of Arno Rotary Converters. STCs are more efficient and require less maintenance. Also, STCs have self diagnostics making troubleshooting easier. WAG-7H is a heavy variant of WAG-7. WAG-7H #28739 has thicker under-frames. WAG-7 #27445 has closed-circuit cameras to monitor the pantograph along with a spotlight to illuminate the same at night, green lamps to exchange signals and a single windscreen on either side. New Katni shed has added Overhead Equipment monitors. Some WAG-7 units have A.C. cabs, SIV, MPFDCS, MPCS, Single arm pantograph, FDCS, Additional COC, Rear-view mirrors, STS, Daulat Ram's Roof-mounted DBRs, SI, Modified ceilings, Bucket seats, Waist-level headlamps, High-reach pantographs, Vigilance Control Device, Wireless Multiple Control, Vertical Dynamic Brake Resistor and microprocessor control. Some units have their MU cables removed. One unit has SCHUNK pantograph. Some units are assembled at Dahod Workshops. Initially WAG-7 had the body-shell similar to WAG-5 but later on all WAG-7 are/were fitted with crew safe shell like the WAP-4 since this provided more space and relatively safer during the impact on a head-on collision. WAG-7H have crew safe shell since beginning. Older WAG-7s have Tiger Face liveries but newer WAG-7s by CLW have yellow stripe on blue livery. All BHEL built WAG-7s have Tiger Face livery. Now, even some older WAG-7s are repainted with yellow stripe on blue livery. It is also the most powerful indigenously designed freight-dedicated locomotive in India.

Technical Specifications

Instead of the ALCO asymmetric trimount Co-Co bogies used in WAG-5 and WAM-4 locomotives, the WAG-7 was given high-adhesion Co-Co bogies. They also had the Hitachi HS15250A seen in present day WCAM-3 and WCAG-1.
Traction Motorsa variant of the standard HS15250 with higher current rating ; Motors built by CLW and BHEL. 6 motors in parallel grouping
Traction Motors Class of Insulation for Armature and FieldC
Traction Motors SuspensionAxle hung and Nose-suspended
Traction Motors Weight
Traction Motors Temperature rise in Armature
Traction Motors Temperature Rise in Field
Traction Motors Temperature rise in Commutator
Traction Motors Coil resistance at of Armature0.0126 ohms
Traction Motors Coil resistance at of Main pole0.0117 ohms
Traction Motors Coil resistance at of Inter pole0.0089 ohms
Traction Motors Continuous rating, 750 V, 900 A, 895 rpm
Traction Motors rating for 1 hour, 750 V, 960 A, 877 rpm
Traction Motors Air gap for Main pole
Traction Motors Air gap for Inter pole
Gear RatioWAG-7 : 65:16 and 18:64 and WAG-7H : 65:16
TransformerCCL India, type CGTT-5400, Primary rating Secondary rating, Tertiary rating 270 V, 32 taps,, Forced Oil cooling, Class A Insulation
RectifiersTwo silicon rectifiers, cell type S18FN350, 64 per bridge, Continuous rating 2700 A / 1050 V per cubicle, Max starting current 3300 A, Forced air cooling
PantographsTwo Stone India type AM-12, including 4 insulators
Bogie drive arrangementGear pinion
Current Ratings1350 A/2min, 1200 A/10min, 960 A/hr, 900 A continuous
Number of sandboxes8
Permanent shunt5%
2 Headlights32 V, 50 W
Lead Acid batteries50 cells, 110 V
Arno Converter Input216 kVA, 415 V, 1 phase 520 A
Arno Converter Out put150 kVA, 415 V, 3 phase 210 A, 1485 rpm
2 TRC-2000 type Compressors by Elgi
2 Compressor Motors, 415 V, 930 rpm
2 Exhauster Motors, 415 V, 970 rpm
2 250 RE type Exhausters by Northey
2 SF India Ltd. Traction Motor Blowers
2 Traction Motor Blower Motors by Siemens415 V,, 50 A, 2920 rpm
2 PFT-59 type Smoothing Reactors by SF India Ltd.
2 Smoothing Reactor Motors, 415 V, 2860 rpm
2 KDBR-1 type Breaking Resistor Blowers by KEC International
Breaking Resistor Blower Motor, 450 V, 76 A DC, 3300 rpm
Brushes gradeEG1055/BG 1165
Brushes type2 split
Brushes size
Brushes Wear limit
2 PHMX-40-6 type Rectifier Blowers by SF India Ltd.
2 Rectifier Blower Motors, 415 V, 4.8A, 2860 rpm
MLBH-60-1-H2 type Coil Cooler Blower by SF India Ltd.
Coil Cooler Blower Motor, 415 V, 45 A, 1450 rpm
Oil Pump by Best & Co. Pvt. Ltd.
Oil Pump Motor, 415 V, 2865 rpm
2 SL 30 type Smoothing Reactors1250 V, 1350 A
Smoothing Reactor Resistance at 0.00344 ohms

Locomotive sheds

Performance

WAG-7 with a gear ratio of 18:64 has the following capacity while hauling BOX wagons :
Level/GradeStart20 Unit?30405060708090100Unit?
Level7500+7500+7500+7500+7500+7500+7500+7500+52363732
1 in 5005859 tonnes?585958595859585957654555380827142003
1 in 2004065406540654065398231252510213515401148
1 in 150346833303272321031452476199517031229916
1 in 10026692294226522342201173614011198861638
1 in 5015121149114011311121879704599419300

WAG-7 with a gear ratio of 18:64 has the following capacity while hauling BOXN wagons :
Level/GradeStart2030405060708090100
Level7500+7500+7500+7500+7500+7500+7500+7500+54043793
1 in 5006836683668366836683660164712390427592021
1 in 2004516443343284209408831982558216615551154
1 in 150379034253361328832122523202617231238920
1 in 10028592340230822722233175914161208866640
1 in 5015751161115211411130885708602420300

WAG-7 with a gear ratio of 65:16 has the following capacity while hauling BOXN wagons :
Level/GradeStart2030405060708090100
Level108157500+7500+7500+7500+7500+7500+730246192785
1 in 5007169716971697169716961925005346523451465
1 in 200473847384738473840853285271519151295820
1 in 150397739603880379532102590215015151020645
1 in 10030022705266526252225180515001055725450
1 in 5017001345133513201120905750515--

WAG-7H has the following capacity while hauling BOX wagons :
Level/GradeStart20304050607080
Level6000+6000+6000+6000+6000+6000+6000+6000+
1 in 5006000+6000+6000+6000+6000+593048353380
1 in 20043504350435043504040321026651885
1 in 15037103710371037053245254521151500
1 in 10028552655262025802195178014851045
1 in 5016601330132013101110895745510

WAG-7H has the following capacity while hauling BOXN wagons :
Level/GradeStart20304050607080
Level6000+6000+6000+6000+6000+6000+6000+6000+
1 in 5006000+6000+6000+6000+6000+6000+50053465
1 in 20048354835483548354085328527151915
1 in 15041353960388037953210259021501515
1 in 10030602705266526252225180515001055
1 in 5017301345133513201120905750515

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