Indian locomotive class WAP-7


The Indian locomotive class WAP-7 is a class of 25 kV AC electric locomotives that was developed in the 1999 by Chittaranjan Locomotive Works for Indian Railways. The model name stands for broad gauge, AC Current, Passenger traffic engine, 7th generation. They entered service in 2000. A total of 1060 WAP-7 have been built, with more units being built at CLW, Diesel Locomotive Works and Diesel-Loco Modernisation Works.
The WAP-7 is one of the most successful locomotives of Indian Railways serving passenger trains for over 20 years. It is a passenger variant of the WAG 9 freight locomotive with a modified gear ratio to pull lighter loads at higher speeds. It is the most powerful passenger locomotive in the Indian Railways fleet, capable of hauling 24 coach trains at speeds.

History

It is now largely used by Northern Railways, South Central Railways, Central Railways, South East Central Railways, South Eastern Railways, West Central Railways, Eastern Railways, Western Railways, North Central Railways, South Western Railways, Southern Railways, East Central Railways, East Coast Railways etc among other zones. As of June 2020, all of which are fitted with H-type transition couplers which are compatible with both screw coupling and centre-buffer coupling. In February 2017, Diesel Locomotive Works built their first WAP 7 class locomotive.

Performance

With a maximum speed rating of the WAP-7 has the highest acceleration figures while hauling mail/express trains. The WAP-7 can also haul loads of 24-26 passenger coaches. It is the most successful passenger locomotive on the Indian Railways roster after the WAP 4. It was initially used to haul premium train services like the Rajdhani Express, Shatabdi Express and the Duronto Express. As more locomotives were rolled out, the WAP 7 became the official link of several state trains like the Telangana Express, Kerala Express, Paschim Express, Purushottam express, Vikramshila express, Poorva express, Karnataka express and among others. The locomotives have been used as a regular link for many of the Garib Rath express and many Humsafar express services and eventually extended to a significant number of AC Express and Mail/Superfast Express services like Jaipur Superfast Express, Thiruvananthapuram Mail, Mangalore Mail, Bangalore Mail, Sewagram express, Panchavati Express, Vaigai SF express and so on. It is soon to be the most commonly used passenger locomotive. Upgrades are underway to increase power output and maximum speed. The First High Speed version WAP-7 HS loco was launched on 28 February 2019 capable of attaining 160 km/h with overall reduction in weight by 14 tons.
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The WAP-7 locomotive can deliver continuously, with regenerative braking being one of its salient features. Regenerative braking is deployed on down gradients conserving energy to the tune of 30-35 percent. It has an inbuilt microprocessor based fault diagnostic system to make troubleshooting easier.

Head-on Generation (HOG)

A main feature of some locomotives of this class is that they eliminate the need to have separate End on Generation sets or DG sets for supplying power to the train resulting in significant savings on maintenance and running costs. This technology, called HOG or "Head On Generation", transfers electric power from the loco's pantograph to the coaches instead of EOG where a power car equipped with diesel generator capable of generating adequate power of 3-phase 50 Hz 415 V / 750 V AC is provided at either end of the train rake to supply power.

Technical Specifications

Locomotive sheds

Named Locos

On 10 July 2011, Kalka Mail derailed on the Kanpur-Fatehpur line near the Fatehpur railway station, more than 72 persons died and 200 were injured, some critically. The train was hauled by a Ghaziabad-based WAP 7 30221. Malfunction of the undergear of the locomotive may have been a reason. The driver of the Kalka Mail said he saw the engine shaking. A post-accident diagnostic revealed that the first axle of the locomotive registered a jerk and the fourth axle showed loss of contact of the wheel with the track.
On 14 December 2014, the Howrah - New Delhi Poorva Express derailed shortly after leaving Howrah, Kolkata. 11 sleeper coaches and a pantry car of the rake jumped the rails in the incident. Due to the derailment occurring when the train was just skipping Liluah, and the usage of LHB coaches, the accident was contained and no casualties were reported. Like the 2011 Kalka Mail derailment, this accident also involved a Howrah-based WAP 7 locomotive.