20 Years of WAP-7, The Modern Passenger Traffic Workhorse of the Indian Railways

Exactly two decades ago, on 10th May 2000, a shiny white locomotive, the first of its kind, rolled out of Chittaranjan Locomotive Works in West Bengal. It was numbered 30201 and named Navkiran.

In the early uncertainty over IR’s ability to absorb and indigenize 3 phase technology, few could have expected to WAP-7 would go on to and become the high-speed passenger service workhorse of the Indian Railways.

As of today, there are over 1,090 WAP-7 units in service. They haul everything from the top-tier Tejas, Rajdhani and Shatabdi services, to the low-priority, non-superfast mail/express trains.

Navkiran, first WAP-7 electric loco of 6000 HP was flagged off from CLW on 10th May 2000, exactly 20 yrs ago. The performance of this loco is quite encouraging.

It is also quite encouraging that CLW got certification from the Limca Book of Records for creating World Record by producing 402 locos in FY 2018-19. And it is hoped that CLW will be a torchbearer in electric loco manufacturing over Indian railways and will serve the nation

Praveen Kumar Mishra, General Manager, Chittaranjan Locomotive Works

The WAP-7 is arguably one of the most successful efforts in the creation of a modern locomotive for IR. Designed to be low-maintenance and energy-efficient for IR along with a modern, comfortable and user-friendly environment for the loco pilot, the class also has a sizable fan following among rail enthusiasts in India.

The Birth of the WAP-7

A Transfer of Technology agreement was signed between the Indian Railways and ABB in 1993. With this agreement, IR finally had a mature, modern 3 phase locomotive design platform to work with.

30 units of the WAP-5 and WAG-9 classes were delivered by ABB in Completely Knocked Down/Semi-Knocked Down condition between October 1995 and March 1997. These were assembled at CLW, where the production of this new design was to commence in future.

The WAP-5, with its lightweight high-speed design, had limitations in hauling heavy 24-26 coach mail express trains. Thus, the need for a heavier, more powerful design was felt. This led to an in-house attempt to create a passenger variant of the WAG-9 class freight locomotive.

Several modifications were made, including changes to gear ratios and control software. The result was a locomotive capable of producing more than six thousand horsepower and a top speed of 140 kph.

Evolution of the WAP-7

Once the initial teething issues were overcome, the core design evolved in several ways over two decades.

The GTO (Gate Turn-Off) Thyristor based core of the locomotive was replaced with the advanced and more efficient IGBT (Insulated Gate Bipolar Transistor) technology. Braking equipment was replaced with a more traditional design to make high-speed runs safer.

With transformer upgrades, the WAP-7 was also able to supply hotel load power to the train it was hauling. This technique, called HOG, has eliminated the need to operate noisy end-on-generation (EOG) diesel generator coaches on the train, saving fuel costs.

Among the many other refinements was the modification of control software to allow for push-pull operations. This made it possible to operate a train with one locomotive on each end, doubling the power to weight ratio at one go. Significant performance gains resulted.

The core design has proven so successful that Indian Railways already has bigger upgrades in the works.

The Future of the WAP-7

A high-speed variant of the WAP-7, with the suffix HS, has been subjected to extensive trials and found fit for 160 kph services. With the Mumbai-Delhi and Delhi-Howrah corridors set to be upgraded to 160 kph, locomotives fit for such speeds will become critical.

Also in the works is a massive power upgrade. A 9,000 horsepower variant is under development and is expected to be out for trials soon.

WAP-7 HS loco has successfully passed the trial run at 180 kmph and clearance given for run at 160 kmph over IR. We are also working for upgrading the existing 6000 HP of WAP-7 to 9000 HP and the work in going on.

Praveen Kumar Mishra, General Manager, CLW.

Production of the WAP-7 also continues unabated. Indian Railways plans to manufacture 315 units in 2020-21 and 400 units in 2021-22.

With such production volumes and gradual phasing out of older classes, the WAP-7 will continue to be the dominant passenger loco on the Indian Railways for decades to come.