What is WAP7?
The WAP7 is a class of 25 kV AC electric locomotives that was developed in 1999 by Chittaranjan Locomotive Works (CLW) for Indian Railways. The model name stands for broad gauge (W), AC Current (A), Passenger traffic (P) locomotive, 7th generation (7). They entered service in 2000 and have been serving passenger trains for over 23 years.
The WAP7 is a passenger variant of the WAG-9 freight locomotive with a modified gear ratio to pull lighter loads at higher speeds. With an output of 6125HP, it is the most powerful passenger locomotive in the Indian Railways fleet, and the most numerous passenger locomotive in India. The WAP7 is capable of hauling 24 coach trains at speeds 110–140 km/h (68–87 mph).
How was WAP7 developed?
The WAP7 was developed as part of the Indian Railways’ Project Swarn, which aimed to improve the speed, safety and comfort of passenger trains. The project involved upgrading the existing locomotives and coaches, as well as introducing new technologies and designs. The WAP7 was one of the outcomes of this project, along with other locomotives such as WAP5, WAG9 and WAG9H.
The WAP7 was designed by CLW based on the German locomotive class 120, which was also used as the basis for the WAG9. The WAP7 inherited many features from the class 120, such as the three-phase AC traction system, the regenerative braking system, the microprocessor-based control system, and the flexicoil bogies. However, the WAP7 also had some modifications to suit the Indian conditions, such as a higher axle load, a higher gear ratio, a larger pantograph and a modified cab design.
What are the features and benefits of WAP7?
The WAP7 has many features and benefits that make it a star locomotive of Indian Railways. Some of them are:
- It has a high power output of 6125HP, which enables it to haul long and heavy trains at high speeds.
- It has a high starting tractive effort of 322.4 kN (72,500 lbf), which helps it to accelerate quickly and overcome gradients.
- It has a regenerative braking system, which allows it to recover up to 30% of the energy during braking and feed it back to the overhead line. This reduces the wear and tear of the brakes and saves energy costs.
- It has a microprocessor-based control system, which monitors and regulates various parameters such as speed, current, voltage, temperature, etc. It also provides diagnostic and fault detection features for easy maintenance.
- It has a flexicoil bogie design, which provides better stability and ride quality. It also reduces track wear and noise levels.
- It has a dual cab design, which allows it to operate in both directions without reversing. It also has ergonomic features such as air conditioning, fire extinguisher etc.
- It has a sleek and aerodynamic body shape, which reduces air resistance and improves aesthetics.
Head-on Generation (HOG)
A main feature of Majority locomotives of this class is that they use HOG or “Head On Generation” technology, which enables them to supply power to the train from the loco’s pantograph instead of EOG or End on Generation sets. EOG sets are power cars with diesel generators that provide 3-phase 50 Hz 415 V / 750 V AC power to the train. HOG technology eliminates the need for EOG sets, which reduces maintenance and running costs.
Conclusion
The WAP7 is the most powerful and successful passenger locomotive of Indian Railways that can haul 24 coach trains at speeds up to 140 km/h. It has many features and benefits that make it a reliable, efficient and comfortable locomotive for passengers and operators. It has also achieved many milestones and records in its service life, proving its excellence and versatility. The WAP7 is a pride of Indian Railways and a symbol of its progress and innovation.
