Chilime–Trishuli 220 kV transmission line comes into operation

The Chilime–Trishuli 220 kV transmission line has officially been commissioned. The 28-kilometer line, which runs from the Chilime Hub Substation in Thambuchet, Amachodingmo Municipality, Rasuwa, to the Trishuli Three B Hub Substation in Pahirebensi, Kispang Municipality, Nuwakot, began operating at 7:30 PM on Wednesday after being charged with electrical power.

Along with the transmission line, the Chilime Hub Substation, constructed as part of the project, was also energized on the same day. This substation includes two 220/132 kV, 160 MVA transformers, totalling 320 MVA capacity, and 132/33 kV power transformers with 50 MVA capacity. The Trishuli Three B Hub Substation, which has a 220 kV capacity, was already in operation before this.

The Chilime–Trishuli transmission line was built to integrate electricity generated by hydropower projects on the Trishuli River and its tributaries into the national grid. The line has the capacity to carry approximately 1,200 megawatts of power.

The project, which cost an estimated NPR 3.62 billion, was funded by the Government of Nepal and the Nepal Electricity Authority (NEA), with additional support from the German Development Bank (KfW) and concessional loans from the European Investment Bank (EIB).

Thark Bahadur Thapa, Director of the High Voltage Grid Department at NEA, stated that with the completion of the transmission line and substations, electricity from hydropower projects in the area can now be integrated into the grid at any time.

Initially, the transmission line will carry electricity from the 111 MW Rasuwagadhi, 42.5 MW Sanchhen, and 14.8 MW Sanchhen Hydropower Projects, all led by Chilime Hydropower. These projects have been completed and are now in the power generation phase. Despite public holidays like Dashain and Tihar, workers and contractors continued their efforts to complete the transmission line on time.

A total of 76 transmission towers have been constructed along the 28-kilometre line. The line stretches from 680 meters to 2,600 meters above sea level. Thirty-three of the towers were built in areas without road access, requiring the construction of new access roads. More than 20 kilometres of access roads were built for the project, with materials transported by helicopter to the remote sites.

Building towers in such a difficult and rugged Himalayan region posed many challenges, including steep cliffs, lack of roads, and the need to carry construction materials like stones, gravel, sand, and tower components on foot or by mule. Additional difficulties included the risk of floods, landslides, use of forest land, local opposition, the COVID-19 pandemic, and the harsh weather conditions typical of the region.

In addition, a 1,235-meter stretch of wire was strung from the northern Gaya Municipality–1 Tiru to Siruchet in the same ward, with the help of drones over the Mailung River (Mailung Crossing).

The transmission line includes a 20-kilometre double-circuit line from Chilime to Mailung and an 8-kilometre multi-circuit line from Mailung to Trishuli Three B Hub. The multi-circuit line is being constructed to connect the electricity generated by the 216 MW Upper Trishuli–1 Hydropower Project, which is being developed by Korean companies. The Upper Trishuli–1 project will cover 60% of the cost of constructing the multi-circuit line.

The contract for the construction of the transmission line and substation was signed in 2017 with the Chinese company Pinggao Group of Companies. The project was officially implemented in the same year.