132 kV GIS Bay Extension at Kaligandaki 'A' Hydropower Station

Overview

The project was executed for the Nepal Electricity Authority (NEA) under the Kaligandaki-Ridi 132 kV Transmission Line Project to extend the gas-insulated switchgear (GIS) at Kaligandaki 'A' Hydropower Station in Mirmi, Syangja. Awarded under Contract No. KGARD-079/80-01 and signed on 10 March 2023, the scope covered the design, supply, installation, testing and commissioning of two new 145 kV GIS bays together with their cabling, control and protection systems, and integration into the station's existing SCADA. The extension strengthens the substation's switching capacity and provides the bay infrastructure required to connect the Kaligandaki-Ridi 132 kV transmission system. Nepal Electricity Authority issued the Substantial Work Completion Certificate effective 30 March 2026.

Scope & Deliverables

• Supply and installation of a 145 kV GIS two-bay module (type 145 SP-3) with adaptor tank, manufactured by Hyundai Heavy Industries (China) Electric Co. Ltd.
• Supply, laying and termination of 145 kV 800 sq. mm single-core XLPE power cable and associated control cabling, manufactured by KEC, India
• Six end cable terminations complete with mounting arrangements and steel support structures
• 132 kV line, control and protection panels — one set per bay — supplied by Nelumbo, India, including communication interfaces and integration with the station's existing SCADA system
• Six lightning arrestors with surge counters
• Associated civil works, including core cutting and foundations at structure and cable termination points
• Pre-commissioning and commissioning of the complete scope: insulation resistance, tan delta, high-voltage withstand, earth resistance and relay testing, protection and interlock verification, and busbar and dual-feeder protection panel testing
• Integration of the new bays into the station's common single line diagram and SCADA/automation system, including bay control unit (BCU) configuration and GPS time synchronisation
• Operator training and handover documentation for NEA personnel

Outcome

Both 145 kV GIS bays were installed, tested and energised, with station metering reading 134.0 kV line-to-line at 49.98 Hz. Testing and commissioning of the bay equipment, relay panels and SCADA interface was carried out by Mahavir Shree International's technical team alongside the manufacturer's commissioning engineer, with NEA staff participating throughout and Employer representatives witnessing all tests. The new single line diagram was integrated into the station's existing common SLD and automation system. Training was delivered to NEA operations personnel, and the facilities were handed over to the project office for commercial operation.