Metro Railway, Kolkata, has upgraded a 40-year-old 11 kV Traction Sub Station (TSS) at Noapara with India's longest High-Speed Circuit Breaker (HSCB) panel.

This installation is part of the Blue Line, which links Kavi Subhash (New Garia) in South Kolkata to Dakshineswar in the north, an extension of India's first Metro service that began in 1984.

"Metro Railway General Manager P Uday Kumar Reddy activated the 33 kV TSS featuring the Blue Line's first Gas Insulated Switchgear (GIS) panel. This advanced TSS includes the GIS 33 kV high tension panel, the longest HSCB panel in India, an IGBT-based regenerative battery charger, a 33 kV dry-type traction transformer, and a 3 MW twelve pulse rectifier," stated Kausik Mitra, CPRO of Metro Railway.

The previous 11 kV TSS had a six-pulse rectifier and a dry-type traction transformer, while the new system offers a 50% higher capacity. This upgraded model will be used for enhancing all old substations on the Blue Line to improve service.

Mitra noted that the HSCB panel, comprising 17 units, facilitates power blocks for regular maintenance, addressing issues arising from the increased service of 34 rakes on the Blue Line.

"We planned this project in July with a detailed monitoring strategy before finalizing the substation shutdown. Work commenced in August and was completed within two months, with no service disruptions. Final tests were conducted in early October, and the electrical inspector approved the charging of the substation last week," added Mitra.

The transition to a 33 kV network brings several advantages, including improved reliability, reduced costs from the elimination of older switchgear, decreased distribution losses due to higher voltage, and a more environmentally friendly system.

Metro Railway anticipates savings of nearly Rs 350 crore in capital expenditure for equipment upgrades and energy costs across the Blue Line. Upgrades for the traction sub-stations at Belgachia and Dumdum are scheduled for December 2024 and February 2025, respectively.