Kolkata's Metro Railway boasts of installing India's longest circuit breaker panel

This replacement took place along the Blue Line that connects Kavi Subhash (New Garia) in South Kolkata to Dakshineswar in the city's northern fringes. Incidentally, this stretch is an extension of India's first Metro service that started in Kolkata in 1984. On Monday, Metro Railway general manager P Uday Kumar Reddy energised the 33 kV TSS of the Blue Line's first Gas Insulated Switchgear (GIS) Panel. This state-of-the-art TSS not only comprises the GIS 33 kV high tension panel, it also has India's longest HSCB panel, Insulated-Gate Bipolar Transistor (IGBT)-based regenerative battery charger, 33 kV dry type traction transformer and this Line's first 3 MW twelve pulse rectifier," said Kausik Mitra, CPRO, Metro Railway. The 11 kV TSS that this system replaced had a six-pulse rectifier and an 11 kV dry-type traction transformer. The new transformer-rectifier set has a 50 per cent higher capacity. This same model shall be utilized for the upgradation and augmentation of all old substations of the Blue Line for improved services. According to Mitra, the HSCB panel - being touted as India's longest - is actually a combination of 17 HSCBs. This will allow power blocks for regular maintenance by the civil engineering department. Now that the number of rakes in service in the Blue Line has risen to 34, regular maintenance was becoming a problem with the old system in place. "We planned this work in July and a day-wise monitoring plan was in place before the substation shutdown programme was finalised. The work started in August and was completed within two months. There was no service disruption during this period. The final tests were carried out in the first week of October and approval for charging the substation was granted by the electrical inspector to the Government of India a week ago," Mitra said. Upgradation to the 33 kV network has multiple benefits, he said. It will lead to reliability and cost reduction through the removal of all other switch gears in the network. Distribution loss from cables will be reduced due to the higher voltage. The new system is also more environment friendly, according to the CPRO. Metro Railway expects that this replacement will help it save nearly Rs 350 crore in capital expenditure for the entire Blue Line in equipment replacement and energy-saving costs. The traction substations at Belgachia and Dumdum will be upgraded by December 2024 and February 2025.