Around this time next year, the city will bid a final goodbye to the last vestiges of the Direct Current power supply that is still in use on the suburban railway network.

The Central Railway (CR), the last zone in Indian Railways to use 1,500-volt Direct Current (DC), will switch over to 25,000-volt Alternating Current (AC) entirely, by June-July next year, making the 90-year-old 1,500-volt DC power system redundant.

Representational pic

The CR authorities will complete the first stage of the power conversion on the Thane-CST stretch by December this year. At present, there are two different types of power lines on the CR route.

The Thane-Kalyan-Karjat/ Kasara stretch and Thane-Kurla LTT (Lines 5 and 6) are supplied by 25,000-volt AC power, while the Thane-CST slow and fast lines and the CST-Panvel Harbour line corridor runs on a supply of 1,500-volt DC.

“We will complete the power conversion up to CST by December, and in another six months, conversion will be completed on the Harbour line as well,” said S Sood, general manager, Central Railway.

The work of setting up substations and cables is already in progress on the Thane-CST stretch, to facilitate the supply of 25,000-volt AC power. Even the extra buffering of overhead cables for road- and foot over-bridges has been completed.

The switchover to 25,000-volt AC is expected to improve efficiency of services, reducing breakdowns and also helping the railways save up to Rs 120 crore per annum from reduced transmission, conserving 33 per cent electricity. The main line has 75 rakes, 65 of which can run on both AC and DC traction.

The remaining 10 rakes are DC-compatible and are used solely on the CST-Thane section. “There are operational problems, as DC rakes cannot enter AC territory. We are running retrofitted trains, in which changes have been made in old trains by adding new circuits,” said a CR official.