The Centre has sanctioned ₹671.72 crore for the upgrade of electrical infrastructure on the north-south corridor (Blue Line) of Metro Railway.
The upgrade is aimed at increasing train frequency. At present, the Blue Line has a peak-hour frequency of five minutes. The carrier plans to reduce the gap to two-and-a-half minutes by 2030.
“In a major step towards enhancing Metro Rail capacity, works worth ₹671.72 crore have been sanctioned for strengthening the north-south corridor of Kolkata Metro Railway,” said a Press Information Bureau release dated May 2.
Of the total amount, ₹291.06 crore will be used to set up seven additional traction substations.
The remaining ₹380.66 crore will be used to replace electrical infrastructure such as transformers, rectifiers, high-speed circuit breakers and a network of cables.
Engineers said that for trains to run at shorter intervals, each station should have a traction substation.
The Blue Line, the country’s oldest Metro network, was built in the 1980s. The corridor still relies on five receiving substations, which receive high-voltage electricity (33KV alternating current) from CESC and step it down to 11KV before feeding it to traction substations, which then convert it into low-voltage direct current (750 volts) for railway propulsion.
The traction substations feed the third rail that powers Metro trains.
“When this system was built in the 1980s, traction substations were not equipped to handle high-voltage electricity like 33KV. That is why receiving substations were needed. Now, technology has advanced, and traction substations can handle 33KV power. The older receiving substations have also neared the end of their shelf life, and we will not need them once the new traction substations are ready,” explained a Metro engineer.
The Blue Line has 26 stations, 13 traction substations and five receiving substations. Eight more traction substations would mean one for every station. Additionally, another would be placed between Dum Dum and Belgachia, as the distance between the two stations is longer than average.
Two new traction substations at Chandni Chowk and Gitanjali (Naktala) are nearing completion and should be functional by July-end. The seven additional ones — for which funds were sanctioned on May 2 — will be built at Kalighat, Netaji Bhawan, Maidan, Esplanade, MG Road, Sovabazar, and between Belgachia and Dum Dum.
The traction substations will help save both money and energy.
Replacing the steel third rail with an aluminium one is vital to reducing train gaps. Aluminium is a much better conductor of electricity.
It will reduce voltage drops and energy losses and help achieve faster train acceleration.
The upgrade is being done in phases. Most of the underground section has already been upgraded. The elevated section between Tollygunge and Kavi Subhas (New Garia) remains.