Darkness descended over several parts of the city for the second winter evening in succession as the principal power-generating station of the CESC, at Budge Budge, remained out of the supply chain.

The shortfall in the areas fed by the private power utility shot up to 165 mw around 6.30 pm, disrupting supply to Calcutta and its adjoining areas.

“We expect the situation to improve on Friday, as one unit at Budge Budge should start generating from early morning,” said a CESC official.

The city suffered power cuts for the first time this year on Wednesday evening, when a giant 250-mw unit at Budge Budge collapsed after it sprang a tube-leak in its boiler. The other unit of the power plant had been shut down on February 1 for maintenance and repairs.

CESC sources said engineers had been working on a war footing since Wednesday to bring the Budge Budge unit back on stream. But as soon as dusk set in on Thursday, large pockets of Calcutta plunged into darkness. In some parts, even the streetlights went out.

Parts of central Calcutta and almost all of south Calcutta, including Jadavpur, Ballygunge, Kasba, Jodhpur Park, Behala, Garden Reach, Entally and Park Circus, were badly hit, as they are largely dependent on power feed from the Budge Budge plant.

Blackouts ranged from two to three hours as the CESC resorted to rotational power cuts. Sources in the private power utility said that special measures were taken to supply uninterrupted electricity to the Calcutta Book Fair.

North Calcutta was better off, as it is largely supplied by the CESC’s power-generating units at Titagarh.

The state electricity board (SEB) supplied 359 mw to the CESC grid on Thursday. The CESC’s own units generated around 461 mw. Officials said the SEB has been keeping a close watch on the supply situation and is ready to pump more power into the CESC grid, if required. “We could have supplied more power to the CESC even on Thursday, but it stopped after taking 359 mw, which is about 130 mw more than what it usually draws from the SEB grid,” said an official.

“There is no problem with the generation from the Kolaghat and Bakreswar plants and we drew about 470 mw from the NTPC plant at Farakka,” he added.