A blame game has begun between Tata Power and state-run transmission utility Mahatransco over the massive power outage in the financial capital earlier this week.
Mahatransco (Maharashtra State Electricity Transmission Company Limited - MSETCL) Chairman and Managing Director Dinesh Waghmare said Tata Power's plants took time to start generating electricity following the grid collapse on Monday morning, resulting in the specially created 'islanding' system not working.
Hydel power stations can start generating power in 10 minutes, but Tata Power's took over five hours, while its thermal power stations came on board only past midnight, resulting in longer time required for restoration of power to residents, Waghmare told a TV news channel on Thursday.
Countering this, Tata Power on Friday said "the inconvenience caused to the Mumbai consumers was due the MSTECL transmission system failure which led to cascading impact on all the downstream suppliers of electricity including Tata Power and BEST."
Typically, half of the financial capital's power requirements are served by MSETCL, while private sector Tata Power and Adani Electricity Mumbai take care of the other half through their generating stations,
A bulk of MSETCL's power is distributed through the sub-station at Kalwa, he added.
Waghmare termed it as an "unprecedented" event, where two of the four lines getting power to Kalwa sub-station got physically snapped -- one was under maintenance and the last one from Kharghar was manually shut on the day as there were sparks observed due to the extra load on Monday.
The islanding system would have saved the day for Mumbai, Waghmare said, adding that the system was specifically created to avoid a total breakdown in services and relies on Tata and Adani's power
However, two "major units" of Tata were not functional on the given day, Waghmare said, adding that Tata's power stations are not in grid many a time or may have been under maintenance which delayed their coming on-board.
A 250-MW thermal unit of Adani also stopped generating power the same day at 1300 hrs, aggravating matters, he said.
"Mumbai's islanding system that saves the city from major power outages was successfully separated at 9.58 am, however it could not hold sudden 1000 MW load drop at 10:05 hrs. Tata Power rapidly initiated restoration by bringing in power from its three Hydro Units and activating its Trombay gas and coal units as soon as the MSETCL transmission lines were connected," the Tata Power statement said.
Tata Power started restoring supply to its consumers progressively from 12 noon onwards and throughout the course of the day, it added.
Waghmare further said a detailed enquiry will help find out if there was any sabotage in the matter.
Maharashtra Power Minister Nitin Raut had on Wednesday hinted at the possibility of sabotage.
In a rare power outage on Monday morning, trains came to a halt mid-track, employees working from home got impacted and people suffered inconveniences like getting stuck in elevators.
Power was completely restored only after midnight in some areas and supply continued to be erratic on Tuesday as well in some pockets.
Under the 'islanding system', an area is supplied electricity in such a way that it is insulated from any grid failure or other technical issues happening outside the zone.