"Western region was under drawing with no reduction in the generation capacities and the northern region was overdrawing resulting in inter-regional grid imbalances," a source privy to the preliminary findings of the committee said.
Another reason for the grid collapse could be constraints in the inter-regional grid linkage between the Northern and Western grid due to upgradation work at the Bina-Gwalior transmission lines in Madhya Pradesh.
"It (grid collapse) occurred despite a series of warnings to all the State Load Despatch Centres (SLDCs) which were not maintaining grid discipline," the source said.
In the National Grid system, the control to isolate certain areas lies with the state utilities and there is no auto switch off system of any particular region.
"This could have resulted in the collapse," he added.
The government had constituted a committee headed by CEA Chairman. The other members of the committee include former MERC Chief, CMD Power Grid and CEO, POSOCO (Power Operation System Company Ltd).
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In the worst ever power crisis, over half of the country's population in 21 states went without electricity for several hours on July 31 as three major transmission grids failed, bringing northern, eastern and north-eastern regions to a grinding halt.
The massive failure happened less than 24 hours after the Northern Grid collapsed and was revived on July 30.
On July 30, a disturbance occurred in the Northern Region Grid which led to failure of power in eight -- Uttar Pradesh, Uttarakhand, Rajasthan, Punjab, Haryana, Himachal Pradesh, Jammu & Kashmir, Delhi and Union Territory of Chandigarh.