NEW DELHI: Brace for blackouts. The western grid managers have asked states to shed load as the doddering power supply situation received a jolt on Wednesday after major utilities switched off several units due to coal shortage, payment default and technical snags.Government sources said the Western Regional Load Despatch Centre reported a loss of 7,713 mw of generation capacity in the region as several plants went off the grid. The western grid itself is running short of 3143 mw supply.Central grid managers told TOI grid stability was being maintained by asking states to shed load and reducing the amount of power scheduled for supplying to states in other regions. But ripples of the outage may travel beyond the western region to hit northern states since some of the big plants operated by state-run NTPC, Adani Power and Tata Power supply electricity to Haryana, Punjab and Rajasthan.Shortfall in the committed supply from the western plants could build up pressure on the northern grid, which has states like UP and Haryana. These states are facing severe power crunch due to shutdown of their own power stations, lack of capacity to buy from outside to meet rising demand on the back of extended dry spell.Several plants are running way below their capacity due to coal shortage, especially those belonging to Mahagenco. The utility’s Parli unit-4 has been shut for some time now due to shortage of water on the back of the long dry spell in Maharahtra.The big loss in generation has been from NTPC, India Bulls, Lanco, Tata and Adani. The first three utilities have switched off 1580 mw due to coal shortage.But the big hit was delivered by the Adani group, which suddenly pulled the plug on 2970 mw capacity citing coal shortage and payment default by Haryana as reasons.Next door, one of the 800 mw units of Tata group’s Mundra UMPP blew the fuse due to problem in ‘re-heater isolator’.. Another unit has been under repair for boiler pipe leakage. The company said the Mundra plant was maintaining the declared generation capacity. The 4,000 mw pproject has five units of 800 mw each.It was the shutdown by the Adani group that took grid managers by surprise. The shutdown came two days after the Supreme Court on Monday stayed an interim order of the Appellate Tribunal for Electricity allowing it tariff hike to compensate for rise in imported coal price. The interim order would have benefitted Tata Power too.The consumer states of both these companies have opposed tariff hike outside the timeline provided in the power purchase agreement. An Adani spokesperson declined to comment on how much was due from Haryana.