Power officials recuperating from two successive and massive grid collapses had a close shave on Monday morning, offering just another reminder of how close to the brink India’s fragile grid infrastructure is. In a span of just three hours, 16 units of three of the country’s largest hydro stations shut operations one after the other, blaming high silt levels in river water. The grid frequency plummeted to a record low of 48.8 Hertz (Hz), way below the permissible lower grid frequency limit of 49.5 Hz. The panic created was such that Power Secretary P Uma Shankar is learnt to have made a dash to Power Grid Corporation’s control centre in South Delhi, where he stayed put for a good three hours till the situation stabilised, officials involved in the exercise said. Frayed tempers led to calls to sack those involved in the latest incident of grid disturbance, which was triggered by the 1,500 MW Nathpa Jhakri hydro power station — the country’s largest hydro station — and J P Power Ventures’ 1,000 MW Karcham-Wangtoo, the country’s largest private hydro station, abruptly shutting down operations. NHPC Ltd’s Chamera station, also in Himachal Pradesh, too shut down, adding to the worsening grid situation. “The Nathpa Jhakri and Karcham Wangtoo units, which were running way above capacity till early Monday evening, shut down in quick succession without adequate notice to the grid managers. While silt levels had touched very high levels of over 5,000 ppm (parts per million), the station managers should have given enough warning, and not just a 15-minute notice. There was no possible contingency and the frequency plummeted, pushing the grid to the brink again,” an official with the northern region load despatch centre said. Most northern states sharply cut their load, thereby averting a crisis for now.