Fog induces 21 power line outages in 3 days, midnight repairs avert crisis


In the wee hours of the night during the last three days, the country's grid managers have been waging a desperate battle against fog-induced transmission line outages.

On high alert after the grid collapse on two successive days in July, transmission grid operators in the northern region have successfully negotiated a total of 21 fog-induced forced outages during the last three days. Most of these were on lines operated by Power Grid Corporation Ltd (PGCIL) and the Uttar Pradesh Power Transmission Corporation (UPPTCL). The big challenge for the grid operators has been to restore the outages during the night itself, before the morning domestic heating load kicks in.

If key lines are are not repaired through the night, there is a chance that the surge in the load during the morning hours could mount additional load on to the remaining lines that could subsequently snap on account of overloading, triggering worries of a re-run of the massive northern grid collapse eleven years ago. On January 2, 2011, virtually all of northern India was blacked out for about 12 hours after line outages due to fog triggered the failure of a key substation in Uttar Pradesh, setting off a near-complete collapse of the country's northern grid.

On Sunday (December 23, 2012), there were five cases of transmission outages, according to the Transmission Elements Outage report for that day prepared by the Northern Region Load Despatch Centre. Tripping of power transmission lines happens when heavy fog mixes with unburnt carbon and other pollutants in the air and settles on the conventional porcelain disc insulators along the lines, shorting the conducting path and triggering a flashover. On Monday (December 24), the number of outages increased to 13, with lines operated by PGCIL and UPPTCL making up for most of the affected lines. On Christmas night, the number of outages were down to three, largely as the fog was considerably lower than on the previous two days.

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