Many parts of northern India, including Punjab and Haryana, plunged into darkness in the wee hours on Saturday as the northern grid collapsed due to thick fog.
The northern grid tripped at around 3.02 am following a technical snag in transmission lines that reduced power to zero at many sub stations, Power Grid CMD S K Chaturvedi said, adding that Delhi and NCR were not affected as precautionary measures like cleaning of transmission lines were taken in advance.
Besides, Punjab and Haryana, parts of Jammu and Kashmir and the Union Territory of Chandigarh were also affected due to the grid failure.
Although restoration work was on, authorities said, it would take another three to four hours for power supply to resume.
Power failure also threw train schedule out of gear in Punjab and Haryana and many trains were stranded midway, stopping abruptly due to disruption in electricity supply.
These trains, included Kalka-New Delhi Shatabdi and Amritsar-New Delhi Shatabadi. In addition, a large number of superfast, mail express and local EMUs were also running behind schedule.
"Due to thick fog, the northern grid failed, which also led to tripping of 400 KV and 220 KV power lines, causing disruption in power supply," Punjab State Electricity Board Member Transmission S C Sabharwal told PTI.
The grid failure also led to disruption of power supply to the hydel and thermal power plants in the states. PTI