LAHORE/ISLAMABAD - One of the worst blackouts in the country’s history hit Punjab, KP and parts of Fata on Friday due to some unidentified technical fault in transmission system of northern part of the national electricity grid.

The fault in a major line of the National Transmission and Dispatch Company Limited (NTDCL) occurred in the afternoon at around 1:30pm, leaving almost whole of Punjab and Khyber Pakhtunkhwa provinces as well as some parts of Federally Administrated Tribal Areas without electricity for hours.

The supply restored partially in Lahore and other areas later in the day, but around 40 per cent population of Punjab and KP was still without power until midnight. The officials said that electricity would be fully restored by Saturday morning.

The national grid which is currently receiving around 13,000MW electricity from hydel, thermal and independent power plants (IPPs) to partially meet the country’s demand was left with only 5,000MW for Sindh and Balochistan due to the crisis.

The trouble emerging in transmission line from Tarbela Power Plant spread in seconds to the connecting system of Ghazi Broth Hydropower Project, Mangla Dam, Chashma and Kepco.

A spokesman for the Ministry of Water and Power said the blackout was due to a fault in 500KV transmission line. “We have two lines – 500KV and 220KV; at around 1:30, some technical fault developed in 500KV transmission line, which gradually shut off the power supply from Tarbela to Guddu,” he said.

Another high official of the power sector requesting anonymity said, “The fault occurred in 500kv transmission line from Tarbela to Lahore due to dropping of frequency. Unfortunately, the frequency could not be controlled by the NPCC (National Power Control Centre).” He explained that the frequency dropped from 50Mh to 47Mh, which had an immediate cascading effect on the northern part of transmission system.

Another official, also requesting not to be named, said engineers were yet to determine the real cause of the problem since the frequency issue must not have happened in the winter season when there is not much load on the overall system. In the meantime, they were making electricity supplied to parts of Punjab and KP.

“Faults emerged only in transmission lines. There is no issue with the hydel and thermal power stations, and they are all safe,” said power ministry officials. They added the transmission system in northern part supplying electricity to Sindh and Balochistan was also functioning normally.

They also claimed that around 5,500MW electricity was restored in the transmission lines of Mangla, Terbela and Ghazi Brotha power plants. The lines from thermal power plants and Chashma Hydel Power Plant would also be restored till morning, they said.

The long hours of shutdown badly affected the routine life. It created severe water shortage and other problems for millions of households. Electricity went off in the northern parts of the country when people were busy in preparations for the Friday prayers.

The main hospitals in Lahore and other cities and Lahore airport, railways station also badly suffered as flights and trains were delayed while ICUs and emergencies in hospitals ran on generators. The Ministry of Water and Power said priority grids are those providing electricity to hospitals and airports and will be the first to be restored.

Overall, there was 10-hour long shutdown in all major cities of Punjab and KP and rural limits of seven distribution companies of the country. All areas under the jurisdiction of Islamabad Electric Supply Company including the Prime Minister House and the Presidency also remained without power for hours on Friday.

“We had zero power supply from around 1:30pm to almost 6pm,” said an Iesco official. He said all the areas under their jurisdiction, including Chakwal, Jhelum and Attock remained powerless till 6pm.

More than half of the country remained without electricity for so long but the power ministry was clueless about the real reason for the fault even after eight hours. “We are not certain right now but we would find out,” officials said.

All the affected distribution companies, except Iesco, remained without supply till late Friday night.