LAHORE - The Punjab’s capital and rural areas around yesterday faced 10-hour blackout because of a disruption in the transmission system supplying electricity to the city of more than 10 million people.

The dense fog was being cited the reason for power breakdown which resulted in the tripping of 220kv Kala Shah Kaku grid station on 3.25am on Friday.

Reportedly, the tripping in the main transmission system of National Transmission and Dispatch Company Limited (NTDCL) also disrupted power supply to Gepco (Gujranwala Electric Supply Company) and Fesco (Faisalabad Electric Supply Company) for hours but Lahore was hit the most.

The spokespersons for NTDCL – the company managing the national transmission system –and Lahore Electric Supply Company – responsible for power distribution to Lahore Sheikhupra, Kasur and Okara –started blaming the breakdown on each other. No clue to the ‘fault’ was found till filing of this report.

Experts say though fog can disrupt electricity supply, the negligence on the part of Disco and NTDCL in maintaining transmission system result in such issues.

“Had the companies (both Disco and central NTDCL) maintained their transmission line properly, the possibilities of disruption in the electricity supply by fog would have been minimised,” they added.

Fog creates a carbon layer at power supply discs that disrupts transmission. But it can be fixed by proper maintenance, it has been learnt. Lesco spokesperson Imran Afzal said: “The NTDCL’s 220kv Kalashah Kaku grid station tripped at 3.25am because of fog and till 4.20am all its the nine grids and small grids of Lesco supplying power to Lahore and adjacent areas went off,” said Lesco spokesperson.

The NTDCL said the dense fog caused tripping of 132 kV transmission lines of Lesco and its impact was reflected to the connected 220 kV network of NTDCL.

“The cut-off load caused system over-voltage and tripping of NTDCL system.”

The spokesperson said, “The NTDCL’s protection system operated timely and saved the equipment from the damage as well as avoided countrywide breakdown.”

The NTDCL controls the main grid stations of 550kv and 220kv it established across the country at different locations from where the power distribution companies (Discos) manage electricity supply in their limits by installing small grid stations of 132kv and 66kv.

There are 94 grid stations of Lesco of 132kv and six grid stations of 66 kv whereas 34 grids have been installed by independent consumers. Lahore is being supply electricity from 42 grids of 132kv and two grids of 66kv.

“All 42 grids of Lahore remained closed from 4am to 9am. The restoration in power supply started after that and it completed till 2pm,” said a Lesco official.

The company also closed grid stations in Okara and Kasur as precautionary measure to protect the system, resulting in up to five-hours power cut there.

The power cut grinded life to a standstill in the affected areas where water fell short and school could not attend their school. Officials fear the issue may resurface if the present weather condition persist as the companies don’t look after transmission system properly. The country has witnessed more than three major blackouts in this year due to collapse in transmission system plunging into darkness the big and small cities and rural areas for hours.