LAHORE: Several cities and towns in Punjab suffered an electricity breakdown of up to 12 hours after transmission lines of 200kV and 500kV tripped on Friday.

The breakdown occurred at about 3.30am, apparently due to dense fog and pollution, with 100 of the 130 grid stations of 132kV tripping within the territorial limits of the Lahore Electric Supply Company (Lesco) and many areas under the Gujranwala Electric Power Company (Gepco), the Faisalabad Electric Supply Company (Fesco) and the Multan Electric Power Company (Mepco), according to sources.

The power ministry constituted a high-level committee to investigate the matter after the National Transmission and Despatch Com­pany (NTDC) and the distribution companies (Discos) blamed each other for causing the 12-hour outage.

Dense fog, pollution said to have caused power breakdown

“The committee will ascertain the actual reasons behind the tripping — whether the breakdown occurred due to the tripping of Discos’ 132kV transmission lines or the NTDC’s 200kV transmission lines,” Lesco’s chief executive officer Syed Wajid Ali Kazmi told Dawn.

He claimed that it was the tripping of the NTDC’s 220kV lines that led to a fault in most of the 132kV grid stations and transmission lines operated by the Discos.

According to the NTDC, Lesco’s power distribution system collapsed first. This caused the 220kV and 500kV transmission lines and grid stations to trip, leaving several areas without power for several hours.

“The fault first developed in 132kV lines that later on shifted to the 200kV and then the 500kV lines maintained and operated by the NTDC,” a spokesman for the company said.

Later in a press release, the NTDC said that dense fog had caused Lesco’s 132kV transmission lines to trip and the impact was transferred to the connected 220kV network run by the NTDC. The cut-off load had caused a system over-voltage and the NTDC system tripped as a result.

“The NTDC’s safety system triggered timely, saving the equipment from damage and preventing a countrywide system collapse. The affected portion of NTDC’s transmission system was restored by 11am.”

On the other hand, the Discos’ chief executive officers termed the NTDC’s system responsible for affecting their 132kV transmission lines. “Two of the NTDC’s 220kV grid stations at Pindi Bhattian and Sukheki had tripped first, causing our 132kV stations at Aimanabad and Shaheenabad and several feeders to trip,” Gepco CEO Muhammad Akram Chaudhry said.

The lines might trip again if no rain occurred and foggy weather persisted amid pollution, covering the transmission lines with dust particles, Mr Chaudhry said.

Reacting to the NTDC’s claim, the Lesco CEO said the fault had developed in a majority of NTDC’s nine 220kV grid stations and had gradually started tripping their 132kV grid stations. “Till 4.30am, 100 of our stations had tripped, leaving almost all of Lesco’s urban and rural areas without power. However, we succeeded in restoring the tripped stations by 3.30pm after some of the 220kV NTDC lines resumed operations,” Mr Kazmi said.

He argued that if the fault had developed in the 132kV lines alone, only five or six stations would have broken down. “How could 90 per cent of Lesco’s 132kV stations trip within an hour while all the 220kV lines were in order,” he said. “We have the relevant record to prove that the 220kV transmission lines had tripped first and caused our 132kV system to trip. We will present the proof before the inquiry team constituted by the federal secretary for water and power,” he said.

Published in Dawn, December 10th, 2016