KARACHI, Oct 28: The transmission and distribution system of the Karachi Electric Supply Corporation finally capitulated to the ongoing heatwave when a technical fault occurred around noon, depriving almost the entire city of its power supply.

While irate callers criticized the KESC for spending so little on the maintenance of the transmission and distribution system that it remains vulnerable to the vagaries of nature, a spokesman for the power utility explained that an extra high tension line between the Bin Qasim power station and the Pipri grid had tripped at around 12.30pm.

He added that KESC engineers had made speedy recovery and normalized the city’s power supply system within three hours.

The callers, however, told Dawn that in many areas power supply had not been restored at around 3.30pm.

Calling from Defence, Phase VI, Dr Fatima Hasan said it was beyond her comprehension why the KESC could not ensure uninterrupted power supply. “I was at my clinic in Clifton when the power breakdown occurred around noon. I called home and found out that my children had been without electricity since morning. I returned home in the evening when the power supply had been restored. Before long, we had another power cut. When I called my complaint centre I was told that loadshedding was on. My family spent the entire day without electricity.”

Talking about the unforeseen technical fault, the KESC spokesman said that suddenly around 12.30pm the third line developed a technical fault and tripped. “Therefore, the entire load of 875 megawatts from the Bin Qasim station moved to the fourth line, which has the maximum load carrying capacity of 400 megawatts, resulting in tripping of the fourth line and detaching of the power station from the distribution system. The entire process created an over-frequency situation at the station which activated the safety switches installed at the generating machines. Thus the power station was automatically shut down.”

Some high-ranking officials of the KESC told Dawn that the power breakdown had been so extensive that it had left only three out of 51 grid stations in the city working.

“The cascading effect destabilized the entire power supply system and the Water and Power Development Authority circuit. The circuit of the Independent Power Producers was also desynchronized. The three grid stations which remained on were being energized by the Korangi Thermal power station.”

They added that major maintenance work was being carried out on the third and fourth extra high tension lines.

There are only four extra high tension lines which carry power from the Bin Qasim station to the city. The Bin Qasim power station supplies around 900-1,000 megawatts to the city, the independent power producers 250 megawatts, the Karachi Nuclear Power Plant 70 megawatts, the Pakistan Steel 20 megawatts and the Water and Development Authority 500-600 megawatts.

Meanwhile, residents of different localities complained that their areas had been facing acute power crisis for many days which had nothing to do with Monday’s breakdown.

Imran Abbasi, a resident of North Karachi, Sector 11-A, told Dawn his locality had been without electricity for more than three hours the previous night. “When I called my regional complaint centre, they told me that it was an isolated fault. It was absurd because the entire area in our neighbourhood had been dark and they were telling me it was an isolated fault,” he said.