LAHORE: The country escaped a national power breakdown by a minute margin on Friday as some technical fault either in one of the dams or the 500kV transmission lines triggered a domino effect and took the entire system down, suspending supplies to the entire country, except Karachi and some parts of lower Sindh and, reportedly, to some parts of Balochistan.

The true extent and the cause of breakdown were contested by different organisations of the power sector which passed the buck to each other. And by evening they hid behind the argument that restoration of the system was the first priority and the cause would be investigated later.

Officials of the Water and Power Develop­ment Authority (Wapda) privately claimed that one of the main transmission lines of the National Transmission and Dispatch Com­pany (NTDC) connecting Tarbela and Man­gla dams tripped, causing the breakdown.

Parts of Sindh, Balochistan were also affected

On their part, NTDC officials insisted that Tarbela and Ghazi Barotha power houses developed some fault and fell out of the system. This pushed the frequency of system down to a critical level, triggering internal safeguards of the system and suspending nationwide supplies at 12.49pm.

“It was generation-related crisis, not connected to transmission,” an NTDC official claimed.

According to the general manager (hydel operation) of Wapda, hydel plants started coming back online soon, but the transmission system was not ready to take the load. Warsak Dam was restored by 2.30pm. The Tarbela power house was also started by 4pm, but it tripped again. Subsequently, all hydel stations were restored between 5.30pm and 7pm.

All generators were in working condition by 7pm, but could not send power out because of transmission system’s fragility, he said.

“By 7pm, only hydel stations came back, but none of the furnace oil plants (IPPs and Gencos) could be restored because that is a time-consuming process,” said another Wapda official.

Even the hydel restoration was partial by 8pm as Tarbela Dam had only five units running and Mangla Dam eight. Staff at these stations claimed that machines were ready but did not work because the transmission system was not ready to take the load.

“Bringing them back into the system is a major challenge as it is very hard to match frequencies and stabilise the system. That is why the entire work of the sector is still struggling to restore the system,” he added.

“Only Hubco survived the scare and continued contributing around 1,000MW to save Karachi and partially lower Sindh as the plant went into, what in technical parlance is called, island mode — disconnecting itself from the rest of the system,” explained a former head of Pepco.

Had Hubco fallen, it could have been total breakdown. Records show that it would have been the fourth in the country’s history and the third over the past decade.

“The critical question is why the NPCC (National Power Control Centre) failed to notice signs when the system went into distress because of a problem at any of the lines or power house. It is a state-of-the-art machine which indicates and registers fluctuations in micro seconds. Gross ignorance by the operator seems to be the only cause,” the former Pepco chief added.

He said reports that supplies to Balochistan were not disrupted could not be verified.

Published in Dawn, December 13th, 2014