ISLAMABAD: The country suffered a major power breakdown on Friday morning, leaving countless cities, towns and villages in the four provinces and Azad Jammu and Kashmir without electricity for over five hours.

Karachi, however, remained unaffected while some other areas in Sindh and Balochistan were partially disturbed, an official working in a monitoring unit told Dawn.

“Initially, around 70 per cent of the country went out of the (power) system,” he added.

The fault reportedly occurred at a 500kv transmission line near Muzaffargarh at around 9.21am because of frequency mismatch at the National Power Control Centre (NPCC) as shortfall between demand and supply increased. This led to shutting down of about 15 power plants one after the other because of automatic safety systems and most parts of the country were “de-energised”, the official said.

He added that a number of safety and precautionary equipment introduced and practices done after last year’s numerous countrywide breakdowns had saved the system from usual cascading faults in the transmission line and was relatively easier to be restored.

A spokesman for the power ministry said the supply to 220kv and 500kv networks had been restored at around 12.45am and the entire distribution system was back to normal at 4.45pm.

An NPCC official said the production system was currently being run very tightly on the instructions of the Ministry of Water and Power to minimise fuel consumption and many oil-based plants were kept unutilised unless there was urgency.

On top of that, power generation from hydropower stations drastically declined because of annual canal closure. At present Mangla, Tarbela and Ghazi Barotha power stations are generating 800MW to 1,300MW against their peak generation of over 6500MW.

Mainly because of these two reasons, the overall production could not meet higher demand and the NTDC’s transmission system tripped because of its inability to meet NPCC’s frequency.

The power ministry’s spokesman Zafaryab Khan said tripping in the 500kv transmission line between Muzaffargarh and Multan had put the entire NTDC system into stress. He claimed that the power stations were generating more than the demand which the network could not transmit, resulting in backward flow as well as tripping.

But an NTDC official rejected this explanation, saying there should be no loadshedding if there is oversupply of power. He said that an average loadshedding of 6-8 hours was currently taking place on the national network. Also, he added, the transmission system had withstood a peak power dispersal of about 16,800MW in summer when the lines were already stretched because of hot temperatures and hence there was no reason for the network not to handle almost half of that generation in winter.

Zafaryab Khan said the NTDC system protection had been upgraded in the aftermath of last year’s blackouts. Consequently, the activation of zoning mechanism resulted in operations of north and south zones on separate island modes.

He said four distribution companies (Discos) in the south remained by and large unaffected. However, generation units in the north tripped due to higher than available generation loads.

He said the generation units were restarted gradually and supplies to big cities were restored in two to three hours. The circuit system of 220KVA and 500KVA was completely restored by 12.45am. The load gradually increased and supply to all Discos normalised by 4.45pm.

Mr Khan said the system protection measures taken last year had positively contributed to better handling of such emergencies this time as the system was restored in a short time, compared to the previous occasions when it took more than 24 hours to restore the entire network.

Published in Dawn, January 16th, 2016