Islamabad: National Electric Power Regulatory Authority (NEPRA) has issued the inquiry report of blackout in country and has held some Guddu Thermal Power Plant officials responsible for the power outage.

As per inquiry report, the causes of blackout are the persistent bolted fault at Guddu switchyard and -resultant Unstable Power Swing in the power system.

“On January 09, on closing of a 220kV circuit breaker at Guddu switchyard, bolted fault occurred as the earth switch of related Isolator was left closed,” read report.

The report added that the bolted fault which consequently resulted in the black out was created due to the negligence of the staff of Guddu Power Plant.

The restoration process was initiated quickly by the power plants and some of the power plants took more time than the specified.

The Water and Power Development Authority (WAPDA), Hydel power plants were synchronized with the National Grid within 20 hours.

In case of K-Electric, the power plants were synchronized with its system in 17 hours and overall, NTDC's power supply was restored in 20 hours, whereas ICE took about 22 hours for the restoration.

Most of the thermal power plants were synchronized with National Transmission and Despatch Company (NTDC) within 27 hours.

Moreover, the North and South zones created an unbalance of generation as in south, the generation was higher as compared to the connected load whereas, in North, the power plants experienced excessive connected load.

This unbalancing of generation and connected load contributed towards complete breakdown.

Earlier in January, country plunged into darkness after the NTDC power system encountered a major breakdown due to the tripping of the Guddu Thermal Power Plant.