KARACHI: A major power breakdown hit 90 per cent of the metropolis early Friday morning as power transmission lines near Jamshoro tripped, triggering a failure in the K-Electric (KE) grid.

A 500kv Hub-Jamshoro transmission line which earlier tripped due to dense fog has now been restored, a Ministry of Water and Power official said.

A separate 220kv transmission line from Jamshoro was repaired earlier, and is supplying power to the KE system, the official told DawnNews.

KE in a statement attributed the tripping of transmission lines to high levels of humidity and said most grid stations had been energised via restoration of the alternate 220kv transmission line.

The transmission lines are part of the National Transmission and Despatch Company's (NTDC) distribution system.

A senior official in the NTDC told DawnNews that 80pc of KE's electricity demand was being fulfilled by the NTDC's transmission lines, which had tripped.

The official said that if KE had an adequate load management mechanism or backup system in place, there would not have been any breakdown.

Following repair of the 220kv line, KE began to receive 250 megawatts from the NTDC system. When KE restores their own system ─ which failed following the breakdown earlier ─ they will be able to draw an additional 500MW from the NTDC system, according to the ministry official.

The 500kv power line tripped due to dense fog and was repaired by NTDC engineers, an initial report submitted to the Ministry of Water and Power by the National Power Control Centre stated, he said.

Defence, Clifton, Saddar, Gulshan-i-Iqbal, Tariq Road, Drigh Road, Gulshan-i-Maymar, Buffer Zone, Gulistan-i-Jauhar, Safoora Goth, Steel Shadman Town, Gurumandir, Lasbela, Liaquatabad, Lyari, Ranchore Lines, Shah Latif Town and Federal B Area were among the areas affected by the power breakdown earlier.

Total electricity demand in the metropolis varies according to the weather. Over the past month this winter, the city has consumed an average of 900-1,200MW according to official estimates.

Total supply to the KE system from NTDC is around 650MW, a 24-hour average figure provided by KE officials.

This is around 72pc of 900MW. The difference must be met by KE.

KE relies on NTDC for cheap power. When power is made in-house, costs are higher due to the price of furnace oil, as well as other production costs.

There have been at least three power breakdowns in various parts of the country over the past month.