Line tripping at Egbin substation caused blackout, says TCN

The Transmission Company of Nigeria (TCN) has denied reports of a national grid collapse.

Ndidi Mbah, general manager of public affairs at TCN, provided clarification on the incident in a statement on Tuesday.

On Monday, the country suffered another nationwide blackout — the fifth in 2024.

According to various distribution companies (DisCos), their feeders became inactive, resulting in widespread blackout across the country.

Data from TCN’s generation trend showed that the grid collapsed at about 1:30pm on Monday and dropped from 3,151 megawatts (MW) to as low as 1,255MW in an hour —  and later to 823.5MW before the total drop to 0.00.

Mbah said contrary to reports, the incident was limited to a line tripping at the Benin-Egbin 330kV isolator.

“At about 6:10pm yesterday, 5th August 2024, power supply was restored to areas that had been affected by the arcing on the Benin-Egbin 330kV isolator which caused lines tripping and consequent loss of supply to some areas,” Mbah said.

“However, contrary to media reports, the incident did not cause a system collapse.

“The lines tripping started earlier at about 2:47p.m. yesterday, with a heavy system surge that led to the arcing of Benin-Egbin 330kV line isolator fingers at the Egbin Transmission Substation switchyard. 

“This resulted in a tripping at the Egbin Generating Station, which caused the loss of power supply to all the Egbin Transmission Substation’s outgoing lines.

“This led to an exponential increase in load on the Osogbo-lhovbor 330kV line 1 with serious arcing of isolator terminals on the Osogbo-lhovbor 330kV line 1. 

“To ensure that the sequence of events does not affect the nation’s grid, the Osogbo-lhovbor 330kV line was opened to temporarily cut off the flow of electricity on that line.

“At about 2:56pm, however, the Benin-Egbin 330kV line 1 Circuit Breaker also tripped at the Benin Transmission Substation end and this resulted in the loss of supply to Lagos axis, parts of the South West Region, parts of the North Central and Abuja.

“Meanwhile, other areas, including the South Eastern region, North East, and other parts of North Central and South West, had full power supply.”

Mbah said the line tripping was quickly rectified, enabling the grid controller to restore full bulk power supply through the transmission lines at about 6.10pm on Monday.