By Chantelle Muzanenhamo
ZESA Holdings has attributed Monday’s nationwide blackout to a major fault on the Warren-Alaska 330kV transmission line that triggered the collapse of Zimbabwe’s electricity grid and disrupted power supplies across the country.
The blackout struck at 6:24pm on July 6.
In a technical update released on Tuesday, ZESA Holdings said the fault resulted in the loss of interconnections with neighbouring regional utilities before causing voltage instability and under-frequency conditions that forced local power stations offline.
“At 1824 hours, a major electrical fault occurred on the Warren-Alaska 330kV line leading to loss of interconnections with neighbouring regional utilities. Subsequently local generation was lost due to voltage instability and under frequency,” ZESA said.
The outage affected homes, businesses, hospitals and industries across the country, with electricity supplies disappearing almost simultaneously nationwide.
Shortly after the blackout, ZESA had only described the incident as a technical fault on its network while engineers investigated the cause. The utility later provided a detailed account of the sequence of events that led to the unprecedented collapse.
Restoration efforts began at 7:01pm, less than an hour after the outage occurred. Engineers managed to secure emergency supplies from South Africa’s Eskom, Kariba Power Station and Hydro Cahora Bassa, while Units 1, 2 and 3 at Hwange Power Station were gradually brought back into service.
“We are pleased to advise that by 2200 hours, power had been successfully restored to most of our bulk supply points across the country,” ZESA said.
The utility said that technical teams were continuing work to synchronise the remaining units at Hwange Power Station and carry out repairs and restoration work at Warren Substation, which supplies parts of Harare.
“Our technical teams are working tirelessly to restore and synchronise the remaining units at Hwange Power Station and to conduct works at the Warren Substation, which supplies parts of Harare,” the power utility said.
The nationwide outage comes at a time when Zimbabwe had been enjoying an unusually stable electricity supply.
Prior to Monday’s collapse, ZESA had reported more than 138 consecutive days without widespread load shedding, a milestone regarded as the country’s longest period of reliable electricity supply in nearly two decades.
The blackout therefore brought an abrupt end to a streak that had raised hopes of sustained improvements in power generation and distribution.
Energy experts note that while nationwide grid collapses are rare, Southern African power networks remain vulnerable to disturbances because of the interconnected nature of regional electricity systems. Zimbabwe relies on a combination of local generation and imports from neighbouring countries to meet demand.
Similar incidents have occurred in the past involving the regional grid. Zimbabwe and Zambia, which share infrastructure linked to the Kariba hydroelectric scheme, have previously experienced simultaneous outages triggered by faults on major transmission lines and interconnectors.
ZESA apologised to consumers for the inconvenience caused and said investigations into the fault and restoration process were continuing.