A power surge that caused a widespread blackout in Spain and Portugal was the most severe in Europe in the last 20 years, and the first of its kind, a report has found.
Damian Cortinas, president of the association of electricity grid operators Entso-e, said the incident was the first known blackout to be caused by overvoltage, which occurs when there is too much electrical voltage in a network.
This is new territory, Cortinas said, adding the role of Entso-e was not to apportion blame to any party over the cause.
April's outage caused significant disruption for nearly a day when it plunged areas into darkness, cutting internet and telephone connections and halting transport links.
The blackout affected large parts of Spain and Portugal, and briefly impacted southwestern France. The report, released on Friday, focused on the condition of the power systems on the day of the outage and the sequence of events leading up to it.
A series of cascading overvoltages - an increase in the electrical supply voltage above the established norm - was identified as the cause of the outage.
According to the report, automatic defence plans were activated but could not prevent the power system shutting down. Spain's government believes the Entso-e report supports its findings from separate investigations, which suggest that national grid provider Red Eléctrica and private electricity companies were at fault.
Meanwhile, the outage has triggered debates concerning Spain's energy model, particularly the reliance on renewable sources and the diminishing role of nuclear energy. Emergency responders faced significant challenges, with reports of trapped individuals in elevators and disruption in routine hospital procedures.
The events surrounding the blackout have spurred ongoing investigations, with a detailed report set to be published early next year to further analyze the causes and implications of this unprecedented incident.
