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A malfunction at the Apolo Substation in Havana, triggered a chain reaction on Tuesday that took key generating units of the National Electric System offline and left dozens of neighborhoods in multiple municipalities of the capital without electricity.
The Electric Union (UNE) confirmed in an official statement that the failure in Apolo "caused several substations in the capital to go offline" and that "oscillations occurred that took Units 6 and 8 of the Mariel Thermoelectric Power Plant and Unit 3 of the Renté Thermoelectric Power Plant out of service."
The entity specified that "the rest of the system is currently operating" and that "the causes are being investigated."
Radio Reloj confirmed that efforts were underway to restore the outage, caused by a fault in the 9020-9025 lines of the Naranjito-Melones substations.
The Electric Company of Havana (EELH) reported on its Telegram channel, starting around 1:00 PM, a sequence of disruptions that extended throughout the afternoon and into the night.
At 7:57 PM, the EELH reported that "the following substations are affected by a shot in the 110 kV lines: Naranjito, Apolo, Melones, Príncipe, Cerro, Talla Piedra, and Párraga."
The Automatic Frequency Discharges (DAF) —a mechanism that disconnects circuits when the frequency drops below safe levels— affected the municipalities of Boyeros, Plaza-Marianao, Playa-Plaza, Habana del Este, and Marianao, according to a report at 7:41 pm.
A second DAF outage left underground areas of Old Havana, Plaza, and Centro Habana without electricity, as well as several quadrants of El Cerro.
The affected municipalities also included Playa-Lisa, Cotorro, and 10 de Octubre, where circuit gunfire was reported due to possible malfunctions in the distributions of Luyanó and surrounding areas.
In Boyeros, a fault was also detected due to a damaged transformer at address 304 between 187 and 191, in El Chico.
The incident exacerbates an energy crisis that in May surpassed deficits of 2,100 MW, with only 1,230 MW available against a demand of 3,250 MW on May 13.
The Mariel and Renté power plants have frequently been the focus of outage reports throughout 2026, with units going in and out of the system, contributing only a few dozen megawatts to the nighttime peak.
On May 25, Havana experienced 23 hours and 11 minutes of power outage in a single day, and on May 16, it was estimated that 51% of the country was without electricity simultaneously.
This event represents at least the sixth incident of automatic shooting by frequency recorded in Havana so far in 2026, indicating that the system operates systematically at the limits of its capacity.
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