The underground cable that triggered the general blackout last December 31 was out of service prior to the breakdown, said this Friday LUMA Energy’s vice-president of Capital Projects, Juan Rodríguez, who could not specify, for the moment, how an equipment in that state could have caused an emergency of such magnitude.

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“That cable was completely out of service. We are investigating what happened. It was out of service and yet it still caused (the blackout). That’s what we are investigating,” said Rodríguez, accompanied by LUMA President Juan Saca, in a separate interview with the media after a press conference held by U.S. Energy Secretary Jennifer Granholm at the Miramar Convention Center.

The engineer, who acknowledged that failures with similar repercussions “can happen again” as long as the power grid remains as fragile as it is today, said that LUMA, with funds from the Federal Emergency Management Agency (FEMA), is heading projects aimed at replacing the cable that is responsible for the general blackout, an equipment that both Rodríguez and Saca said has exceeded its useful life.

“It is old equipment. This cable that broke down (...) we don’t know, because we don’t have all the records and we are searching, how old it is, but I can tell you that 25 years ago the company that manufactured that cable closed its doors. So (the cable is) at least 25 years old, but probably 40 or 50 years old”, said Saca.

Rodríguez estimated that the underground cable - which is part of the substation located in front of the Costa Sur power plant in Guayanilla - dates back to “1970 or a little further back”.

“That cable, when it fails, creates these disturbances. The fundamental problem is the design: a lot of generation going out through (the Costa Sur substation), and we don’t have redundancy in the electrical system in Puerto Rico. LUMA is working with that,” said Rodríguez, noting that an additional substation is planned for the area to handle the 230 kilovolt (kV) transmission lines coming from Costa Sur and the EcoEléctrica (Peñuelas) cogeneration plant.

Separately, Agustín Irizarry, professor of Electrical Engineering at the University of Puerto Rico Mayagüez Campus, said that LUMA’s explanation of the failure caused by an out-of-service line was difficult to understand: “It doesn’t make sense to me. I would like to understand what happened.

The switchyard where the failure was recorded on New Year day receives generation from both plants and has 230 and 115 kV lines, said Rodríguez.

“What we have detected to date, while the investigation continues, is that of the two 230 kV underground cables that connect the 230 kV switchyard to the 115 kV switchyard, one of them fails and causes a disturbance in the system. (Then) the 230 kV lines are protected, shut down, take the generation out of the system and the 115 kV (system) is overloaded. The design of the electric system in Puerto Rico is not modern. That cable is something that in my experience I had not seen. That run from one place to another (between switchyards) is not an optimal design,” insisted Rodríguez.

Last Tuesday, the Puerto Rico Energy Bureau initiated an investigation into the incident - which caused instability in service for more than 72 hours - and ordered LUMA to submit a preliminary report by January 15. Experts consulted by El Nuevo Día have emphasized that it is urgent to know why the electric system was unable to “isolate” the failure and, thus, prevent the output of all generation units.

Rodríguez, who oversees the formulation and execution of infrastructure projects, noted that LUMA has changed “at least” four circuit breakers at the Costa Sur substation, but that the replacement of equipment, in general terms, is delayed by delivery periods, which can fluctuate between two and three years.

Meanwhile, Saca welcomed the appointment of Josué Colón as Energy Czar and director of the Public-Private Partnerships Authority, positions from which he will oversee LUMA and Genera PR. As executive director of the Puerto Rico Electric Power Authority (PREPA) since 2021, Colón criticized LUMA’s management, which Saca dismissed by stating that the public corporation had no influence in the consortium’s decisions.

“The important thing is to move forward in Puerto Rico and I think that having this person, who was part of the entire PREPA scaffolding for many years, knows the system very well, knows very well (the component of) generation and the technical part, this will help a lot to move forward in Puerto Rico,” said the executive.

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This content was translated from Spanish to English using artificial intelligence and was reviewed by an editor before being published.