On Thursday, the San Geronimo B substation in the center of the country, which supplies electricity to four out of five Venezuelans from the massive Guri hydropower plant, went down. No date has been set to restart the plant and most workers were told to stay home on Monday ... Other experts, including Mr. Aguilar, said the magnitude of the blackout indicated the problem was caused by a major failure inside Guri’s turbines. A Corpoelec supervisor involved in dispatching Guri’s power said he was told by the plant’s managers on Thursday that the plant’s equipment was damaged. ... Mr. Aguilar...