Cuba’s electrical system collapsed Friday, as mounting problems with a lack of oil and dilapidated infrastructure reached a crisis point, paralyzing the economy of the Communist nation.The Energy and Mining ministry announced the “total disconnection” of the national electricity system at 11:07 a.m., after the Antonio Guiteras thermoelectric power plant in the city of Matanzas suddenly shut down. Authorities said they were scrambling to get the facility back online, but it was unclear when that might occur.Thursday night, Cuban authorities had already taken drastic steps to curb energy use, announcing the shutdown of schools, many government offices and entertainment sites like discos. Authorities ordered nonessential businesses to halt production.