Of the 32 main generators, 14 generators are on the north side of the dam. 12 are on the south side of the dam. 6 are in a separate powerhouse under a mountain just south of the dam. The generating capacity of the dam is 10,000 MWh (megawatt-hours), or the amount of megawatts generated per hour. Each main generator weighs a massive 6000 tons (about the same weight as three thousand cars). The water drops from the reservoir to the generator, which uses a type of turbine called a "Francis turbine". Each turbine is wide and tall. The amount of water that goes into the turbine can be from 1,968 cubic feet (600 m) to 3,116 cubic feet (950 m) per second. The turbines turn at a speed of 75 RPM (rotations per minute). The efficiency of the generators is from 94 to 96.5 percent.