Ožbalt power plant: the more capable of the electric twins
The second power plant on the section of the Drava River between Vuzenica and Fala was built between 1957 and 1960 as the twin of the Vuhred HPP upstream.
The Ožbalt HPP, the fourth power plant in the Slovene section of the Drava River, takes advantage of the power potential of the Drava in the section between the Vuzenica and Fala Power Plants. The circumstances leading to the construction of the Vuhred Power Plant's twin enabled the simplification of a number of procedures, especially regarding equipment and construction works, resulting in faster completion. The construction of the plant began in 1957 and within three years two units were operating. Since the Ožbalt HPP has the same energy specifications as the Vuhred HPP, the pier type structure was also chosen.
After the refurbishment of the Upper Drava power plants in the nineteen nineties, the net capacity increased to 73,2 MW. The plant, with its increased power, makes use of a 17,42 available head, generating annually 305 million kWh of electricity.
The damming of the Drava River here resulted in a 12,7 km long reservoir containing 10,5 million m3 of water, of which 1,4 million m3 can be used for the generation of power. The dam structure itself is made up of three turbine piers placed between four spillways and the left and right bank buildings. The turbine piers accomodate vertical Kaplan turbines with generators above, connected via 10 kV cables to unit transformers located in the switchyard outside. All the equipment necessary for controlling the individual units is located in the turbine piers. In the middle of each 17 m wide spillway, a horizontal reinforced concrete girder is installed which separates the spillways into their upper and lower parts. The spillways are closed by the lower and upper spillway gates. The spilling capacity of all four spillways amounts to 5800 m3/s. A gantry crane is installed on the dam structure and is used for raising and lowering of heavier machinery and components. The outdoor switchyard is composed of double busbars with three unit transformers and three line bays attached to them.