The power station was built by the central government in 1915, and started supplying the Landeskogen sanatorium with electricity the following year.
Longerak power station is situated in Bygland Municipality in Aust-Agder. The municipality has a population of 1,200, and covers an area of 1,312 km², approximately 12% of which is water. Longerak is one of three power stations in the municipality.
The power station lies half way up the valley side on the east side of Lake Byglandsfjorden.
The power station makes use of the 300-metre drop from the Langeraksvatn reservoir, which is dammed to an elevation of between 598 and 594 m above sea level.
Wikipedia, Agder Energi’s own data.