Mariazellerbahn is a narrow-gauge railway that runs from Sankt Pölten to Mariazell in Austria. Since 1911, Mariazellerbahn has run on a special frequency of electricity - single-phase AC of 25 hertz and 6300 volts.
Since electricity with these specific characteristics cannot be taken directly from the power grid, Mariazellerbahn has two hydroelectric generating stations that work solely to power the train. One generating station, which produces 4.5 megawatts of power, sits at Weinerbruck and the other, which produces 2.8 megawatts of power, is located in Erlaufboden. At Erlaufboden, a rotary converter allows for the conversion of three-phase AC from the public grid to single-phase AC of 25 hertz.
The electricity generated for Mariazellerbahn is transmitted from the generation stations to substations at Gosling and Raben stein by 27 kilovolt lines mounted on pylons.