Hydro power is produced by the 1929 Gilkes 27hp turbine which is belt-coupled to a 20kW alternator. The current gearing runs the turbine at about 180rpm, well below the optimum 400rpm, which limits the maximum power to about 12kW. Hydro systems need to run at constant power for a given rotational speed (necessary to produce 50Hz AC) and water flow. To ensure that the alternator has a constant load a GP Electronics Electronic Load Controller passes any unwanted power into a ballast load. At Burton Mill the ballast load is an electric boiler in the central heating system with a reserve ballast load for emergencies.
Power data from the FITs meter: