Rotork electric valve actuators are contributing to a renewable energy refurbishment programme at a power station owned by South West Water. Opened in 1932, the plant at Mary Tavy is still England’s largest hydroelectric power station, working with smaller stations at nearby Morwellham and Chagford to produce a total of 3340kW of electricity from the water resources of Dartmoor. When the plants were acquired by South West Water in the 1990s, they were still largely operating with their original 70-year-old turbines, switchgear and gauges. As such they represent an important piece of industrial archaeology, attracting regular visits from educational, institutional and engineering groups. South West Water has therefore embarked on a programme to improve efficiency without altering the authentic overall appearance of the plant and machinery. The GBP 850,000 project entails the installation of new turbine wheels, modern switchgear and valve actuation, and the introduction of automated site control under PLC supervision. Nine Rotork electric actuators are being retrofitted at Mary Tavy, replacing manually operated equipment to control and govern the flow rate of water into the three Pelton wheel and three Francis wheel turbines on the site, an operation that used to require constant manual attention. Six Rotork IQM modulating actuators will continuously alter the position of the original linear water inlet valves in response to signals received from the PLC. Three Rotork actuators with DC motors and Rotork-designed battery control panels are also installed to automatically shut the main inlet gate valves to the turbines in the event of a power failure or similarly important alarm. Actuator installation is an integral part of the turbine refurbishment contract that has been awarded to the turbines’ original manufacturer, Gilbert Gilkes and Gordon.