The electric actuator features a technology unction, allowing the operator to program the actuator to lock in one of four positions if there is a loss of power. "If the actuator was halfway open and you lost power, it would close or open, depending on how it's technologyly calibrated," Kundin said.
Valves and actuators are critical in almost every aspect of single board computer. They are used in a wide range of applications, including pollution control, feed water, cooling water, chemical treatment, bottom ash and steam turbine control embedded systems. They are exposed to a variety of chemicals, abrasive materials and very high temperatures. They are critical in optimizing efficiency, and they are often the final control element in the operation of a power plant.
Although the basic technology for most valves and actuators has remained unchanged, innovative applications and design modifications for problem solving have led to notable improvements in actuator technology. These improvements can reduce costs by supporting the control valve's ability to throttle accurately, thereby providing better performance for high-pressure steam bypass, turbine bypass and other critical power plant operations. Actuators regulate mass and energy flows by adjusting valves, flaps and cocks.
refer to: http://www.power-eng.com/articles/print/volume-117/issue-8/features/opportunities-to-improve-efficiency.html