REXA Actuator - Steam Turbine Pilot Valve

Steam turbines control speeds/loads of generators and compressor, feedpump, and fan speeds. Speed instability and trips are often attributed to the pilot control actuator. These are usually small actuators supplied as part of a "governor control system". Since there is a hydraulic pressure readily available from the lube oil system, it is used to power the small hydraulic actuator (after passing through a "control oil" system). In order to control accurately these small actuators have small ports that are hyper-sensitive to particulate matter. Before oil goes to these actuators it must be filtered to extreme cleanliness levels. Extreme cleanliness requirement + inherently dirty oil system = Danger. This is the main reason that REXA actuators have been retrofit to so many steam turbines (Driven by any manufacturers governor control system that has an analog output signal). While retaining the controllability of a servo or proportional valve based hydraulic system, it does not require an external oil supply. It is a sealed, purged, closed-loop system with no oil tank, no filtration requirements and no periodic oil maintenance. The system shown has 100cc's of standard "off the shelf" motor oil. Although it is an inherently clean system it is not sensitive to particulate levels in standard motor oil. Particulate tolerant system + inherently clean closed loop system = high reliability. This is what REXA's technology offers.... Improved speed control, reliability, reduced maintenance and fire hazard. Control oil systems can be eliminated completely with REXA's broad product range for steam turbine applications (pilot valves, direct drives, rotary, linear, stop valve actuators, etc...)