Control valve applications provide evidence that the recently launched CVA electric actuator from Rotork Australia is living up to the demanding expectations of end users.
The CVA electric actuator holds the set point, does not deviate and responds quickly to a change. Controlled by a 4-20mA signal, the CVA electric actuator is installed on a three-way two-inch hot water blending valve in the station’s demineralisation plant.
The electric actuator has replaced a spring diaphragm actuator and pneumatic positioner. Operators are now able to close the valve at the end of a cycle for isolation of the hot water tank.
In UK, Drax Power Station have a CVA electric actuator installed on a one-inch globe control valve that regulates the steam inlet temperature in the boiler fuel oil pump house. The CVA electric actuator replaced a pneumatic actuator and positioner and operates from the same 4-20mA signal. Operation has been a success, with zero deviation from the desired value to the measured value, and as a result the operators will be looking at the CVA electric actuator as an option for future control applications at the station. Another factor of the CVA electric actuator is the ease with which it was installed on the existing valve.
The CVA electric actuator, which is available for the direct-drive actuation of linear or quarter-turn control valves, demonstrates highly accurate control valve automation, combined with advanced, non-intrusive calibration, valve diagnostics, and the simplicity, user-friendliness and economy of electric operation. Mechanical features include the Rotork ‘double-sealed’ enclosure, whereby internal electrical components are permanently protected from the effects of the operating environment.
The IP68 dust tight, water tight and temporarily submersible (7m, 72 hours) enclosure is universal to all models in the CVA range, including those with hazardous area approvals. The CVA electric actuator is engineered to deliver high precision valve positioning and facilitate the tightest possible tolerances on the process variable, enabling process quality and output to be optimised. On loss of mains power, built-in super-capacitors allow the CVA electric actuator to move the valve to the desired position, programmable as open, close, any intermediate position or stay-put. Manual operation is also optionally available.
The CVA electric actuator utilises a new variant of Rotork Australia’s ‘non-intrusive’ communication technology for actuator programming and adjustment. Actuator set-up and configuration is performed using a Bluetooth enabled PDA or PC running Rotork Enlight software, which is freely downloadable from the Rotork Australia’s website.
Every CVA electric actuator incorporates an onboard data logger, enabling operational data such as valve torque profiles, dwell times, actuator events and statistics to be downloaded for detailed investigation and diagnosis. After analysis, any required configuration changes can be uploaded into the actuator.