Electric actuation

The CVA electric actuator from Rotork is claimed will hold the setpoint, feature no deviation and will respond quickly to a change. Controlled by a 4–20 mA signal, the CVA is suitable for the direct-drive actuation of linear or quarter-turn control valves. The CVA demonstrates 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 ‘double-sealed’ enclosure, whereby internal electrical components are permanently protected from the effects of the operating environment.

The IP68 dust-tight, watertight and temporarily submersible (7 m, 72 h) enclosure is universal to all models in the CVA range, including those with hazardous area approvals. The CVA 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 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 utilises a new variant of Rotork’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 website.

Every CVA 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.