Electric actuators deliver reliable automation at renewable energy power plants

Louise Smyth

Applications at hydroelectric and geothermal power generation plants in North America illustrate the economical and flexible abilities of modern electric valve actuators in providing reliable automated solutions for turbine related duties.

Economical automation of flow to turbines
At the Alameda Hidroeléctrica Planta in Mexico, CK Range modular electric valve actuators from Rotork have provided an economical automated solution for controlling the flow of water to turbines that generate up to 6MW of electricity.

The modular CK design has enabled the operator to tailor the actuator specification to precisely match the requirements of the application. The selection of CK actuators complete with Centronik digital control units required only the provision of a mains electricity supply to provide automation of the previously hand-operated valves.

The Centronik control unit provides intelligent valve control with data logging for diagnostics and asset management. Rapid and secure commissioning and configuration is performed using selector switches on the Centronik housing or via a Rotork Bluetooth setting tool, following user-friendly menu driven screens displayed on the actuator indication window. In normal operation the window displays the valve position, valve status and alarms.

Standard features that are common to all CK actuators include a double-sealed IP68 (8m for 96 hours) enclosure for enhanced environmental protection, plug and socket connections for fast and efficient commissioning and maintenance, motor-independent handwheel operation, mechanical valve position indication and independent torque and position sensing for increased valve protection. Actuator gearboxes are oil lubricated for extended life and separable thrust or non-thrust bases enable actuators to be removed without disturbing the valve position.

Failsafe protection from turbine damage
At a geothermal power generation plant, Rotork electric valve actuators with battery powered failsafe back up have been installed to provide a simple, reliable and economical solution for turbine protection. Protecting the turbine from damage that might interrupt operations is essential, as the plant plays a key role in energy distribution in the surrounding area, providing clean renewable energy from a geothermal source.

In this application a Rotork IQT part-turn intelligent actuator equipped with an integral battery failsafe package operates a butterfly valve on a steam line. The battery backup provides electrical operation in the event of mains power loss. This allows the valve to be operated to a safe position or controlled for a period of up to 30 minutes, providing reliable and constant protection of the turbine. The batteries are charged when mains power is applied to the actuator.

In common with the CK actuators, Rotork IQ actuators feature IP68 double-sealed environmental protection to provide reliable operation in challenging ambient conditions, together with the data logging, diagnostic and asset management benefits inherent in Rotork intelligent valve actuation technology. IQ actuators are also available with explosion-proof certification for use in hazardous areas

Sarah Kellett is with Rotork

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