The electric actuator comes with an integrated positioner. The movement of the actuator stem follows a continuous signal from 0/4 to 20 mA or 0/2 to 10 V. This allows a better control accuracy to be achieved compared to the three-step signal. Additional features (e.g. adjustable stroking speed, reversal of the direction of action, and blocking protection) allow the actuators with integrated positioner to be customized easily to your application.
A three-step version of the actuators are also available. This basic actuator version is used in applications where only normal requirements are placed on the control accuracy of the electric control valve.
The functions of an electric actuator with integrated positioner and an input-connected digital controller have been combined into one unit in the TROVIS electric actuators with process controllers. Signals from the ready-wired sensors are processed directly in the actuator depending on the control function that has been configured. The actuators can be used in heating and cooling applications as well as in domestic hot water (DHW) systems.
SAMSON offers different actuator types in different versions to match the wide valve range. Small valves in DN 15 as well as large valves in sizes up to DN 300 can be fitted with electric actuators. Small valve sizes with small rated travels require small actuator thrusts to hold the closure member in the closed position when the valve is closed, for large valve sizes with large rated travels, large actuator thrusts are required. This is why SAMSON offers a wide variety of actuators, which generate the force needed to safely close a valve depending on its size but without deforming the actuator stem or damaging the closure member and valve seat.
The requirements placed on how fast a valve opens and closes vary from process to process. The decisive factors that influence the time a valve needs to achieve the required control signal are the actuator’s response time and the actuator stem’s stroking speed. All SAMSON electric actuators come with fast response times. Only the stroking speeds can be selected:
If fastest transit times are required for highest control accuracy or for immediate fail-close action, actuators versions that include a fast motor are the prime choice.
If the process does not require fast stroking speeds, there is no need for a fast, high-performance motor.
In some actuator versions, it is possible to adapt the transit time. It can be adjusted in several steps.
In control loops where higher safety requirements apply, the control valve must be fully closed or opened when a hazardous event occurs. This is why electric actuators are fitted with a mechanical spring mechanism, which retracts or extends the actuator stem when the springs are relieved of pressure to safely close or open the valve. This is the major difference between actuators with and without fail-safe action: in actuators without fail-safe action, the actuator stem remains in its last position when the supply voltage fails. To guarantee that the valve reaches its fail-safe position in an emergency, the positioning force of the safety springs and the transit time for fail-safe action are perfectly tuned to one another.
SAMSON focuses on the operator. As a result, electric actuators offer maximum convenience in terms of operation:
Electric actuators are subject to numerous requirements that vary considerably depending on the application. In cases where the standard actuator version cannot meet the control demands, SAMSON electric actuators can be fitted with an extensive range of optional accessories.
The SAMSON product range includes special control and sensor accessories for the electric actuators with process controllers that have proven reliable and useful in heating, cooling and DHW applications. They make it significantly easier to engineer the control loop and start up the control valve.
