Variable speed actuators enhance process control

Jon Lawson

Electric actuator manufacturer AUMA has added variable speed models to its proven SA actuator range, bringing significant advantages to power plant applications. With the new SAV actuators, each change of valve position can be done at the optimum speed. A wide speed control range of 1:10 allows both high speeds for rapid opening and closing and low speeds for maximum positioning accuracy.

Control valves, for example, can be operated at high speed during most of the valve travel. The speed can then be reduced progressively as the valve position approaches the setpoint, giving a significant increase in positioning accuracy.

Speed profiles can be tailored to specific valve requirements, avoiding pressure surges and cavitation. Configuration of soft start and soft stop behaviour minimises mechanical stresses on the valve, motor and gearbox.

Actuator speeds can be set independently for the open and close directions, and for emergency operation. Speed can also be controlled by an external signal to take advantage of additional control variables or algorithms.

The SAV multi-turn actuators are available for open-close duty, while SARV multi-turn actuators are for modulating duty. Both types can be supplied in six sizes covering torques up to 1,000Nm. Speed ranges include 6-60rpm, 12-120rpm and 24-240rpm. Explosion-proof versions are also available.