Criteria for Selecting Electric Actuators

With the wide variety of types available, selecting the right electric actuator can be challenging; choosing an unsuitable product amidst a busy schedule is frustrating.

Here are the criteria for selecting electric actuators:

1. Operating Torque:

This is the primary parameter for selection. The output torque of the electric actuator should be 1.2 to 1.5 times the maximum operating torque of the valve.

2. Operating Thrust: There are two structural configurations for the main unit of an electric actuator:
One type does not include a thrust disc and outputs torque directly.
The other type includes a thrust disc, where the output torque is converted into output thrust via the stem nut located within the thrust disc.

3. Determining Electrical Parameters:
Electrical parameters vary among manufacturers, so they must be specified during the design and selection process. Key parameters include motor power, rated current, and control circuit voltage. Oversights in this area often lead to mismatches between the control system and the actuator, resulting in issues such as circuit breaker tripping, fuse blowing, or thermal overload relay activation during operation.

4. Matching Actuator Output Torque to Valve Requirements:
The torque required to open and close the valve determines the necessary output torque of the electric actuator. This requirement is typically specified by the user or determined by the valve manufacturer. While the actuator manufacturer is responsible only for the actuator's output torque, the torque required for valve operation depends on factors such as valve size and working pressure. However, variations in machining precision and assembly processes mean that torque requirements differ for valves of the same specification produced by different manufacturers-or even by the same manufacturer. If the selected actuator torque is too low, the valve cannot be operated correctly; therefore, a suitable torque range must be selected.