Selection of electric actuators

There are two types of  electric actuators, which are generally divided into partial rotary Electric Actuators and multi-turn Electric Actuators, the former mainly controls the valves that need to be partially rotated. For example: ball valves, butterfly valves, etc., the latter require valves with multiple turns of rotation, such as gate valves, globe valves, etc.
Electrically driven multi-turn actuators are one of the most commonly used and reliable types of actuators. A single-phase or three-phase motor is used to drive a gear or worm gear and worm to finally drive the stem nut, which causes the stem to move the valve to open or close. The multi-turn Electric Actuator can quickly actuate large valves. In order to protect the valve from damage, the limit switch installed at the end of the valve stroke will cut off the power supply to the motor, and when the safety torque is exceeded, the torque sensing device will also cut off the motor power supply, the position switch is used to indicate the switching status of the valve, and the handwheel mechanism installed with the clutch device can manually operate the valve when the power supply fails.
The main advantage of this type of actuator is that all components are housed in a single housing, which integrates all basic and advanced functions in a waterproof, dustproof and explosion-proof housing. The main disadvantage is that when the power supply fails, the valve can only be kept in place, and the valve can only achieve a fail-safe position (fault on or fault off) with a backup power system.
This actuator is similar to an electric multi-turn actuator, the main difference is that the final output of the actuator is 1/4 of the 90-degree motion. The new generation of electric single-turn actuators combines the complex functions of most multi-turn  actuators , such as parameterization and diagnostics using a non-intrusive, user-friendly operator interface. Single-turn actuators are compact enough to be mounted on small valves, typically with an output torque of up to 800 kgm, and with the small power required, they can be battery-mounted for fail-safe operation.