The electric valve actuator is powered by 220VAC/380VAC or other voltages, with 0 ~ 10V or 4 ~ 20mA D.C control signals and outputs rated torque and angular displacement corresponding to the control signals. It is mount on valves and dampers. The electric actuator we use now is basically composed of two parts: power components and position locator. Among them, the power components are mainly composed of motors, speed reducers, torque stroke limiters, switch control boxes, hand wheels and mechanical limit devices, and position transmitters. The functions of the electric actuators are briefly described as follows:
1. Motor: The motor is a special single-phase or three-phase AC asynchronous motor with high starting torque, low starting current and small rotational inertia, so it has good servo characteristics.
2. Reducer: The electric actuator with angular stroke adopts planetary deceleration plus turbine worm gear transmission mechanism, which has both high mechanical efficiency and mechanical self-locking characteristics. The reducer of the straight-stroke electric actuator is composed of a multi-turn electric actuator reducer and a screw nut transmission device.
3. Torque travel limiter: it is a standard unit installed in the reducer, which is composed of over-torque protection mechanism, travel control mechanism (electrical limit), position sensor and wiring terminals.
4. Switch control box: PM electronic position locator is installed in the switch control box.
5. Handwheel: In the fault state and debugging process, manual on-site operation can be realized by turning the handwheel.
6. Mechanical limit device: It is mainly used for protection in case of failure and to prevent exceeding the limit position during manual operation. The mechanical limit of the electric actuator adopts a built-in fan-shaped turbine limit structure, which has a small size and reliable limit; the mechanical limit of the straight-stroke electric actuator adopts a built-in stop type limit structure, which can effectively protect the valve seat and valve Rod, spool.