What Is An Electric Actuator?

An electric motor actuator can provide a linear or rotational drive device, which uses a certain driving energy and works under a certain control signal. The actuator uses liquid, gas, electricity or other energy and converts it into a driving function through a motor, cylinder or other device. The basic types include three driving methods: part turn electric actuator, multi turn electric actuator and electric linear actuator.

 

Electric actuators, like air powered actuators, are an important part of the control system. It receives the 4-20mA or 0-10mA DC current signal from the controller, and converts it into the corresponding angular displacement or linear displacement, to manipulate the valve, baffle and other control mechanisms to realize automatic control.

 

Electric actuators are available in linear, angular and multi-turn types. The angular stroke electric actuator uses the motor as the power element to convert the input DC current signal into the corresponding angular displacement (0 degrees to 90 degrees). This type of actuator is suitable for manipulating rotary control valves such as butterfly valves and baffles.

 

The electric linear valve actuator receives the input DC current signal and rotates the motor, then it is decelerated by the reducer and converted into a linear displacement output to manipulate various control valves such as single-seat, double-seat, three-way, and other linear control mechanisms.

 

Multi-turn electric actuators are mainly used to open and close multi-turn valves such as gate valves and globe valves. Because its motor power is relatively large, the largest is tens of kilowatts, and it is generally used for local control and remote control. These three types of actuators are all position servo mechanisms powered by two-phase AC motors. The electrical principles of the three are exactly the same, but the reducer is different.

 

The rotary electric actuator has the following main performance indicators. The input signal of the three-terminal isolated input channel is 4-20mA (DC), and the input resistance is 250 ohms. The output torque is 40, 100, 250, 600, 1000N·m. The basic error and variation are less than ±1.5%. The sensitivity is 240μA.

 

The motorised actuator is mainly composed of a servo amplifier and an actuator, and the operator can be connected in series. The servo amplifier receives the control signal sent by the controller and compares it with the feedback signal of the output displacement of the electric actuator. If there is a deviation, after the difference is amplified by the power, the two-phase servo motor is driven to rotate. Then the speed reducer will drive the output shaft to change the rotation angle. If the difference is positive, the servo motor rotates forward and the output shaft angle increases. If the difference is negative, the servo motor reverses and the output shaft angle decreases. When the difference is zero, the servo amplifier outputs a contact signal to stop the motor. At this time, the output shaft is stabilized at the corner position corresponding to the input signal. This kind of position feedback structure can make the linear relationship between input current and output displacement better.

 

The high speed electric actuator and electric piston actuator can not only cooperate with the controller to realize automatic control, but also realize the mutual switching between automatic control and manual control of the control system through the operator. When the switch of the manipulator is placed in the manual operation position, the positive and negative operation buttons directly control the power of the motor to realize the forward or reverse rotation of the output shaft of the actuator for remote manual operation.