Electric Actuator Diagram & Working Principle - Wuxi Xinming Auto-Control Valves Industry Co., Ltd

Electric actuators are essential components in modern automation systems, converting electrical energy into mechanical motion. These devices play a crucial role in industrial automation, HVAC systems, robotics, and numerous other applications where precise motion control is required. This comprehensive article explores the fundamental working principles, internal components, and operational characteristics of electric actuators through detailed diagrams and technical explanations.

1. Basic Components of Electric Actuators

Figure 1: Electric Actuator Block Diagram

Electric actuator block diagram showing major components

The primary components of a typical electric actuator include:

Electric Motor: The power source that converts electrical energy into rotational mechanical energy. Common types include AC motors, DC motors, and stepper motors.
Gear Mechanism: Reduces motor speed while increasing torque output to move the load. Planetary gears, worm gears, and spur gears are commonly used configurations.
Lead Screw/Ball Screw: Converts rotational motion into linear motion through threaded components. Ball screws offer higher efficiency and precision compared to lead screws.
Position Sensor: Provides feedback about the actuator's position, typically using potentiometers, encoders, or resolvers.
Limit Switches: Mechanical or electronic switches that prevent over-travel beyond designed operational limits.
Control Electronics: Includes motor drivers, controllers, and communication interfaces for system integration.

2. Working Principle of Electric Actuators

The fundamental operation of electric actuators follows these sequential steps:

The control system sends an electrical signal (either analog or digital) to the actuator's control electronics.
The control electronics process the input signal and generate appropriate power signals for the electric motor.
The electric motor converts electrical energy into rotational mechanical energy.
The gear mechanism modifies the motor's output characteristics (speed and torque) to match application requirements.
The lead screw or ball screw converts rotational motion into linear displacement.
Position sensors provide continuous feedback to the control system for closed-loop operation.
Limit switches prevent mechanical damage by stopping motion at predefined travel limits.

Figure 2: Motion Conversion in Electric Actuators

Motion conversion process in electric actuators

3. Types of Electric Actuators

Electric actuators can be classified based on their motion type, motor technology, and control method:

Classification	Types	Characteristics
By Motion Type	Linear, Rotary, Multi-axis	Linear actuators produce straight-line motion, rotary actuators produce angular motion
By Motor Technology	AC, DC, Stepper, Servo	AC for high power, DC for precise control, stepper for open-loop positioning
By Control Method	On/Off, Modulating, Smart	On/Off for simple applications, modulating for proportional control

4. Performance Characteristics

Key performance parameters of electric actuators include:

Stroke Length: Maximum travel distance for linear actuators or rotation angle for rotary actuators.
Load Capacity: Maximum force or torque the actuator can generate.
Speed: Linear speed (mm/s) or rotational speed (rpm).
Positioning Accuracy: Minimum incremental motion and repeatability.
Duty Cycle: Operational time versus rest time ratio.
Protection Rating: IP rating indicating environmental protection level.