How to Select the Electric Actuator?

From a traditional perspective, cylinders and electric actuators have always been regarded as automation products belonging to two completely different fields. With the continuous improvement of the degree of electrification, electric motor actuators are slowly immersed in the pneumatic field. The two are both competitive and complementary in applications.

 

Electric actuators are also called valve electric devices. It has different names in different industries. It is called valve electric device in the industrial pipeline valve industry, and it is called electric actuator in the instrument industry, but there is no clear distinction in the industry now.

 

Valves are frequently used important equipment in industrial pipeline control. With the development of industrial automation, electrically operated valves are more commonly used than air powered actuators, hydraulic actuators and other equipment with different driving methods because of their easy access to power source and the advantages of no maintenance in general.

 

Electric valves must have higher reliability and safety in industrial situations. When the valve can guarantee performance and life, the safety and reliability of the electric valve depends on the electric actuator. Therefore, the performance and control level of the electric actuator is the comprehensive performance of the overall technical level of the electric valve. Therefore, in addition to some basic elements that must be considered when selecting electric actuators, reasonable technical requirements can be put forward to maximize the value of electric valves.

 

Rotary valves require the required torque to perform a 90-degree rotation of the actuator, including plug valves, ball drip valves, motorized butterfly valves, etc. Multi-turn valves mainly include straight-through valves (stop valves), plug gate valves, knife gate valves, etc.

 

There are many types of electric actuators, such as electric linear actuator, electric rotary actuator and motor operated valve actuator. Different types and functions of electric actuators can be called electric valves when matched with valves. But often in the process of design and selection, only the parameters of the valve are ignored or the relevant requirements of the electric actuator are not clear. This not only prevents the electric valve from exerting its best performance, but also brings unnecessary troubles during installation, debugging and use, and even causes serious consequences for production.

 

Key Considerations for Electric Actuator Selection

 

1. Rotary electric actuator. The rotation of the output shaft of the electric actuator is less than 360 degrees, usually 90 degrees to achieve the valve opening and closing process control. This type of electric actuator is divided into two types: direct connection type and base crank type according to the different installation interface methods. This type of electric actuator is suitable for butterfly valves, ball valves, plug valves, etc.

 

2. Multi-turn electric actuator. The rotation of the output shaft is greater than 360 degrees. Generally, it takes multiple turns to control the opening and closing process of the valve.

 

3. Straight stroke. The motion of the output shaft of the electric actuator is linear motion, not rotating. This type of electric actuator is suitable for single-seat control valves, double-seat control valves, etc.

 

Determine the control mode of the electric actuator according to the production process control requirements

 

The control modes of electric actuators are generally divided into two categories: switch type (open loop control) and regulation type (closed loop control). Switch-type electric actuators generally realize the opening or closing control of the valve. The valve is either in the fully open position or in the fully closed position. This type of valve does not require precise control of the medium flow. The regulating electric actuator not only has the function of an on-off integrated structure, it can also accurately control the valve to precisely adjust the medium flow.

 

In addition, the control mode of the electric actuator is determined according to the control requirements of the production process.

 

The control modes of electric actuators are generally divided into two categories: switch type (open loop control) and regulation type (closed loop control). Switch-type electric actuators generally realize the opening or closing control of the valve. The valve is either in the fully open position or in the fully closed position. This type of valve does not require precise control of the medium flow. The regulating electric actuator not only has the function of an on-off integrated structure, it can also accurately control the valve to precisely adjust the medium flow.