Electric devices are indispensable driving equipment for remote control, automatic control, and remote control of valves. The movement process of electric actuators can be controlled by the magnitude of stroke, torque, or axial thrust. Due to the working characteristics and utilization rate of valve electric devices, they depend on the type of valve, the operating specifications of the device, and the position of the valve on the pipeline or equipment.

電動裝置一般由下列部分組成：

Electric devices generally consist of the following parts:

專用電動機，特點是過載能力強﹑起動轉矩大﹑轉動慣量小，短時﹑斷續工作。

A specialized motor characterized by strong overload capacity, high starting torque, small moment of inertia, and short and intermittent operation.

減速機構，用以減低電動機的輸出轉速。

A reduction mechanism used to reduce the output speed of the motor.

行程控制機構，用以調節和準確控制閥門的啟閉位置。

The stroke control mechanism is used to adjust and accurately control the opening and closing position of the valve.

轉矩限制機構，用以調節轉矩(或推力)并使之不超過預定值。

Torque limiting mechanism, used to adjust torque (or thrust) and ensure that it does not exceed a predetermined value.

手動﹑電動切換機構，進行手動或電動操作的聯鎖機構。

Manual or electric switching mechanism, an interlocking mechanism for manual or electric operation.

開度指示器，用以顯示閥門在啟閉過程中所處的位置。

Opening indicator, used to display the position of the valve during the opening and closing process.

一、根據閥門類型選擇電動執行器

1、 Select electric actuators based on valve type

．角行程電動執行器（轉角<360度）適用于蝶閥、球閥、旋塞閥等。

Angular stroke electric actuators (angle<360 degrees) are suitable for butterfly valves, ball valves, plug valves, etc.

電動執行器輸出軸的轉動小于一周，即小于360度，通常為90度就實現閥門的啟閉過程控制。此類電動執行器根據安裝接口方式的不同又分為直連式、底座曲柄式兩種。

The rotation of the output shaft of the electric actuator is less than one cycle, which is less than 360 degrees, usually 90 degrees, to achieve valve opening and closing process control. This type of electric actuator can be divided into two types based on the different installation interface methods: direct connection type and base crank type.

直連式：是指電動執行器輸出軸與閥桿直連安裝的形式。

Direct connection type: refers to the form of direct connection installation between the output shaft of the electric actuator and the valve stem.

底座曲柄式：是指輸出軸通過曲柄與閥桿連接的形式。

Base crank type: refers to the form in which the output shaft is connected to the valve stem through a crank.

多回轉電動執行器（轉角>360度）適用于閘閥、截止閥等。

Multi turn electric actuators (angle>360 degrees) are suitable for gate valves, globe valves, etc.

電動執行器輸出軸的轉動大于一周，即大于360度，一般需多圈才能實現閥門的啟閉過程控制。

The rotation of the output shaft of the electric actuator is greater than one cycle, which is greater than 360 degrees. Generally, multiple cycles are required to achieve valve opening and closing process control.

二、根據生產工藝控制要求確定電動執行器的控制模式

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

開關型（開環控制）

Switch type (open loop control)

開關型電動執行器一般實現對閥門的開或關控制，閥門要么處于全開位置，要么處于全關位置，此類閥門不需對介質流量進行精確控制。

Switch type electric actuators generally achieve open or close control of valves. The valves are either in the fully open or fully closed position, and this type of valve does not require precise control of medium flow.

特別值得一提的是開關型電動執行器因結構形式的不同還可分為分體結構和一體化結構。選型時必需對此做出說明，不然經常會發生在現場安裝時與控制系統沖突等不匹配現像。

It is particularly worth mentioning that switch type electric actuators can be divided into split structure and integrated structure due to different structural forms. When selecting a model, it is necessary to explain this, otherwise mismatches such as conflicts with the control system during on-site installation may often occur.

分體結構（通常稱為普通型）：控制單元與電動執行器分離，電動執行器不能單獨實現對閥門的控制，必需外加控制單元才能實現控制，一般外部采用控制器或控制柜形式進行配套。 此結構的缺點是不便于系統整體安裝，增加接線及安裝費用，且容易出現故障，當故障發生時不便于診斷和維修，性價比不理想。

Split structure (usually referred to as ordinary type): The control unit is separated from the electric actuator, and the electric actuator cannot independently control the valve. It is necessary to add a control unit to achieve control. Generally, the external system is equipped with a controller or control cabinet. The disadvantage of this structure is that it is not convenient for the overall installation of the system, increases wiring and installation costs, and is prone to faults. When faults occur, it is not easy to diagnose and repair, and the cost-effectiveness is not ideal.

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