The valves are widely used in various fields of national economy and people's livelihood. Because they need to adapt to the requirements of various working conditions, they have a wide variety and a large number. China's electric actuator manufacturing industry is very large, with thousands of valve manufacturers all over the country. At present, China has become one of the countries with large valve output and market demand in the world. However, most of the valve industries in China are small and medium-sized enterprises, with mixed advantages and disadvantages. There are less than 10 enterprises with an annual output value of more than 100 million yuan. Even compared with other domestic machinery industries, there is a big gap in terms of equipment and technical level. There are few units with independent research and development capacity. Therefore, in large petrochemical, nuclear power, oil and gas long-distance pipeline and other major projects, supporting valves are mainly imported at present.

对于执行机构广泛的定义是：一种能提供直线或旋转运动的驱动装置，它利用某种驱动能源并在某种控制信号作用下工作。执行机构使用液体、气体、电力或其它能源并通过电机、气缸或其它装置将其转化成驱动作用。

The actuator is widely defined as a driving device that can provide linear or rotary motion, and it uses some driving energy and works under the action of some control signal. The actuator uses liquid, gas, electricity or other energy sources and converts them into driving action through motors, cylinders or other devices.

阀门电动装置基本类型有部分回转(Part-Turn)、多回转(Multi-Turn)及直行程(Linear)三种驱动方式。

The basic types of valve electric device include three driving modes: part turn, multi turn and linear.

阀门电动装置可分为直行程和角行程两大类，它是自动控制系统中不可缺少的重要设备，其主要任务是将调节器送来的控制信号成比例地转换成直线位移或角位移去带动阀门、挡板等调节机构，以实现自动控制。因而广泛用于电力、冶金、石油、化工等工业部门的自动控制领域。

The electric valve device can be divided into two categories: straight stroke and angular stroke. It is an indispensable and important equipment in the automatic control system. Its main task is to convert the control signal sent by the regulator into linear displacement or angular displacement in proportion to drive the valve, baffle and other regulating mechanisms to achieve automatic control. Therefore, it is widely used in the automatic control field of electric power, metallurgy, petroleum, chemical and other industrial sectors.

近10年来，由于广泛采用和吸收微计算机控制、微机械等新技术、新成果与成熟经验，阀门电动装置得到迅速发展，现已广泛使用“微机+随动系统”结构模式的微机型阀门电动装置，由微处理器完成信号传递、调节参数切换、状态指示、控制量的输出，以提高调节性能、使用及维护保养等方面的灵活性。

In the past 10 years, due to the extensive adoption and absorption of new technologies, new achievements and mature experience such as microcomputer control and micromachining, the valve electric device has developed rapidly. Now, the microcomputer type valve electric device with the structure mode of "microcomputer+servo system" has been widely used. The microprocessor completes the signal transmission, adjustment parameter switching, status indication and control quantity output to improve the regulation performance Flexibility in use and maintenance.

阀门电动装置的可靠性是指它在规定的条件下、规定时间内完成规定功能的能力。

The reliability of valve electric device refers to its ability to complete specified functions under specified conditions and within specified time.

“规定的条件”一般可概括为：

The "specified conditions" can generally be summarized as:

(1)环境条件：指能影响阀门电动装置性能的环境特性，如温度、湿度、气压、磁场、机械冲击、振动、粉尘等。

(1) Environmental conditions: refer to the environmental characteristics that can affect the performance of the valve electric device, such as temperature, humidity, air pressure, magnetic field, mechanical shock, vibration, dust, etc.

(2)动力条件：指能影响阀门电动装置性能的动力特性。

(2) Dynamic condition: refers to the dynamic characteristics that can affect the performance of the valve electric device.

(3)负载条件：指能影响阀门电动装置性能的负载特性，如力矩、被控对象的类型与特性等。

(3) Load condition: refers to the load characteristics that can affect the performance of the valve electric device, such as torque, type and characteristics of controlled objects, etc.

(4)使用和维护条件：阀门电动装置的可靠性只有在使用中得以实现，并在维护中得到提高，对于使用和维护条件而言，要注意的是完善的使用和维护保养；其次是要求操作者达到相应的技术水平。

(4) Use and maintenance conditions: the reliability of valve electric device can only be realized in use and improved in maintenance. For use and maintenance conditions, the first thing to pay attention to is perfect use and maintenance; Secondly, the operator is required to reach the corresponding technical level.

“规定的条件”是阀门电动装置可靠性定义中重要而又容易忽略的部分。不同条件下，其可靠性是绝然不同的，离开具体条件谈可靠性将毫无意义。而“规定的功能”是表征阀门电动装置完成任务的各参量，如力矩、开/关及时间、行程、不动时间、死区等。

"Specified condition" is an important and easily ignored part in the definition of reliability of valve electric actuator. Under different conditions, its reliability is absolutely different. It is meaningless to talk about reliability without specific conditions. The "specified function" refers to the parameters representing the completion of the task of the electric valve device, such as torque, opening/closing and time, stroke, immobility time, dead zone, etc.