Views: 220 Author: Site Editor Publish Time: 2022-07-18 Origin: Site
With the development of industrial automation, the role of electric actuator in automatic control system is becoming more and more important. How to choose the electric actuator correctly plays a significant role in improving the reliability, safety and economy of the whole automatic control system. Now the types of electric actuators on the market are gradually increasing, which leads to many problems for enterprises and users in the process of selecting and matching electric actuator with valve. The most direct consequences is to bring serious safety hazards in production.
When people purchase, they usually only focus on the parameters of the valve, but with little requirements for the electric actuator. If the electric valves used in the control system are different types of electric actuators and valves, improper matching will reduce the performance of the electric valves, cause trouble for later diagnosis and maintenance, and even cause safety failures.
Valve is an essential control mechanism for the transportation of fluid in the pipe network. It has been widely used in the industrial production of petroleum, chemical industry, power station, offshore crude oil exploitation, nuclear industry and so on. In the control of valves, with the development of industry, it is not only a simple on-off control, but also involves opening control, flow control and other relationship control.
The traditional manual mechanical regulation method can no longer meet the requirements in many occasions. There are many shortcomings in function and use, such as huge equipment, unreasonable mechanism matching, low control accuracy, poor safety, lack of perfect fault handling and alarm devices, The defects of not realizing man-machine dialogue well, being difficult to calibrate and maintain on site, and not conducive to the renewal and replacement of valve products are exposed more and more obviously. In order to improve the control performance of valve and pipeline system and improve the management level of industrial automation system, intelligent valve electric actuator came into being.
The requirement of electric valve for electric actuator is to be able to automatically adjust the opening and closing of the valve. We should choose electric actuators according to the requirements of field control. The control modes of electric actuators are generally divided into switch type (open-loop control) and regulation type (closed-loop control).
The switch type electric actuator generally realizes the opening or closing control of the valve, that is, the valve is either in the fully open position or in the fully closed position. Such valves do not need to accurately control the medium flow.
The regulating electric actuator not only has the function of switching, but also can accurately control the valve, so as to accurately regulate the medium flow. Control signals include voltage and current. Common control signals include voltage signal (0 ~ 5V, 1 ~ 5V) and current signal (4 ~ 20mA, 0 ~ 10mA). In projects that require high process accuracy, the pressure or water flow of the automatic control system will have a great impact on the production conditions, which is suitable for the use of adjustable electric actuators. In case of loss of control signal caused by line fault, it can be opened and closed to the set protection value. Therefore, when selecting electric actuators, it is necessary to clarify the parameters and types of control signals, which is the working form of adjustable electric actuators. However, in reality, many products cannot be modified after leaving the factory, so it is necessary to select the appropriate actuator parameters and types at the time of purchase.
The first thing to be determined is the maximum operating torque of the valve. Valve operating torque refers to the torque required when the valve is opened or closed, which is related to the structural form, diameter, working pressure and friction coefficient of the valve. Then the output torque of the electric actuator is determined according to the torque of the valve. The torque required for the opening and closing of the valve determines the output torque of the electric actuator.
Output torque is an important parameter of electric actuator, and the specific value can be obtained through the calculation formula of power and speed. It is worth noting that in practical application, the influencing factors such as operating pressure, temperature, medium density and viscosity tend to fluctuate, resulting in great changes in the opening and closing force and torque of the actual valve. And the torque required at the moment of opening and closing the valve is greater than that required in long-term operation.
Although the operating torque of the valve is less than the starting torque, it is still necessary to ensure that the operating torque is greater than the torque of the valve when selecting the electric actuator. Only in this way can the normal operation of the valve be guaranteed. Therefore, a reasonable torque range must be selected for the electric actuator. In order to meet the requirements of stable work, the output torque is generally reserved with a safety factor of at least 1.2~1.5 times.
MTD electric valve company's experienced engineers can provide buyers with free type selection consultation and customized services for the complete set of electric valve automation system. We will select the model of the appropriate electric valve according to your project needs to ensure the feasibility and safety of the automation system.
Electric closed valve is an electric one-way valve. When the closed valve is not powered, it is pressed by a strong spring and will not open due to the reverse air flow. Effectively guarantee the tightness of the corresponding space.
MTD Actuator Valve Inc. （exported by Ningbo leadwin international trade）specialized in manufacturing electric actuators, Valve accessories and automated products. We have a first-rated team composed of professional research, management and sales.
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