Electric actuator
The advantages are easy access to energy, fast signal transmission speed, long transmission distance, easy centralized control, high sensitivity and accuracy, easy coordination with electric regulating instruments, and simple installation and wiring.
The disadvantage is that the structure is complex, the average failure rate is higher than that of the pneumatic actuator, which is suitable for places where explosion-proof requirements are not high and gas sources are scarce.
Circuit Design of Electric Actuator
1. Actuator is mainly used to control the driving device of driving valve. Simply speaking, it is to control the positive and reverse of the gate. First of all, the size of the actuator motor should be chosen according to the torque of the valve. The torque of the valve is generally between 1NM and 30000NM. The choice of the motor is also about 0.25KW-15KW. The motor under 3KW can be used. Contactors and thyristors are used to control, and contactors must be used to control those above 3KW.
2. According to the process requirements of the customer site, it is considered whether the door is switching or adjusting. If the door is adjusting, and the adjusting is very frequent, thyristor must be used. Because the dark contact of thyristor can be regarded as infinite use, and the service life of the contactor is 10,000,000 times.
3. Stopping mode is through limit stop of gate actuator, or moment stop. Each actuator must be equipped with limit switch and moment switch. If limit stop is used, moment switch is used as protection, and limit switch is used as protection when moment stop is used.
4. Switch-type electrical control mode is relatively simple. It can be said that Zui can be used as a simple positive and negative control circuit, while the regulated type needs potentiometer or Hall element as feedback, which can be designed with PLC or single chip computer.
5. If it is controlled by Profibus and other buses, it can be said that domestic actuators have not reached this level, and the technology of foreign actuators is very mature.
6. The mode of power supply can be chosen according to the power supply board. In China, 380V, or 220V, is basically used.
Guidelines for Selection of Electric Actuators
1. Determine the output torque of the electric actuator according to the torque required by the valve
The torque required for valve opening and closing determines how much output torque the electric actuator chooses. Generally, it is proposed by the user or selected by the valve manufacturer. As the actuator manufacturer, it is only responsible for the output torque of the actuator. The torque required for valve opening and closing normally is determined by the size of the valve caliber, working pressure and other factors, but because of the valve manufacturer. Home processing accuracy, assembly process are different, so the same specifications of the valve produced by different manufacturers need different torsion, even the same specifications of the valve manufactured by the same valve manufacturer also have different torsion, when the selection of actuator torsion is too small, it will cause the normal opening and closing of the valve, so the electric actuator must be. A reasonable range of torsion should be chosen.
2. Determining Electrical Parameters Based on the Selected Electric Actuator
Because the electrical parameters of different actuator manufacturers are different, it is generally necessary to determine their electrical parameters in design and selection, mainly motor power, rated current, secondary control circuit voltage, etc. Often negligent in this respect, the result is that the parameters of the control system and the electric actuator do not match, resulting in idle tripping and insurance at work. Faults such as wire fusing, thermal overload relay protection