Views: 203 Author: Site Editor Publish Time: 2021-04-27 Origin: Site
There are two types of electric actuators, generally divided into part-turn electric valve actuator and multi-turn electric valve actuator.
The former mainly controls valves that require partial rotation, such as electric ball valve, electric actuated butterfly valve, etc. The latter requires a valve with multiple turns, such as electric actuated gate valve.
Electric actuators generally have switch type and regulating type.
Switch-type electric actuators should have the following functions.
The output indicates the state signal of fully open, fully closed and at least one intermediate position.
When the load exceeds the maximum control torque, it outputs the torque overload status signal in the opening and closing stroke directions.
Output the remote flashing signal indicating the movement status.
Output resistance signal representing valve position or (4-20)m ADC current signal.
Adjustable electric actuators should have the following functions.
The output indicates the status signal of fully open and fully closed positions.
When the load exceeds the maximum control torque, it outputs the torque overload status signal in the opening and closing stroke directions.
Output (4^20)r nADC current signal representing the valve position, and its load capacity should not be less than 65052.
The motor should be equipped with thermal protection components.
An electric actuator equipped with a power control part should have the following functions.
Adjustable electric actuators should be able to accept the following types of input signals: (4 ^ 2 0) m A D C analog signal, input impedance no greater than 25052, 24VDC pulse signal, pulse width greater than 300ms and contact signal.
The switch-type electric actuator should be able to accept the following types of input signals: contact signal, 24VDC switch signal, realize remote and local operation control and switch between remote and local. In addition, the local operation control part must have protective measures to prevent misoperation.
Intelligent electric actuator should have the following functions.
All functions of the electric actuator equipped with power control part.
Parameter setting, debugging and fault diagnosis are carried out through the man-machine interface displaying various symbols, numbers, and characters.
Through dead zone adaptation or other methods, the high speed electric actuator does not oscillate under various operating conditions.
It prevents the motor from idling.
It automatically corrects the phase sequence of the input three-phase power.
When a fault occurs, it should stop at the original position and give a fault status signal.
The emergency operation valve has both closing and opening functions.
In order to successfully realize process automation, the most important thing is to ensure that the electric actuator valve itself can meet the special requirements of the process and the medium in the pipeline. Usually the production process and process media can determine the type of valve, the type of valve core, and the structure and material of the valve trim and valve.
When the electric actuator is matched with the valve, its control torque should meet the following conditions:
The maximum control torque output by the electric actuator should be greater than the torque required to open or close the valve when it is working.
The minimum control torque output by the electric actuator should be less than the torque required to open or close the valve in the working state.
The minimum control torque output by the regulating electric actuator should not be less than the operating torque of the regulating valve or regulating the middle position of the baffle.
When the electric actuator is matched with the valve, its rated stroke should meet the following conditions:
The rated stroke of the electric actuator should not be less than the maximum stroke of the valve.
The rated stroke range value of the electric actuator shall be adjustable.
Valves operating at two speeds should be matched with the following types of two-speed electric actuators, including double-motor electric actuators, pole-changing two-speed electric actuators, and variable frequency speed-regulating electric actuators.
