How to deal with common faults of electric control valves?

Electric control valve is an important executive unit instrument in industrial automation process control. The structure is composed of an electric actuator and a regulating valve connected and assembled through mechanical connection, assembly, debugging and installation to form an electric regulating valve. Below we will introduce you to the structure and principle of the electric control valve, common faults and treatment methods

 

 

The structure and working principle of electric control valve

1. Basic structure of electric control valve

The upper part of the electric control valve is the actuator, which accepts the 0～10mADC or 4～20mADC signal output by the regulator, and converts it into the corresponding linear displacement, which pushes the lower regulating valve to act and directly regulates the flow of fluid. The pneumatic actuator of various types of electric control valves are basically the same, but the structure of the control valve (regulation mechanism) varies in different types of use conditions, and the most commonly used are two-way through single valve seat and through two-way valve seat.

 

2. Controller structure

The controller consists of a main control circuit board, sensors, operating buttons with LEDs, split-phase capacitors, and wiring terminals. The intelligent servo amplifier is based on a dedicated single-chip microprocessor, which converts analog signals and valve position resistance signals into digital signals through an input loop. The microprocessor uses artificial intelligence control software according to the sampling results to display the results and output control signals.

 

3. The basic structure of the regulating valve

The regulating valve is in direct contact with the adjusted medium in the process pipeline, and the valve core moves in the valve body, changing the flow area between the valve core and the valve seat, that is, changing the resistance coefficient of the valve to adjust the process parameters.

 

 

Common faults and solutions of electric control valves

Fault 1: The actuator does not work, but the control module power and signal lights are both on.

Solution: Check whether the power supply voltage is correct; whether the motor is disconnected; whether the ten-core plug is disconnected from the end to the end of each line; whether the plugs of the motor, potentiometer, and capacitor are in good condition; use the contrast interchange method to determine whether the valve control module is good.

 

Fault 2: The actuator does not work, the power light is on but the signal light is off.

Solution: Check whether the input signal polarity is correct; use the contrast interchange method to determine whether the control module is good.

 

Fault 3: Improper adjustment of system parameters causes frequent actuator oscillation.

Solution: Improper parameter setting of the regulator will cause the system to produce varying degrees of oscillation. For a single-loop regulation system, if the proportional band is too small, the integral time is too short, and the differential time and differential gain are too large, system oscillation may occur. These parameters can be selected reasonably by the method of system tuning to keep the loop at a stable speed.

 

 

Have you encountered any failures in using pneumatic actuated valves and electric actuated valves? Welcome to discuss and resolve with us.