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[Gas valve positioner] Will the working principle of intelligent valve positioner?

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[Gas valve positioner] Will the working principle of intelligent valve positioner?

Release date:2017-08-25 Author: Click:

[Gas valve positioner] Will the working principle of intelligent valve positioner?

The entire control loop from the two lines, 4 ~ 20mA signal control. The HART module sends and receives digital information superimposed on the 4 ~ 20mA signal to enable bi-directional digital communication with the microprocessor. Analog 4 ~ 20mA signal to the microprocessor, and the valve position sensor feedback comparison, the microprocessor according to the size and direction of the deviation control calculation (level control), to the piezoelectric valve issued to the electronic control instructions to make it To open and close the action.

The piezoelectric valve according to the width of the control command pulse corresponds to the incremental output of the pneumatic amplifier, while the output of the pneumatic amplifier is fed back to the internal control loop, again with the microprocessor results of the comparison operation (secondary control), through Two-stage control output signal to the actuator, the actuator air pressure changes the control of the valve stroke. When the control deviation is large, the piezoelectric valve sends a wide pulse signal, so that the positioner output a continuous signal, a significant change to the actuator signal pressure to drive the valve fast action; with the valve close to the required position, the command required The difference between the position and the measured position becomes smaller, the piezoelectric valve outputs a pulse signal with a smaller pulse width, intermittently and slightly changes to the actuator signal pressure, so that the actuator moves closer to the new command position. When the valve reaches the desired position (into the dead zone), the piezoelectric valve has no pulse output, the positioner output remains zero, so that the valve is stable at a certain position.


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