Principle of mechanical positioner

     The valve positioner (generally a pneumatic valve positioner) is the main accessory of the control valve. It is usually used in conjunction with the pneumatic control valve. It receives the output signal of the regulator, and then uses its output signal to control the pneumatic control valve. When the control valve acts Later, the displacement of the valve stem is fed back to the valve positioner through the mechanical device, and the valve position status is transmitted to the upper system through electrical signals.

     The valve positioner is the main accessory of the control valve. It uses the valve stem displacement signal as the input feedback measurement signal, and the controller output signal as the setting signal for comparison. When there is a deviation between the two, it changes its output to the actuator The signal causes the actuator to act, establishing a one-to-one correspondence between the valve stem displacement times and the controller output signal. Therefore, the valve positioner constitutes a feedback control system that uses the displacement of the valve stem as the measurement signal and the output of the controller as the setting signal. The manipulated variable of the control system is the output signal from the valve positioner to the actuator.