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Working Principle of Electro Pneumatic Transducer
The working principle of the electro pneumatic transducer is shown in the figure. It is designed and works according to the principle of force balance. There is a coil inside. When the current signal of the regulator (transmitter) is sent to the coil, the coil and lever are displaced due to the action of the internal permanent magnet, which drives the baffle to approach (or move away from) the nozzle, causing the nozzle back pressure Increase (or decrease), this back pressure acts on the internal pneumatic power amplifier, the amplified pressure is used as the output of the converter, and the other is fed to the feedback bellows. The pressure delivered to the feedback bellows produces a reverse displacement on the other end of the iron core through the force transmission of the lever. When this displacement and the input signal produce an electromagnetic torque balance, the input signal and the output pressure have a one-to-one corresponding proportional relationship . That is, when the input signal changes from 4mA.DC to 20mA.DC, the output pressure of the I/P converter changes from 0.02~0.1MPa, and the process of converting the current signal into a pneumatic signal is realized. The zero adjustment mechanism in the picture is used to adjust the zero position of the converter, and the feedback bellows plays a feedback role.
The electric-pneumatic converter receives the 4-20mA direct current signal from DCS, and then proportionally converts and outputs the pneumatic signal of 20-100kpa, which is used as the pneumatic control signal of the pneumatic membrane regulating valve, pneumatic valve positioner and other pneumatic instruments. , It plays the role of signal conversion between electric instrument and pneumatic instrument.