capacitance Differential pressure transmitter
The transmitter is mainly composed of a detection part and a signal conversion and amplification processing part.
The detection part is composed of a detection diaphragm and fixed arc plates on both sides. The detection diaphragm can move axially under the effect of pressure difference to form a movable capacitor plate, and it is composed of two variable capacitors C1 and a fixed arc plate. C2, structural and electrical principles can be seen in Figure 6-11.
Before the test, the pressure balance between the high and low pressure chambers is P1 = P2. According to the structural requirements, the fixed arc plates and the detection membranes that make up the two variable capacitors are symmetrical and the pole spacing is equal. C1 = C2.
When the measured pressure P1 and P2 respectively enter the high and low pressure chambers through the inlet pipe, the center of P1 > P2 diaphragm will be displaced, and the electrolyte will compress the electrolyte to make the volume of the high pressure side smaller. When the electrolyte is an incompressible body, its volume change will cause the displacement of the center of the detection membrane to the low pressure side, and this displacement amount is equal to the center displacement of the isolation diaphragm. According to electrotechnics, when the distance between two pole plates that make up a capacitance changes, its capacitance will also change, from C1=C2 to C1 to C2.