The principle of capacitance pressure transmitter and classification
principle of capacitance pressure thermocouple sensor
it usually adopts the round metal film or metallized film as a capacitor electrode, when the film feel stress and deformation of thin film and formed between the fixed electrode capacitance change, by measuring the circuit can output and voltage into a certain relationship of electrical signals. Capacitance pressure thermocouple sensor belongs to the pole pitch change thermocouple type capacitance sensor, can be divided into single capacitive pressure thermocouple sensor and differential capacitive pressure thermocouple sensor.
capacitance pressure thermocouple sensor classification
single capacitive pressure thermocouple sensor
it made up of circular membrane with fixed electrode. Thin film under the action of stress, deformation and change of capacitor capacity, its sensitivity is roughly proportional to membrane area and the pressure and film tension and film to the fixed electrode is inversely proportional to the distance. Another type of fixed electrode concave spherical shape, diaphragm for fixed tension surrounding the plane, diaphragm are made from plastic metallized layer methods. This type is suitable for measuring low pressure, and have high overload capability. Can also be used with the piston moving very diaphragm made of measuring high pressure single capacitive pressure sensor thermocouple. This kind of pattern can reduce the direct compression area of the diaphragm, in order to use thin diaphragm improve sensitivity. It also with a variety of compensation and protection, and amplifying circuit overall package together, in order to improve the anti-interference ability. The thermocouple sensor for measuring dynamic high pressure and the aircraft telemetry. The single capacitance pressure thermocouple sensor and microphone type ( The receiver type) Such as type and stethoscope model.
the differential capacitance pressure thermocouple sensor
it's pressure diaphragm electrode is located between two fixed electrode, constitute two capacitors. In the stress under the action of a capacitor capacity increase corresponding decreases, and the other output measurements by differential circuit. It's fixed electrode is on the concave curved surface of the glass metallized layer and is made. Overload when the diaphragm of the protection of the concave without breaking up. Than single capacitive differential capacitance pressure thermocouple sensor of high sensitivity, good linearity, but processing more difficult ( Especially difficult to ensure the symmetry) The gas or liquid to be measured, and can not achieve in isolation, so is unfavorable to the work in corrosive fluid or impurities.
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