Electricity measurement method of measuring the electrical amount must first will be measured the electrical signal into electrical signal, and then input. Design according to the characteristics of the different non electrical quantity into the relevant conversion device called a transducer, and measured the mechanical quantity into capacitance change such as displacement force speed sensor called capacitance sensor.

From the perspective of energy transformation in terms of capacitive transducer for passive converter, needs to be measured after the mechanical quantity into a voltage or current amplification and processing line displacement and angular displacement of the mechanics, spacing, distance, thickness, tensile, compression, expansion and deformation and so on all has close ties with the length of the quantity, the volume and is measured by length or the length ratio of the amount, the relationship and its measuring method are very close. In addition, in some conditions, these dynamics to change slowly, and is a very small range. If required when measuring very small distance or displacement to have higher resolution and other sensors is accomplished very hard to achieve high resolution requirements. Widely used in precision measurement of differential transformer sensor resolution only reach 1-5 micron order of magnitude, and there is a kind of capacitance micrometer, he 0.01 microns, the resolution of the two orders of magnitude higher than that of the former, the maximum range of 100 microns, so his favor in the small precision displacement measurement. To these dynamics, especially slow change or small quantity measurement, generally USES the capacitive sensor for testing is good, mainly is this kind of sensor has the following advantages:

1, large measuring range Its relative changes can exceed 100%;

2, high sensitivity, If use ratio transformer bridge, relative variation can be up to 10-7 orders of magnitude;

3, fast dynamic response Natural frequency because of the small movable quality high frequency characteristic is suitable for dynamic measurement, can also be static measurement;

4, good stability Because the capacitor plate of metal materials plate lining of inorganic materials, such as air, glass, ceramics, quartz, etc.; So you can in the high temperature, low temperature, strong magnetic field, strong radiation under long-term work, especially under high temperature and high pressure environment detection problem.