Characteristics Of Capacity Sensor
November 24,2021
Wholesale Capacity Sensor Supplier Factory
When it comes to capacity sensors, many people will feel strange and have never heard of them. In fact, capacity sensors are widely used in the measurement of displacement, angle, vibration, velocity, pressure, component analysis, dielectric characteristics and so on. Today we will introduce the advantages and disadvantages of capacity sensors.
Advantages
✅Good temperature stability.
The capacitance value of the capacity sensor is usually independent of the electrode material, which is conducive to the selection of materials with low-temperature system, and has little impact on the stability because it produces little heat. The resistance sensor has resistance and generates heat after power on: the inductance sensor has copper loss, magnetic flux and eddy current loss. Due to the heat, it is easy to produce zero drift.
✅Simple structure.
Capacity sensors are simple in structure, easy to manufacture, easy to ensure high accuracy, and can be made very small to achieve some special measurements: they can work in harsh environments such as high temperature, strong vehicles and ships and strong magnetic field, and can withstand large temperature changes, high pressure, high impact overload, etc. It can measure ultra-high temperature and low pressure difference, as well as magnetic work.
✅Good dynamic response.
Because the electrostatic attraction between the plates with electrodes is very small (about 105N), the energy required by the capacity sensor is very small, and because its moving part can be made very small and thin, that is, its weight is very light. The natural frequency is very high, the dynamic response time is short, and it can work at the frequency of several megahertz, which is especially suitable for dynamic measurement. And because of its low dielectric loss, it can supply power through a higher frequency, so the system has a higher working frequency. It can be used to measure rapidly changing parameters.
✅Non contact measurement that can achieve average effect.
For example, non-contact measurement of vibration or eccentricity of rotating shaft, radial clearance of small ball bearing, etc. When using non-contact measurement, capacity sensor has the function of average value, which can reduce the influence of working surface roughness on measurement. In addition to the above advantages, the capacity sensor also has small electrostatic attraction between the electrode plates, so the input energy are very small. Therefore, it can measure extremely low pressure, small acceleration, displacement, etc. it can be made into a very sensitive, high-resolution sensor: due to its low dielectric loss (such as air), when the differential structure is connected into a bridge, the zero residue is very small, so the circuit is allowed to be amplified at a high power, so that the instrument has high sensitivity.
Disadvantages
❎High output impedance, poor load capacity.
The capacity of capacity sensor is limited by general geometric dimensions, usually only a few PF to hundreds of PF, which makes the output impedance of the sensor very high. Therefore, the load capacity of the sensor is very poor, and vulnerable to external interference and instability. In severe cases, it doesn't even work. Shielding measures must be taken, which brings great inconvenience to design and use. Large impedance also requires that the resistance value of the insulating part of the sensor is very high (more than dozens of MQ), otherwise the insulating part will be used as bypass resistance and affect the performance of the instrument (such as reducing sensitivity). Therefore, special attention should be paid to the surrounding environment such as temperature and cleanliness. Not using high-frequency power supply will reduce the output impedance of the sensor, but high-frequency amplification and transmission are much more complex than low-frequency, and parasitic capacitance has a great impact, which is not easy to ensure the stability of work.
❎Due to the limitation of structure and size, the capacitance of type sensor is very small.
The lead capacitance connects the sensor and electronic circuit (the lead of 1-2m can reach 800pF). The volume capacitance of other electronic circuits and the "parasitic capacitance" formed by the inner plate of the sensor and its surrounding conductors are relatively large, which not only reduces the sensitivity of the sensor. Moreover, these capacitors (cable capacitance) often change randomly, which will make the instrument work very unstable. It affects the measurement accuracy, so there are requirements for cable selection, installation and connection. With the development of materials, technology, electronic technology, especially integration technology, the advantages of capacity sensor are carried forward, but the disadvantages are overcome. Capacity sensor is gradually becoming a kind of sensor with high sensitivity and high precision, and is expected to be developed in dynamic, low voltage and some special measurement fields.
If you want to wholesale capacity sensor, Ningbo Technic Lighting is a good choice, we can provide you with high quality products, plz feel free to contact us.
Wholesale Capacity Sensor Supplier Factory
?Tel: 86-574-62795970 ?Email: www.technic-lighting.com
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