Does it affect the capacitance value of the capacitive sensor?

What about capacitors? This question cannot be generalized and should be analyzed according to your specific situation. Here is a brief introduction to the use of capacitors for your reference.

1) Bypass, the bypass capacitor is an energy storage device that provides energy for the local device, which can homogenize the output of the voltage regulator and reduce the load demand. Like a small rechargeable battery, a bypass capacitor can be charged and discharged into the device. To minimize impedance, the bypass capacitor should be as close as possible to the power supply and ground pins of the load device.

This is a good way to prevent ground potential elevation and noise caused by too large input values. The ground potential is the voltage drop at the ground junction when it passes through a high-current burr. 2) Decoupling, decoupling, also known as decoupling.

In terms of circuits, it is always possible to distinguish between the source of the drive and the load being driven. If the load capacitance is relatively large, ....

In general, the factors that may be relevant to the capacitance value of a capacitive displacement sensor include the distance between the probe and the analyte, the relative area, and the change in the medium between the two. For example, dust, oil, and moisture can change the medium. Moving away from or near the object to be measured will also change the measured value.

It will also have an impact on the area. In general, for ranging capacitive sensors, if the accuracy is to be high, the change of medium and facing area must be strictly limited. Of course, factors such as temperature changes will also affect the accuracy of the sensor, and the DUT is grounded, which can shield the interference caused by the power supply, thereby improving the accuracy.

German Mi-Iridium Capacitive Displacement Transducer CAPANCDT series.

A sensor that converts measured mechanical quantities, such as displacement and pressure, into capacitance changes. The sensitive part of it is the capacitor with variable parameters. The most commonly used form is a capacitor consisting of two parallel electrodes with air as the medium between the poles (see figure).

If the edge effect is ignored, the capacitance of the plate capacitor is a δ, where is the dielectric constant of the interpolar medium, a is the effective area of the two electrodes covering each other, and δ is the distance between the two electrodes. A change in any of the three parameters, δ, a, and more, will cause a change in capacitance and can be used for measurement. Therefore, capacitive sensors can be divided into three types: pole distance change type, area change type, and medium change type.

Pole distance variation is generally used to measure small linear displacements or pole distance changes due to force, pressure, vibration, etc. (see Capacitive Pressure Sensors). The area-varying type is generally used to measure angular displacements or large linear displacements. The medium change type is often used for level measurement and the determination of temperature, density and humidity of various media.

The advantages of capacitor sensors are simple structure, low cost, high sensitivity, strong overload capacity, good dynamic response characteristics and strong adaptability to harsh conditions such as high temperature, radiation, and strong vibration. The disadvantages are that the output is nonlinear, the parasitic capacitance and distributed capacitance have a great influence on the sensitivity and measurement accuracy, and the connection circuit is more complex. Since the end of the 70s, with the development of integrated circuit technology, capacitive sensors have appeared packaged with miniature measuring instruments.

This new type of sensor can greatly reduce the influence of distributed capacitance, overcoming its inherent drawbacks. Capacitive sensors are a very versatile sensor with great potential.

In general, the relationship between the time-varying voltage v(t) and the time-varying current i(t) on an inductive element with an inductance l can be expressed by a differential equation: vt=l(dit dt).

An inductive element is an energy storage element, and the original model of the inductive element is a wire wound into a cylindrical coil. When a current i is passed through the coil, a magnetic flux is generated in the coil and energy is stored. The parameter that characterizes the ability of an inductive element (abbreviated as inductor) to generate magnetic flux and store magnetic fields, also called inductance, is denoted by L, which is numerically equal to the flux generated per unit of current.

Inductive components refer to inductors (inductance coils) and various transformers.

Precautions to be paid attention to during the use of inductors:

1. Occasions for the use of inductors: moisture and dryness, the level of ambient temperature, high-frequency or low-frequency environment, whether the inductor is inductive, or impedance characteristics, etc., should be noted.

2. Frequency characteristics of inductance: At low frequency, the inductor generally presents inductance characteristics, which only stores energy and filters high frequency. However, at high frequencies, its impedance characteristics are obvious.

There are phenomena such as energy consumption and heating, and the perceptual effect is reduced. The high-frequency characteristics of different inductors are different.

<> In overcompensation, the inductor current is greater than the capacitive current. When a single-phase grounding fault occurs, the arc suppression coil can form an inductor current that is close to the same size as the grounding current but in the opposite direction, and this current compensates with the capacitance current, so that the current at the grounding ground becomes very small or equal to zero, thus eliminating the arc at the grounding ground and all the hazards caused by it. In addition, when the arc is extinguished after the current passes through the zero value, the cautious posture of the arc suppression coil can also significantly reduce the recovery speed of the faulty phase voltage, thereby reducing the possibility of arc re-ignition.

Overcompensation is because most of the electrical load in the power system is inductive, the power factor is lag before the compensation, if the capacitor is invested to compensate for the reactive current is too much, the power factor will become advanced, which is overcompensation.

The differences between capacitors and capacitive sensors are as follows:

First, the use is different.

Capacitors are one of the electronic components widely used in electronic equipment, which are widely used in circuits such as DC blocking, coupling, bypass, filtering, tuning loop, energy conversion, control, etc. The capacitance used in the coupling circuit is called the coupling capacitor, and it is used in a large number of resistor-capacitance coupling amplifiers and other capacitive coupling circuits to play the role of blocking the DC flow and AC.

The non-electric amount that can be directly measured by the capacitive sensor is: linear displacement, angular displacement and geometric dimensions (or material level) of the medium, which can be static or dynamic, such as linear vibration and angular vibration. The converters used for the above three types of non-electrical parameter transformation measurements are generally relatively simple in principle and do not require any pre-transformation.

Second, the characteristics are different.

Capacitors have charge-discharge characteristics and the ability to block DC current from passing through, allowing AC current to pass through. During charging and discharging, there is a process of accumulation of charges on the plates, that is, there is a process of voltage build-up, so the voltage on the capacitor cannot change abruptly. The capacitive reactance of a capacitor is inversely proportional to frequency and capacitance.

That is, when analyzing the capacitive reactance, it is necessary to contact the frequency and capacity of the signal.

Capacitive sensors require low energy to operate, and capacitive sensors are particularly suitable for low input energy measurements due to the small electrostatic attraction between the plates. Due to its good dynamic characteristics, the relative change of the capacitive sensor is only limited by linearity and other practical conditions, and the capacitance can change by 100% or more when using a high linearity circuit.

Advantages: 1. The temperature is stable and the silver is well embedded;

2. Simple structure;

3. Good dynamic rolling response;

4. It can be measured by non-contact and has high sensitivity;

5. Cost-effective;

6. Strong adaptability to harsh conditions such as high temperature, radiation, and strong vibration.

Disadvantages: 1. High output impedance and poor load capacity;

2. The influence of parasitic capacitance and distributed capacitance is large;

3. The connection circuit is more complicated.

Hello dear, happy to answer for you. First, the principle of capacitive pressure sensor It uses a round metal film or a metalized film as an electrode of the capacitor, when the film feels the pressure and deforms, the capacitance formed between the film and the fixed electrode changes, and the electrical signal can be output with a certain relationship with the voltage through the measurement circuit. Capacitive pressure sensors belong to the capacitive sensors with pole distance variation, which can be divided into single capacitive pressure sensors and differential capacitive pressure sensors.

2. Common types of capacitive pressure sensorsThe common types of capacitive pressure sensors are 3051 and 1151 models, and 1151 pressure sensors have been used more in previous years. However, in recent years, 3051 pressure sensors are generally used, because 3051 pressure sensors are larger than 1151 pressure sensors and are more beautiful. Therefore, general customers choose 3051 pressure sensor, unless it is used in the past 1151 pressure sensor, and now do not choose 1151 pressure sensor.

Whether it is a 3051 pressure sensor or a 1151 pressure sensor, there are generally two forms: flat flange and insertion cylinder. What is the difference between these two forms? We all know that the temperature near the tank is lower than the liquid level temperature inside the tank, so when we need to measure the liquid level temperature inside the tank, we need to choose the pressure sensor of the insertion cylinder.

3. Capacitive pressure sensing wide retarder application examplesCapacitive pressure sensor It has a simple structure, cheap pressure, high sensitivity, high resolution, fast adaptation speed in harsh environments such as high temperature and radiation, and can solve many problems that people can not measure. Therefore, it is not only used in the measurement of some mechanical and physical quantities such as displacement, vibration, angular velocity, acceleration, etc., but also widely used in the measurement of thermal engineering parameters such as pressure, differential pressure, liquid pressure, and component content. At the same time, it is also widely used in agriculture, aerospace, petroleum research and development, Shenzi military, high-tech research and development, electron microscope adjustment, precision position measurement, etc.

Capacitive pressure sensors are used in a wide range of applications, including in industry, the automotive industry, and the aerospace industry. If you have an idea for this device, you can check out the sensor expert network.

A capacitive sensor is a kind of conversion device, which uses various types of capacitors as sensing elements to convert the measured physical or mechanical quantity into a capacitive change. In fact, it is a capacitor with variable parameters. Let's take a look at the advantages of capacitive sensors.

A capacitive sensor is a kind of conversion device, which uses various types of capacitors as sensing elements to convert the measured physical or mechanical quantity into a capacitive change. In fact, it is a capacitor with variable parameters. 1.

The capacitance value of a capacitive sensor with good temperature stability is generally independent of the electrode material, which is conducive to the selection of materials with a low temperature coefficient, and has little effect on stability due to its minimal heat generation. However, the resistance sensor has copper loss, and it is easy to cause zero drift due to heating. 2. Simple structure: Inductive sensor has simple structure, easy manufacturing, high precision, and can be made very small to achieve some special measurements.

It can work in harsh environments such as high temperature, strong radiation, and strong magnetic field, and can withstand huge temperature changes, high pressure, high impact, overload, etc. It can measure ultra-high temperature and low dropout pressure, and magnetic work can also be measured. 3.

Good dynamic response. Because the electrostatic attraction between the plates with electrodes is very small (about a few 10(-5)n), the energy of the inductive sensor is very small, and because its movable part can be made very small and thin, that is, the mass is very light, so its natural frequency is very high, the dynamic response time is short, and it can work at a frequency of several megahertz, which is especially suitable for dynamic measurement. Due to its low dielectric losses and the ability to supply power at higher frequencies, the system operates at a high frequency.

It can be used to measure parameters that vary at high speed. 4.Non-contact measurement and high sensitivity.

The vibration or eccentricity of the shaft as well as the radial clearance of the small ball bearings can be measured non-contact. In the case of non-contact measurements, capacitive sensors have an averaging effect that reduces the effect of the surface roughness of the workpiece on the measurement.