Year1
- 电压：
- 10V
- 容量：
- 2.2UF
- 封装尺寸：
- 1.6*0.8
Tooohm (
Ohm
Giohm (
Ohm
Megohm
(
Ohm
In addition to materials and dimensions, There are other physical factors that will affect the insulation resistance of the capacitor.
Surface resistivity Since the surface absorbs impurities and moisture, the surface resistivity of the medium is inconsistent with the volume resistivity. Contact Ouyang to request a free sample
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The defective medium is composed of polycrystalline ceramic polymers, and the grain boundaries and pores present in its microstructure will always reduce the intrinsic resistivity of the material. From a statistical point of view, the probability of occurrence of these physical defects is directly proportional to the component volume and structural complexity. Therefore, for components with larger size, larger electrode area, and more electrode layers, the resistivity and dielectric strength are lower than that of small-sized components.
.Capacitor dielectric loss
In an AC circuit, the phase difference between the voltage and current on an ideal capacitor is, and the relationship is expressed by the following formula
For AC bias Voltage,
Here. is the amplitude of the sinusoidal signal, "is the frequency.
Because
And the electric current
Because ( + &)
Therefore the current phase It must be ahead of the voltage phase. However, the actual medium is not an ideal device, the material resistivity cannot be infinite, and the delay effect or relaxation time of the polarization mechanism with frequency will always produce losses.
The above model is for an ideal capacitor Generally speaking, it must be corrected in actual use. The actual capacitor model can be regarded as a parallel structure of an ideal capacitor and an ideal resistor.
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At this time, the AC voltage on the capacitor is the current of the ideal capacitor & for the ideal resistor, so the total current is The phase difference with the voltage is not. The phase difference angle between the actual current and the ideal current is certain, and the tangent value of this angle is defined as the loss tangent or loss factor, as shown in the figure below.
Actual capacitor current< br/> Electricity
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Voltage
Loss angle tangent in actual capacitors Contact Ouyang for free sample sending and free request
The loss tangent is an intrinsic characteristic of the material and does not depend on the geometric size of the capacitor. The loss tangent has a great influence on the application of dielectric materials in the electronic field. In actual use, it is often found that the dielectric constant is lower The material loss factor is also lower. High-quality materials with strong polarization mechanisms also have higher loss factors.
. Frequency effect of dielectric loss
As mentioned above, the frequency range used by dielectric materials has a significant impact on Its polarization mechanism has a significant impact, mainly on the polarization relaxation process or time delay of the material with the reversal of the AC electric field. The relaxation time of the instantaneous polarization process is short, and the relaxation time of the delayed polarization process is long. Among the atoms and ions that make up ceramic media, the latter causes greater dielectric losses. The loss value occurs when the frequency of the external electric field is synchronized with the time period of the relaxation process. In short,
When the relaxation time is very different from the external electric field period, the loss is very small
Relaxation time & electric field frequency, the loss is small
Relaxation time & electric field frequency, the loss Small
Relaxation time electric field frequency, loss
Under the conditions, the polarization response speed is much smaller than the speed of external electric field reversal, and the ions cannot keep up with the changes in the electric field at all, so no heat loss occurs. On the contrary, the polarization process can easily keep up with the electric field frequency, without delay or loss. However, under certain conditions, although ions can keep up with changes in the electric field, they are limited by the relaxation time, resulting in losses.
The relaxation times of ceramic media made of polycrystals are always outside the spectral range. The change of dielectric loss and dielectric constant with frequency is consistent, and both are related to the polarization mechanism, as shown in the figure below. In high-frequency applications, a quality factor called a factor is often used, which is equal to the reciprocal of the loss tangent
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