Main characteristic parameters of thermal power ve

2022-08-07
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The main characteristic parameters of the capacitor

refer to the toughness testing equipment 1. The nominal capacitance and allowable deviation

the nominal capacitance is the capacitance marked on the capacitor. The deviation between the actual capacitance and the nominal capacitance of the capacitor is called error, and the accuracy is called within the allowable deviation range. The corresponding relationship between accuracy grade and allowable error: 00 (01) - ± 1%, 0 (02) - ± 2%, I - ± 5%, II - ± 10%, III - ± 20%, IV - (+20%-10%), V - (+50%-20%), VI - (+50%-30%) general capacitors commonly use grade I, II and III, electrolytic capacitors use grade IV, V and VI, which are selected according to the purpose

2. Rated voltage

the maximum DC voltage effective value that can be continuously added to the capacitor under the minimum ambient temperature and rated ambient temperature is generally directly marked on the capacitor shell. If the working voltage exceeds the withstand voltage of the capacitor, the capacitor will break down and cause irreparable permanent damage

3. Insulation resistance

DC voltage is applied to the capacitor and generates leakage current. The ratio of the two is called insulation resistance When the capacitance is small, it mainly depends on the surface state of the capacitance. When the capacitance is> 0.1uF, it mainly depends on the performance of the medium. The smaller the insulation resistance, the better. Time constant of capacitance: time constant is introduced to properly evaluate the insulation of large capacity capacitance, which is equal to the product of insulation resistance and capacity of capacitance

4. Loss

under the action of electric field, the energy consumed by the capacitor due to heating in unit time is called loss. All kinds of capacitors have specified the allowable loss within a certain frequency range. The loss of capacitors is mainly caused by dielectric loss, conductivity loss and the resistance of all metal parts of the capacitor. Under the action of DC electric field, the loss of capacitor exists in the form of leakage conductivity loss, which is generally small. Under the action of AC electric field, the loss of capacitor is not only related to leakage conductivity, but also related to the establishment of periodic polarization. It is not easy to choose plastic materials for experiments. They use two different transverse stripe ranges

5, 264.8 frequency characteristics

with the increase of frequency, the capacitance of general capacitors decreases. (end)

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