HVCAPACITOR
Por que a capacidade dos capacitores de alta tensão decai após um período de tempo de trabalho?

First of all, for example, the N4700 ceramic we use, the temperature drift is about 20%, and it is negative temperature, that is to say, the lower the temperature, the larger the capacity, on the contrary, the higher the temperature rise, the smaller the capacity. In the high frequency and high voltage environment, the capacity of the capacitor will be attenuated, which is a normal phenomenon. Almost all materials have attenuation, and materials with a large dielectric constant such as N4700 will be more obvious. Compared with microwave ceramics, NP0 ceramics, this phenomenon is very prominent.

Secondly, capacitors made of ceramic materials have bias characteristics. The higher the voltage and the higher the frequency, the greater the attenuation of the capacity. Not only ceramic capacitors, but also film capacitors. After high temperature and high pressure capacitors, the capacity will change, except for a few NP0 or microwave ceramics. This phenomenon is more pronounced in high dielectric constant ceramics. In materials with a dielectric constant within 180, especially in materials with a dielectric constant within 100, there is almost no problem. This is because ceramic capacitors with small dielectric constants such as NP0 materials have very small dielectric loss and very good temperature characteristics, with almost no temperature drift, so the attenuation is very small after high frequency, high pressure and high temperature. The usual N4700 material has a dielectric constant between 1000 and 3500, so the attenuation of this large dielectric material is obvious.

If you want to choose a capacitor with minimal attenuation, you can only choose ceramic materials with small temperature drift and low dielectric loss. If you can’t accept the capacity after attenuation, you can slightly increase the nominal capacity when customizing the ceramic capacitor. For example, for the usual 1400PF capacitor, the actual capacity of Japan TDK is 1600PF, which is to compensate for the capacity deviation caused by attenuation.

Capacity decay is a normal phenomenon, as long as it is a capacitor, this problem exists. In order to avoid risks, choose materials carefully. The attenuation of ceramic capacitors is relatively small. If ceramic materials with small dielectrics can be selected, the attenuation of capacitance will be significantly improved.