Causes of early damage to capacitors

The early damage to the capacitor is mostly due to manufacturing reasons. A high-voltage capacitor is usually composed of a plurality of components, each of which is made of an aluminum foil as an electrode, and a solid medium is placed between the electrodes and wound. The plate area of the component is large. Due to raw materials and manufacturing processes, impurities may be present in the medium and mechanical damage may occur. Pinholes, low cleanliness and other issues, this has become a hidden danger of capacitors. In the system caused by various factors such as overvoltage, overcurrent and surrounding high and low temperature, these weak points cause dielectric breakdown. Sparks are usually generated during breakdown, further expanding the range to form a multilayer short circuit or even a short circuit of the entire component.

The voltage across the components in series with the breakdown components will increase, and the component groups connected in parallel will be shorted, so that the voltage across the remaining series will increase and the current through each component will increase. . This will result in rapid aging of the individual components, increased heat generation, and partial discharge of the edge of the plates at higher voltages. In addition, the discharge at the breakdown point causes the impregnant to release a large amount of gas, and after a certain period of time, the other components of the entire series in series with the faulty element are successively broken down. In addition, a new series group is shorted, the number of series groups is further reduced, the component voltage is further increased, and the overcurrent phenomenon is more serious, the medium is further deteriorated, and the arc is further increased by further increasing the temperature. The impregnating agent will further release the gas, so that the component damage is more and more, and the casing is more and more inflated.

In this case, the fuse is relayed and the fault capacitor is cut off in time. If the breakdown is not removed, a strong arc will be formed in the case. Other parallel capacitors and system energy will quickly age and expand the capacitor medium in a short period of time, which will cause the case to expand, which may occur in severe cases. This kind of accident can't be eliminated by the user. It belongs to the early damage of the capacitor, and the cycle is usually about one year. As a manufacturer, we must pay attention to quality and strengthen the testing methods to reduce the early damage rate.