Capacitor is a complicated thing, because it is composed of many basic components. Due to raw materials and manufacturing processes, many capacitors produced by small factories are prone to impurities, mechanical damage, pinholes, and low cleanliness.
Early damage to the capacitor is mostly due to manufacturing reasons. High-voltage capacitors: usually composed of a plurality of components, each of which is made of aluminum foil as an electrode, and a solid medium is placed between the electrodes. The plate area of the component is large. Due to raw materials and manufacturing processes, impurities, mechanical damage, pinholes, and low cleanliness may be present in the medium, which is an inherent hidden danger of the capacitor. 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 component in series with the breakdown component will increase, and the component group connected in parallel will be shorted, causing the voltage across the remaining series to rise, and the current through each component will follow. Increasing will result in rapid aging of the various components, increasing the amount of heat generated. At the same time, partial discharge of the edge of the plate will also occur under the action of higher voltage. In addition, the discharge of the breakdown point will cause the impregnating agent to release a large amount of gas. After a certain period of time, the other components of the entire series in series with the faulty component will be successively broken down, and a new series group will be shorted. Further reduction, the component voltage is further increased, the overcurrent phenomenon is more serious, the medium is further deteriorated, the temperature is further increased, the arc is further increased, the impregnating agent will further release the gas, and thus, the component damage is more and more, and the casing is expanded. getting more serious. In this case, the fuse and relay protection should be removed in time, if not removed. Further breakdown will form a strong arc in the casing, and other parallel capacitors and system energy will be very short. During the time, the capacitor medium is rapidly aging and expanding, and finally the casing expands. In severe cases, an explosion may occur. This kind of accident cannot be eliminated by the user. It belongs to the early damage of the capacitor, and the cycle is usually about one year. Only manufacturers try to improve product quality and strengthen testing methods in order to reduce the early damage rate. Therefore, when selecting the compensation capacitor, the conditional unit should try to select a reliable, self-healing capacitor with reliable performance.