Capacitor is a complicated thing because it is composed of many basic elements. 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 caused by manufacturing process. Take High-voltage capacitors for instance: The capacitor is usually composed of multiple components in parallel circuit, each component is made of aluminum foil as an electrode, and a solid medium is placed between the electrodes, they are winded together. The plate area of the component is large. Due to the malfunction in raw materials and manufacturing processes, impurities, mechanical damage, pinholes, and low cleanliness may be present in the medium, which become inherent hidden dangers of capacitors. In the system, there are potential effects of overvoltage, overcurrent and surrounding high and low temperatures caused by various reasons, these weak points will then cause dielectric breakdown. Sparks are usually generated during breakdown, which further expands the range, thereby forming a multi-layer short circuit or even a short circuit of the entire components.

The voltage on the elements in series circuit will increase accordingly, and the element groups connected in parallel circuit will be shorted, causing the voltage across the remaining series to rise, and the current through each component will follow. It will lead to rapid aging of each component and increase heat generation. At the same time, partial discharge at 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, the other components of the entire series with the faulty component will break down one after another, and a new series group will be short-circuited. The number of series groups will be further reduced, the component voltage will be further increased, and the overcurrent phenomenon will be more serious. The medium deteriorates further, the temperature rises further, the arc will further increase, and the impregnating agent will further release gas. If this continues, more and more components will be damaged, and the expansion of the box shell will become more and more serious.

In this case, the fuse and relay protection should be removed in time. If not, further breakdown will form a strong arc in the box shell, and other parallel capacitors and system energy will be very short.

In this case, the protective fuse and relay protection should cut off the faulty capacitor in time. If it cannot be cut off, further breakdown will form a strong arc in the box shell, and the influx of other parallel capacitors and system energy will occur in a short time.

During the time, the capacitor medium is rapidly aging and swelling, and finally the case will inflate. In severe cases, an explosion will occur. This kind of accident cannot be eliminated by the user. The root cause of it is the early damage of the capacitor, and the cycle is usually about one year. Only manufacturers try to improve product quality and strengthen detection methods in order to reduce the early damage rate. Therefore, when selecting compensation capacitors, qualified units should try their best to choose collective and self-healing capacitors with reliable performance.

The solution relies on the manufacturers, they should 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.