Film capacitor safety

We all know that film capacitors have good performance, high demand, and self-healing properties. They are used in all walks of life. So, do you know where the safety of film capacitors comes from? Let's talk about the safety of film capacitors.

The film capacitor is selected from a certain proportion of oil wax or sulfur hexafluoride as the impregnating agent, and the impregnating agent is poured into the capacitor shell by vacuum impregnation, which can effectively eliminate the partial discharge phenomenon at the edge of the core, and the crystallite after curing The wax forms a stress zone outside the core. When the component self-healing, due to the existence of certain stress, it can quickly extinguish the arc, preventing the evaporation zone from expanding and self-healing and causing component accidents. Compared with the liquid impregnating agent, the oil wax impregnating agent has stable performance, does not burn, and effectively solves the oil leakage problem.

In the event that the film capacitor fails due to self-healing, the internal metallized film is softened by heat and deflated to cause the capacitor to expand, and the safety device can cut off the power supply in time to protect the entire device. There are many types of safety devices, such as mechanical and electrical types. The fuse of the film capacitor is integrated with electric fuse and has a dual function. It is placed inside the capacitor case, and the fuse is used to start the safety device and cut off the power supply. In case the mechanical insurance is out of control, the electric insurance starts immediately. The power is also turned off to protect the entire device.

When the film capacitor is out of operation, the self-discharge device can reduce the initial peak voltage of the capacitor when it exits operation to less than 50V within 3 minutes to ensure safe operation and maintenance.