Reactive Power Compensation - AC Input Type

Due to the fact that capacitors are devices that cannot experience voltage transients, they will generate large inrush currents when they are put into operation, and the maximum inrush current may exceed 100 times the rated current of the capacitor. Surge can cause adverse interference to the power grid and reduce the service life of capacitors. In order to reduce inrush current, most compensation devices use capacitor switching special contactors, which have a set of auxiliary contacts connected in series with current limiting resistors in parallel with the main contacts. During the process of contactor closing, the auxiliary contacts are first connected, allowing the capacitor to be connected to the circuit through the current limiting resistor for pre charging, and then the main contacts are connected to connect the capacitor to the circuit normally. In this way, the inrush current can be limited to less than 20 times the rated current of the capacitor.
This type of compensation device is inexpensive, highly reliable, and widely used. Due to the limited contact life of AC contactors, they are not suitable for frequent switching, so this type of compensation device is not suitable for frequently changing load conditions.