Arc-Fault Circuit Interrupter (AFCI) is an emerging requirement in solar system and also gradually becomes the mandatory requirement in some countries or areas according to the laws and regulations. Based on UL 1699B, AFCI is required to employ for solar equipment to prevent dangers, especially fires occurring in PV panel installations. Arc current detection is needed to collect and analyze the AC noise current present on the DC current between the PV string and inverter, then distinguish an arc and non-arc event.

Arc current can range from a dozen mA to several Amperes, and the frequency spectrum can be low to several KHz and up to several hundreds of KHz. The frequency requires the current sensor has high sensitivity, high bandwidth, and low noise level. Current transformer (CT) can provide high measurement accuracy and safety isolation between the primary high current side and the secondary low current side. This has been widely used as arc current detection sensor. While the disadvantages of CT are, the CT has burden power loss and occupies large PCB size. In-package hall-effect current sensing design is also becoming one of the new trends in arc current detection.