FI-3A2F is used in overhead line system. It is composed of clamp structure, body and transparent cover. The clamp structure is made of special stainless steel with low magnetic loss, and its surface processed by Zn-Ni electroplating technology improves its corrosion resistance performance. All of printed circuit boards are sealed in the upside of the fault indicator body by resin epoxy, the environment withstanding level of fault indicator will be thus improved. The fault indicator can be remotely operated by connecting the APP via communication adaptor. A 433MHz or 2.4GHz radio model integrated in the fault indicator for communication application. The high visible LED put on the side surface of the battery container ensures the long visible distance. The installation ring under the transparent cover can be easily linked to the hook of hot stick.