RXE300 series microcomputer protection device is a new generation of microcomputer-type integrated protection device launched by the company, which combines the characteristics of power system relay protection with the latest microcontroller development technology. Adopting single-chip solution, the digital part is composed of highly integrated 32-bit industrial-grade microcontroller, which makes the device powerful, strong anti-interference performance, and very convenient for calibration and query. This terminal has the functions of fault indicator, DTU, relay protection, voltage-time type controller, voltage-current type controller, demarcation load switch controller, watchdog controller and so on. It can not only realize local isolation and self-healing of faults, but also upload the three remotes and fault information to the main station of distribution network dispatching, and realize isolation and self-healing of faults through the centralized mode of the main station or set up a fault location system.