ASD-411 digital motor protection and monitoring device suitable for 3kV to 10kV small current grounding system of high-voltage motors, to spacer layer device, complete protection, monitoring and control, communications, and other functions. Main functions: a) definite time overcurrent protection and negative-sequence current protection; b) stall protection; c) start-up time is too long protection; d) inverse-time overcurrent protection and inverse time negative sequence current protection; e) overheating protection; f) protection of low-voltage and voltage phase sequence protection; g) the overload alarm; h) PT disconnection and CT of small current grounding line selection function; i) zero-sequence current protection function; j) break monitoring function. k) event logging, fault recording