ASB-4101 digital auxiliary transformer protection and monitoring device suitable for transformer protection, complete protection, monitoring and control functions to the factory. Main functions: a) three-stage composite voltage start overcurrent protection; b) zero-sequence voltage blocking two sections of high-pressure side of the zero-sequence overcurrent and high-pressure side of the zero-sequence current blocking zero sequence overvoltage protection; c) the low pressure side of the zero-sequence segment overcurrent protection; d) Overload protection; e) low-voltage protection function; f) body protection: heavy gas action, over-temperature trip, light gas alarm and over-temperature alarm; g) PT disconnection and insulation monitoring ; h) event logging, fault recorder.