Smart open motor protector ARD2 Series (hereinafter referred to as Protector) utilizes advanced single chip technology and is featured in the strong anti-interference, stable and reliable running, digitalization, intelligence and networking. The protector can protect the motor from timeout startup, overload, phase failure, unbalance, under-load, earth leakage, blocking, short circuit, external fault and other abnormalities during the running and provide the SOE fault event recorder to help maintenance stuff find causes. It is applicable for coal mines, petrochemical industry, metallurgical industry, power industry, shipbuilding, civil building and other fields. It is equipped with the RS485 remote communication interface and the DC4-20mA analog output, which is convenient to form a network system together with control machines like PLC and PC to realize the remote monitoring of motor.