Directional Zone Select Interlock method and apparatus

The present invention provides a protection method and direction of the area selection means. In the present invention, the plurality of electronic trip units (the ETU) as a master device in one direction to achieve protection method selection area. ETU as a master device current direction through the respective circuit breaker when a fault occurs and the point of fault is determined based on the relationship between the current direction may be collected by a communication bus (110), and then determine the position of the respective open circuit fault point determined an operation delay time, the delay time of the instruction and issues respective ETU.