Area selection means for protection directional interlocking

The present invention provides such a circuit breaker (CB) to achieve directional selection zone interlock (DZSI) protection device (EDP). The external protective device can select a region in a conventional breaker interlock (the ZSI) function. The apparatus comprises a protective circuit breaker can be connected to an input interface (IE) and an output interface (OE), and a forward interface relay connected to another transmitting circuit breaker interlock signal (IF / OF) and trans the interface (IB / OB). The protective device in the control unit (the CTRL), configured to determine a current flowing through the circuit breaker (CB) in the direction of the current coincides with a predetermined reference current direction, if yes, to enable the forward interface (IF / oF), or enabling the reverse interface (IB / OB).