Differential protection device and protection system for monitoring objects to be protected in a power supply network

A differential protection device for monitoring a first object to be protected in an electrical energy supply network, the differential protection device comprising:

• a measuring unit configured to acquire measurement values at one end of the first object to be protected, the measurement values indicating a current flowing at the one end;
• a communication unit configured to exchange measurement values with a second differential protection device disposed at another end of the first object to be protected, wherein said communication unit having a physical interface for transmitting and receiving the measurement values;
• an evaluation unit configured to form a differential value with mutually assigned measurement values from both ends of the first object to be protected and to generate a fault signal indicating a fault with regard to the first object to be protected if the differential value exceeds a predefined threshold value;
• the differential protection device being configured to monitor at least one further object to be protected at a same time as the first object to be protected and to exchange respective further measurement values with regard to each further object to be protected, wherein all the measurement values are transmitted and received via a same physical interface;
• and
• the differential protection device being further configured to automatically recognize other differential protection devices connected to it via a communication connection and to assign a respective associated differential protection device to each monitored object to be protected.