Current differential relay and current differential relay system using current differential relay thereof

A current differential relay employed in a current differential relay system that protects transmission lines linking installations by a plurality of current differential relays, said current differential relay comprising:

• an interface section that receives current supplied from said transmission line;
• a quantization section that quantizes a received current and converts said received current to first current data;
• a communication section that, in a case where a relay is a representative current differential relay of a first group formed of some current differential relays in said plurality of current differential relays, receives second current data from another current differential relay belonging to said first group, transmits said second current data and said first current data jointly to a representative current differential relay belonging to said second group, receives third current data from said representative current differential relay, and transmits said third current data to said other current differential relay;
• a difference calculation section that executes a current difference calculation based on said first to third current data;
• and
• a control section that controls said interface section, said quantization section, said communication section and said difference calculation section.

A current differential relay system that protects transmission lines linking installations by a plurality of current differential relays,

• wherein a current differential relay comprises:
• an interface section that receives current supplied from said transmission line;
• a quantization section that quantizes said received current and converts said received current to first current data;
• a communication section that, in a case where a relay is a representative current differential relay of a first group formed of some current differential relays in said plurality of current differential relays, receives second current data from another current differential relay belonging to said first group, transmits said second current data and said first current data jointly to a representative current differential relay belonging to a second group, receives third current data from said representative current differential relay, and transmits said third current data to said other current differential relay;
• and
• a difference calculation section that executes a current difference calculation based on said first to third current data.