DIGITAL PROTECTION RELAY

PROBLEM TO BE SOLVED: To highly precisely set a setting value of a digital protection relay. SOLUTION: In the digital protection relay 3, a calculation part 34 performs relay functions, when system electrical quantity, inputted from a power system 2 having a protection object 1 via electrical quantity reduction means CT1, CT2 and the like, is larger than the set value by a prescribed quantity. The system electrical quantity at stationary times, which the calculation part 34 fetches, are stored to a memory 35 as the set value. Thus, the set value is set. When the system electrical quantity, input after the setting value is set, is larger than the set value which has been set in the memory 35 by a prescribed quantity, the calculation part 34 executes relay functions. COPYRIGHT: (C)2007,JPO&INPIT