Patent ID: 6906903
Filing Date: 2005-06-14
Classification: H02H

Abstract:
1. A protection relay for determining whether or not a fault point of a power system exists in a predetermined range, comprising: filter means for inputting sampling data of a voltage and a current in the power system to a digital filter having a predetermined transfer function and outputting first voltage data and first current data, and second voltage data and second current data normal to the first voltage data and the first current data, respectively; calculation means for calculating a predetermined measurement value based on the first voltage data, the first current data, the second voltage data and the second current data at a first time and the first voltage data, the first current data, the second voltage data and the second current data at a second time different from the first time; and operation decision means for performing an operation decision based on the predetermined measurement value obtained by the calculation means, wherein the filter means comprises: