Adaptive BOWL impedance relay

An adaptive BOWL impedance relay is proposed in this paper. Compared with the circular and quadrilateral impedance relays, it has the advantages of larger coverage of fault resistance, simple criterion, fast operation, mature technique, easy setting, good phase selection, distinct directionality, accurate distance measurment, high security in heavy load and easy to realize adaption. Simulating calculation and practical tests have verified the analyses. The BOWL relay has been applied in microprocessor-based distance protection developed by our institute