Patent ID: 7231003
Filing Date: 2007-06-12
Classification: H02H,H04B

Abstract:
1. A first relay for performing current differential protection of a protected apparatus, the current differential protection utilizing a first and a second communication channel transmitting data between a second relay and the first relay, the first and second relays operating on respective portions of a power line of an electrical power system, the first relay comprising: a local sample circuit configured to generate a local stream in response to receipt of an electrical current signal from a local power line portion; a first processing circuit operatively coupled to the local sample circuit and the first communication channel, the first processing circuit configured to align, filter and compare the local stream and a first remote stream from the second relay to generate a first logic value, and to determine a first channel status based on the first remote stream; a second processing circuit operatively coupled to the local sample circuit and the second communication channel, the second processing circuit configured to align, filter and compare the local stream and a second remote stream from the second relay to generate a second logic value, and to determine a second channel status based on the second remote stream; and a selection logic circuit operatively coupled to the first and second processing circuits, the selection logic circuit configured to determine a control signal based on the first channel status and the second channel status, the control signal applied to an output contact of the first relay.