Sequence based network protector relay with forward overcurrent protection and antipumping feature

A network protector relay for controlling a circuit breaker connected between a polyphase feeder bus and a polyphase network bus, said network protector relay comprising:

• digital sensing means digitally sampling polyphase current flowing through said circuit breaker and polyphase network voltage on said network bus at least sixteen times per cycle to generate digital polyphase current samples and digital polyphase network voltage samples;
• digital processor means comprising means for generating positive sequence current and voltage vectors from said digital polyphase current samples and digital polyphase network voltage samples, and means tripping said circuit breaker open in response to a selected relationship between said positive sequence current and voltage vectors indicating flow of current from said polyphase network bus to said polyphase feeder bus above a predetermined threshold;
• wherein said digital sensing means digitally samples said polyphase current and said polyphase network voltage sequentially and wherein said digital processor means includes means adjusting phase angles of said digital polyphase current samples and digital polyphase network voltage samples for such sequential sampling;
• and
• wherein said digital processor means includes means deriving from said digital polyphase current samples and said digital polyphase voltage samples metered parameters, and wherein said digital sensing means digitally samples said polyphase current and said polyphase network voltage alternately in a first order for a given number of cycles and then in a second order which is a reverse of the first order for said given number of cycles.