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Summary of Relay Trip Circuit Design. Relay Trip Circuit Design . Special Publication of the IEEE PSRC Written by a WG of the Substation Equipment Protection Subcommittee Summary Paper in the conference Proceedings Full document available for downloading from the PSRC web site
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Relay Trip Circuit Design • Special Publication of the IEEE PSRC • Written by a WG of the Substation Equipment Protection Subcommittee • Summary Paper in the conference Proceedings • Full document available for downloading from the PSRC web site • URL is given in the Summary Paper
Purpose • Document and share information about electric utility practice in the design of • relay trip circuits • associated control and protective functions • Provide training and reference information for new relay engineers
Subject Areas • Substation Dc Systems • Relays Tripping a Single Breaker • Relays Tripping more than one Breaker • Breaker Failure Relaying Initiation • Transfer Tripping
Subject Areas, cont. • Pole Disagreement Tripping • Trip Circuit Monitoring and Supervision • Reclosing Initiation and Cancellation • Trip Circuit Apparatus • Bibliography and References • Appendix: Target Test Results
Substation DC Systems • DC systems overview • one feeder per breaker vs. tapped feeders • relay feeders • redundancy
Substation DC Systems • Trip circuit routing • radial versus loop dc • DC fault currents and coordination
Single Breaker Tripping • Direct Trip • Indirect Trip • Diodes • Auxiliary relays • Dual breaker trip coils
Multiple Breaker Tripping • Diodes versus Auxiliary Relays • Application of Diodes in Control Circuits • Application of Auxiliary Relays • Targeting with Auxiliary Relays • Trip Testing and Trip Test Switches
Breaker Failure Relay Initiation • Separation of Relay Circuits and Breaker Trip Circuits • Maintaining Breaker Failure Initiation • BFI Auxiliary Relays • Breaker Auxiliary Switches
Transfer Tripping • Transmitter Keying • Receiver Output Circuits • Direct Transfer Tripping • Permissive Overreach Transfer Tripping • 52b Switch Keying
Pole Disagreement Tripping • Independent pole tripping • Disagreement detection • Redundant dc supplies
Trip Circuit Monitoring • Trip circuit failure areas • Red light monitoring • Monitoring relays • Auxiliary relay circuit monitoring • Sneak circuits caused by monitoring
Reclose Initiation and Cancellation • Function of RI and RC signals • Means of deriving RI and RC from trips • Pulse duration considerations
Trip Circuit Apparatus • Characteristics of trip circuit devices • Auxiliary Relays • Target and Seal-in Devices • Breaker Trip Coils
Trip Circuit Apparatus, cont. • Surge protection devices • avoiding false trips caused by dc grounds and surge suppression capacitors • coil surge suppression devices
Trip Circuit Apparatus, cont. • Switches in trip circuits • purposes • pro’s and con’s • trip testing
Summary • Documents a large body of knowledge about dc trip circuit design that is not available elsewhere • Useful in explaining the reasons behind practices to new engineers and in avoiding problems discovered by others • Pertains primarily to the pre-microprocessor era, but has useful lessons for the future