The SEL-551 Overcurrent/Reclosing Relay replaces the many relays, control switches, and wiring required in traditional distribution substation protection and control panels. The relay also replaces line recloser control packages at a fraction of the cost.SEL-551/SEL-551C and SEL-851 Comparison
Asset Protection—Monitor and protect distribution feeders, distribution buses, transformers, capacitors, or circuit breakers.
Current Transformer (CT) Connection Versatility—Connect the separate neutral-current input to accommodate core-balance CTs, separate neutral CTs, tertiary-winding CTs, or CT ground-residual circuits.
Reclosing Control—Coordinate with downstream reclosers using sequence coordination logic to program up to four reclosing attempts.
Field-Proven Ruggedness—Program SELogic control equation inputs and outputs to meet application needs in multiple environments. A wide operating temperature range (–40° to +85°C) allows installation in a control house or outdoor enclosure.
Comprehensive Overcurrent Protection
The SEL-551 provides phase, negative-sequence, residual ground, and neutral overcurrent protection in a compact package, including a complete set of instantaneous, definite-time, and time-overcurrent elements.
acSELerator QuickSet SEL-5030 Software
QuickSet helps speed up the relay application by allowing you to develop relay settings offline, program SELogic control equations, and analyze post-fault event reports.
Protection and Control Logic
SELogic control equations with SELogic variables and timers allow traditional or advanced protection schemes. Programmable local control elements permit front-panel pushbutton control. Programmable text display points provide enhanced local operator information.
Monitoring and Reporting
The SEL-551 features Instantaneous, peak, and demand metering. The latest twenty 15-cycle oscillographic data event reports and the latest 512 Sequential Events Recorder (SER) records are stored in nonvolatile memory.
The front-panel EIA-232 serial port, the rear-panel EIA-232/EIA-485 serial port, and the ASCII, binary, and Modbus RTU protocols enhance integration capabilities.
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The Firmware IDs for older versions of the firmware can typically be found in Appendix A of the instruction manual.