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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Plug-In Connectors (Connectorized®)
Please contact Application Engineer for firmware related to your hardware platform. The current revision does not apply to all hardware.
The Firmware IDs for older versions of the firmware can typically be found in Appendix A of the instruction manual.