Industrial 0551003X531X Overcurrent Relay Reclosing Relay

SEL-551 Overcurrent/Reclosing Relay, part number 0551003X531X, is a microprocessor-based protection and control device for electric power distribution that detects overcurrent conditions and provides automatic reclosing of the associated circuit. It can be powered from either 48–125 VDC or 125 VAC, enabling flexible integration with common substation and switchgear power architectures. The unit accepts a 5 A phase and 5 A neutral secondary input, aligning with typical CT outputs used in protection schemes, and is designed for horizontal panel-mount installation in switchgear or control cabinets. Communications are via RS-232 with front and rear ports for configuration and monitoring, supporting straightforward setup and remote diagnostics. This model is part of the SEL-551 family, a widely used protection and reclosing solution in utilities and industrial facilities for coordinating fault isolation with rapid service restoration on feeders and buses.