I/O modules

Product Overview

This feeder management relay delivers comprehensive protection for medium-voltage distribution networks. It integrates overcurrent, ground fault, and voltage protection into a single compact housing. The SR750 750-P5-G5-D5-HI-A20-R-E monitors feeder circuits and executes trip commands during abnormal conditions. Engineers can configure this relay through either the front-panel interface or remote communication links. Its multifunctional design eliminates the need for multiple discrete protection devices.

Technical Specifications

The SR750 750-P5-G5-D5-HI-A20-R-E measures 22.0 cm in height, 18.5 cm in width, and 15.0 cm in depth. This unit weighs approximately 4.2 kg, including all internal components and mounting brackets. It operates on a control voltage of 125 VDC or 120 VAC with a maximum consumption of 45 W. The relay provides five current inputs and four voltage inputs for complete feeder monitoring. Its non-volatile memory stores up to 64 event records with accurate time-stamped data. An analog output of 20 mA allows process variable retransmission to external devices. The front panel features a backlit LCD screen for real-time measurements and fault display.

Protection Functions and Logic

This relay includes 50/51 phase overcurrent protection with selectable inverse-time curves. It offers 50N/51N neutral ground fault protection alongside 67 directional overcurrent elements. The SR750 750-P5-G5-D5-HI-A20-R-E provides undervoltage (27) and overvoltage (59) protection with adjustable thresholds. It also supports frequency protection (81) and breaker failure protection functions. Programmable logic enables users to create custom protection schemes for specific applications. The unit includes reclosing functionality with multiple shot configurations.

Communication and I/O Capabilities

This relay supports multiple protocols for seamless integration with SCADA systems. It features a rear RS485 port for Modbus RTU and DNP 3.0 serial communication. The also includes an Ethernet port for IEC 61850 and Modbus TCP/IP connectivity. A front-panel USB port provides convenient access for local configuration and firmware updates. The unit delivers eight contact outputs and accepts eight digital inputs for external signaling.

Physical and Electrical Parameters

Installation and Setup Procedures

Mount the on a standard 35 mm DIN rail inside your control panel. Maintain adequate clearance around the unit for proper heat dissipation. Connect current inputs using appropriate CT wiring practices and voltage inputs via VT connections. The relay powers up automatically after you apply the control voltage. Configure protection parameters through the front-panel keypad or the software interface. The unit performs continuous self-diagnostics to monitor hardware and software integrity.

Typical Applications

This feeder relay serves utility substations, industrial plants, and commercial power distribution systems. It protects transformers, switchgear, and motor control centers from overcurrent faults. The SR750 750-P5-G5-D5-HI-A20-R-E also performs load shedding and automatic transfer switching duties. Its comprehensive protection suite fits radial and loop network topologies equally well.

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