GE Multilin SR750-P5-G5-S5-HI-A20-R-T Feeder Protection Relay

GE Multilin SR750-P5-G5-S5-HI-A20-R-T SR750 Feeder Protection Relay

Configured for comprehensive protection, monitoring, and control in utility and industrial power distribution systems, the GE Multilin SR750-P5-G5-S5-HI-A20-R-T (SR750 Feeder Protection Relay) provides direct physical/electrical execution. The unit accepts 5 A Phase CT, 5 A Ground CT, and 5 A Sensitive Ground CT inputs to drive ANSI 50/51, 50N/51N, 50G/51G, breaker failure, and thermal overload algorithms. Operating across an AC/DC universal power supply range of 88-300 VDC or 70-265 VAC, the relay processes virtual inputs and programmable logic while streaming event records, waveform captures, and diagnostics via Modbus RTU/TCP, DNP3.0, or IEC 60870-5-103 protocols.

Suffix Breakdown & Model Matrix

• SR750: Base Series designation for the Multilin SR750 Feeder Protection System.
• P5: Phase CT Secondary rating configured for 5 A inputs.
• G5: Ground CT Secondary rating configured for 5 A inputs.
• S5: Sensitive Ground CT Secondary rating configured for 5 A inputs.
• HI: Universal High-Power Supply range rated for 88-300 VDC and 70-265 VAC.
• A20: Hardware revision and options package incorporating 4-20 mA analog outputs and enhanced hardware options.
• R: Rear-mount terminal connections for panel cutout installation.
• T: Enhanced Ethernet communication and transient recording feature code.

Hardware Specifications

Backplane Bus Communication Velocity and Firmware Flash Compatibility

The GE Multilin SR750-P5-G5-S5-HI-A20-R-T manages internal backplane bus communication velocity during high-density trip execution sequences. Internal microprocessors preserve firmware flash compatibility while processing real-time current vectors, virtual logic state changes, and automated breaker interlocks. By maintaining deterministic network isolation between local protective elements and external Ethernet SCADA polling, the hardware prevents processing latencies during fault-triggered waveform capture and event logging.

Frequently Asked Questions

Q: How does the SR750-P5-G5-S5-HI-A20-R-T handle primary current transformer sizing for ground fault detection?

A: The module includes dedicated 5 A inputs for Phase CT (P5), Ground CT (G5), and Sensitive Ground CT (S5) channels, allowing independent scaling for standard overcurrent and high-sensitivity ground fault detection.

Q: What power source range is compatible with the "HI" power supply option?

A: The "HI" universal power supply operates seamlessly on either DC auxiliary power from 88 VDC to 300 VDC or AC auxiliary power from 70 VAC to 265 VAC.

Q: How does the hardware maintain real-time telemetry during local network outages?

A: The relay writes timestamped event records and high-speed waveform data directly to non-volatile internal memory, allowing full diagnostic retrieval over Modbus or DNP3.0 once network connection resumes.

Field Installation Guidelines

Field engineers and wiring technicians must adhere to the following installation rules during cabinet mounting:

• Insert the 220 mm x 180 mm x 200 mm case into the standard panel cutout, securing the rear chassis mounting brackets to maintain mechanical stability.
• Connect the auxiliary power conductors to the HI terminals, verifying supply voltage falls within the 88-300 VDC or 70-265 VAC operating range.
• Route Phase, Ground, and Sensitive Ground CT 5 A secondary wiring through dedicated shorting terminal blocks before terminating on the relay rear panel.
• Connect a heavy-gauge copper grounding wire from the panel frame ground directly to the relay ground lug to satisfy IEC 61000 EMC immunity standards.
• Lay Ethernet communication cables in separate wireways isolated from 5 A current input circuits to mitigate electromagnetic interference.