Description
| Product model | SR750-P5-G5-S5-HI-A20-R-T |
| Manufacturer | GE Vernova (formerly GE Grid Solutions / Alstom Grid) |
| Product category | Digital Busbar Protection Relay |
| Core function | High-speed differential protection for single or double busbar systems |
| Current inputs | 1 A or 5 A nominal; HI version with high-input impedance (≥100 kΩ) for reduced CT burden |
| Number of bays | Up to 24 bays (configurable), supports complex bus configurations |
| Output relays | G5 configuration: Enhanced output package with 16 SPDT output contacts |
| Communication interfaces | Dual Ethernet (IEC 61850-9-2LE, GOOSE, MMS), RS-485 (Modbus RTU/ASCII), USB, IRIG-B input, RS-232 serial port |
| Power supply | 18–72 VDC, 24–48 VDC, or 110–130 VDC; optimized for DC control systems (P5 variant) |
| Frequency range | 45–65 Hz, auto-sensing for 50/60 Hz systems |
| Environmental operating range | -30°C to +70°C (-22°F to 158°F), 5–95% RH (non-condensing) |
| Installation method | Panel-mounted (19” rack or switchgear cubicle), S5 case size (452 mm width) |
| Hardware revision | R-T: Indicates a specific hardware revision with enhanced thermal management and component layout |
Product introduction
The SR750-P5-G5-S5-HI-A20-R-T GE is an advanced digital busbar protection relay designed for maximum flexibility and reliability in demanding substation environments. As part of GE’s SR750 Series, this model is specifically tailored for applications requiring extensive I/O, robust DC power handling, and superior communication capabilities. The SR750-P5-G5-S5-HI-A20-R-T delivers ultra-fast, secure, and selective differential protection for single and double busbar configurations, ensuring minimal fault clearing times and enhanced system stability.
This variant features the P5 power supply option, designed to operate efficiently on low-voltage DC control systems (18–72 VDC), making it ideal for battery-backed installations in power plants, industrial facilities, and renewable energy sites. The G5 output configuration provides 16 SPDT relay contacts—double the standard G1 package—enabling direct control of multiple breakers, alarms, and auxiliary systems without external relay augmentation. Housed in the larger S5 enclosure (452 mm width), the SR750-P5-G5-S5-HI-A20-R-T offers ample space for internal components and improved heat dissipation, enhancing long-term reliability.
The HI (High-Impedance Input) design minimizes CT burden, preserving accuracy over long cable runs, while the R-T hardware revision includes improved thermal design and component layout for enhanced durability in high-temperature environments. With dual Ethernet ports supporting IEC 61850 GOOSE and MMS, as well as an RS-232 port for legacy system integration, the SR750-P5-G5-S5-HI-A20-R-T is a future-proof solution for both new digital substations and retrofits of older infrastructure.
SR750-P5-G5-S5-HI-A20-R-T GE
Core advantages and technical highlights
Enhanced I/O and power supply flexibility:
The SR750-P5-G5-S5-HI-A20-R-T GE stands out with its G5 output package, offering 16 SPDT contacts for comprehensive trip, alarm, and status signaling—critical in complex bus schemes with multiple breakers and interlocks. The P5 power supply variant supports a wide range of DC voltages (18–72 VDC), ensuring compatibility with diverse station battery systems and eliminating the need for external power converters.
High-impedance inputs for long-distance CT applications:
The HI configuration provides input impedance ≥100 kΩ, drastically reducing the load on current transformers. This is essential in large substations or retrofits where CT secondary cables span hundreds of meters, preventing signal degradation and ensuring accurate differential measurements even under high fault currents.
Robust communication and system integration:
Equipped with dual Ethernet ports for IEC 61850-9-2LE and GOOSE, the SR750-P5-G5-S5-HI-A20-R-T enables high-speed peer-to-peer communication with other IEDs, reducing reliance on central SCADA systems for critical protection functions. The inclusion of an RS-232 port allows direct connection to local HMI devices or legacy control systems, bridging the gap between modern and older infrastructure.
Superior physical design and reliability:
The S5 case size (452 mm) provides greater internal volume for improved airflow and component spacing, reducing thermal stress. The R-T hardware revision incorporates enhanced PCB layout and thermal management, increasing mean time between failures (MTBF) and ensuring stable operation in harsh environments with temperature extremes and high EMI.
Scalable and secure protection logic:
Supporting up to 24 bays, the SR750-P5-G5-S5-HI-A20-R-T can protect complex topologies including double bus, breaker-and-a-half, and ring bus systems. Its advanced differential algorithm includes adaptive restraint, harmonic blocking, and automatic topology detection, ensuring high security during external faults and CT saturation while maintaining sensitivity to internal faults.
Typical application scenarios
The SR750-P5-G5-S5-HI-A20-R-T GE is ideally suited for large utility substations with complex bus arrangements requiring extensive relay outputs and robust DC power handling. In a 230 kV breaker-and-a-half substation, the G5 output package allows direct tripping of multiple breakers per bay, while the P5 power supply ensures uninterrupted operation during AC power loss, relying solely on the station battery.
In industrial power systems such as oil refineries or data centers, the SR750-P5-G5-S5-HI-A20-R-T protects main distribution buses where high availability is critical. Its HI inputs are essential when switchgear is located far from the control room, and the RS-232 port enables integration with local control panels for on-site monitoring and diagnostics.
Renewable energy installations, including offshore wind farms and large solar parks, benefit from the SR750-P5-G5-S5-HI-A20-R-T’s reliability and communication flexibility. The S5 case and R-T hardware revision ensure stable performance in high-temperature or corrosive environments, while dual Ethernet ports support redundant IEC 61850 networks for maximum data availability.
Railway traction substations also deploy this model due to its compatibility with 24–48 VDC control systems and ability to handle complex bus configurations. Whether protecting a single bus with multiple feeders or a double bus with bus couplers, the SR750-P5-G5-S5-HI-A20-R-T delivers the performance and scalability needed for mission-critical applications.
SR750-P5-G5-S5-HI-A20-R-T GE
Related model recommendations
SR750-P1-G1-S1-HI-A20-G: Compact version with universal AC/DC power supply and 8 outputs, ideal for smaller installations.
SR745-W2-P1-G1-HI-E-H: Feeder protection relay that complements the SR750-P5-G5-S5-HI-A20-R-T in comprehensive substation schemes.
SR469-P5-HI-A20-H: Generator protection relay with matching P5 power supply for power plant integration.
L90 Line Differential Relay: Used for transmission line protection, often coordinated with the SR750-P5-G5-S5-HI-A20-R-T.
SR751: Motor protection relay for large motors, frequently installed in the same switchgear lineup.
GE Multilin S60: Integrated protection and control platform that can host SR750 functionality in a system-level solution.
UR Series Configuration Tool: Essential software for configuring, commissioning, and monitoring the SR750-P5-G5-S5-HI-A20-R-T.
GE ION Enterprise: SCADA and power management system for aggregating data from multiple SR750-P5-G5-S5-HI-A20-R-T units.
Installation, commissioning and maintenance instructions
Installation preparation:
Before installing the SR750-P5-G5-S5-HI-A20-R-T GE, ensure the panel is de-energized and locked out. Verify the panel cutout (452 mm width for S5 case) and mounting depth. Use shielded, twisted-pair cables for CT, VT, and communication wiring. For HI inputs, confirm CT secondary ratings and avoid paralleling unless designed. Connect the P5 power supply within the 18–72 VDC range and ensure proper grounding. After mounting, use UR Setup software via Ethernet or USB to verify firmware, configure settings (bay assignments, differential thresholds), and test communication links.
Maintenance suggestions:
Perform annual functional tests using a secondary injection set to validate differential operation and all 16 output contacts. Review event records and oscillography data quarterly. Keep firmware updated via secure USB or Ethernet. Inspect terminal blocks and internal connections every 18 months, especially in high-vibration environments. Verify IRIG-B time sync monthly. The SR750-P5-G5-S5-HI-A20-R-T requires no routine calibration but benefits from periodic communication loopback tests to ensure GOOSE and Modbus integrity.
