GE Multilin SR750-P1-G1-S1-HI-A20-R-E-H – Feeder Protection Relay for MV/LV Switchgear

The GE Multilin SR750 is a proven feeder management relay designed to protect medium- and low-voltage feeders with dependable overcurrent and earth-fault protection, metering, event records, and flexible I/O. This configured variant (SR750-P1-G1-S1-HI-A20-R-E-H) seems to be built for utility and industrial switchgear where you want straightforward protection, familiar Multilin logic, and simple integration to existing SCADA. From my experience, users pick SR750 because it’s stable in tough panels and easy for technicians to service.

Company’s Order Placement Process and Guarantees

• Warranty period: 365 days
• Delivery time: typically 1 week if in stock; no more than one month at the latest
• Payment: 50% advance payment; full payment prior to delivery
• Express delivery: FedEx, UPS, DHL

Key Features

• Feeder protection (50/51, 50N/51N, thermal): Time-overcurrent, instantaneous, and ground-fault elements cover the common trip scenarios on MV/LV feeders.
• Directional ground and negative-sequence options: In many cases, directional logic helps discriminate faults on complex networks and tie feeders.
• Four current channels (3ϕ + ground): Supports 1 A/5 A CTs, typically selectable, which simplifies retrofit jobs.
• Flexible I/O: Discrete inputs for breaker status and permissives; Form C outputs for trip/alarms and lockout schemes.
• Metering and records: Feeder currents, demand values, event/fault records, and time stamping for post-fault analysis.
• Communications for SCADA: RS485 (Modbus RTU) and, when the build includes it, Ethernet for Modbus TCP—handy for central monitoring.
• Draw-out serviceability: You might notice the chassis is designed for quick replacement, which cuts outage time during maintenance.
• Harsh panel readiness: The SR series typically tolerates electrical noise and heat in crowded MCCs better than many newer “IT-style” devices.

Technical Specifications

Note: Values below reflect typical SR750 family data; specific option codes can alter I/O and ports. If you need us to verify against your serial/build sheet, we’ll check before shipment.

Application Fields

This model fits feeder protection in metal-clad switchgear, MCC incomers, and plant distribution boards. Typical deployments:

• Industrial plants (cement, steel, pulp & paper): incomer and tie feeders, process substations
• Oil & gas and chemicals: unit substations, utility tie lines, export feeders
• Mining: conveyor feeders, pump stations, and underground distribution
• Utilities and campuses: ring-main units, distribution feeders, and capacitor bank feeders

One thing I appreciate is how the SR750 behaves on retrofit projects—many legacy GE panels already have the cutout and wiring conventions, so the changeover tends to be faster than a full relay platform swap.

Advantages & Value

• Reliability: The SR series has a long track record; nuisance trips are rare when CT ratios and pickup settings are reviewed carefully.
• Compatibility: Modbus RTU/TCP keeps SCADA integration simple; no need for proprietary gateways in most cases.
• Lifecycle cost: Spare parts and trained personnel are widely available, which typically reduces long-term maintenance risk.
• Technical support: Settings templates for common feeder schemes speed up commissioning and reduce on-site time.

A maintenance supervisor told me they swapped an older electro-mechanical scheme with an SR750 in a day, and the event records alone paid for the effort after the first feeder fault.

Installation & Maintenance

• Panel & environment: Install in a clean, ventilated switchgear or MCC compartment; keep ambient within -20…+60°C. Provide adequate clearance for the draw-out case and rear cabling.
• Power & grounding: Use a stable auxiliary supply within the stated range. Bond relay ground to the control ground bar; avoid ground loops.
• CT/VT wiring: Verify CT ratios and polarity (H1 orientation); short CT secondaries during work; use shielded twisted pairs for analog signals where practical.
• Digital I/O: Match input voltage type to the relay’s rating; interpose relays for high-burden coils; label all trip and alarm circuits.
• Communications: For RS485, terminate the last device (120 Ω) and keep A/B polarity consistent; for Ethernet builds, segregate the protection VLAN and disable unused services.
• Routine care: Back up settings after any change, review disturbance records after faults, and clean front panel/keypad during scheduled outages. Firmware updates are done cautiously and usually off-line, after a settings backup.
• Commissioning tip: Start with conservative pickup and time dial settings, validate trips in a controlled test, then fine-tune to coordination curves.

Quality & Certifications

• Standards: Typically tested to IEC/IEEE protection relay standards (IEC 60255 series)
• Certifications: CE compliant; UL/CSA recognition is common for SR7xx units
• RoHS/REACH: Dependent on manufacturing revision; we can verify against your unit’s serial number
• Warranty: 365-day warranty from us; manufacturer’s original warranty may vary by build year and condition