Description
The GE Multilin 760-P5-G5-S5-HI-A20-R-B is a specialized, micro-processor based feeder management protective relay belonging to the GE Multilin SR (System Receiver) series. It provides comprehensive primary and backup protection, control, and metering for utility and industrial distribution feeders, featuring an integrated 4-shot programmable autorecloser loop.
The extensive alphanumeric part number dictates the exact hardware block profile, voltage tolerances, and I/O board configurations pre-installed inside this specific draw-out chassis unit.
📋 Comprehensive Part Number Breakdown
The specific option parameters selected for this module break down as follows:
| Code Segment | Parameter Category | Functional Specification |
|---|---|---|
| 760 | Base Model Series | Feeder Management Relay with Advanced Protection & Autorecloser |
| P5 | Phase Current Inputs | 5 A Phase Current Transformer (CT) secondary inputs |
| G5 | Ground Current Inputs | 5 A Ground/Zero-Sequence Current Transformer inputs |
| S5 | Sensitive Ground Input | 5 A High-sensitivity ground fault monitoring current input |
| HI | Control Power Supply | High-Voltage Range: 88 to 300 V DC or 70 to 265 V AC @ 48–62 Hz |
| A20 | Analog Array Interface | Eight active 4–20 mA analog output channels |
| R | Breaker Status Indication | Faceplate LED configured as Red for “Breaker Closed” status |
| B | Front Panel Interface | Basic display configuration (Standard vacuum fluorescent/LCD screen variant) |
⚡ Technical Specifications
| Parameter | Value / Specification |
|---|---|
| Brand / Manufacturer | General Electric (GE Grid Solutions / Multilin) |
| Current Input Burden | <0.02 Ω typical per phase at rated 5 A inputs |
| Frequency Tracking Range | Nominal 50/60 Hz system tracing (16 to 65 Hz execution bounds) |
| Relay Contact Ratings | Make/Carry 30 A for 0.2 s; Continuous 10 A resistive loop capability |
| Analog Accuracy | ±0.5% of full scale for 4–20 mA outputs |
| Chassis Profile | SR-series specialized full-drawout case design |
| Ingress Sealing Class | IP40 (Front bezel mounted installation footprint) |
| Operating Temperature | −40 to +60 ∘C (Standard factory ambient screening limits) |
🛠️ Engineering Considerations and Field Deployment Notes
Redundant CT Phase Saturation Avoidance
Because this specific relay framework is fitted with standard 5 A phase inputs (P5/G5), verify that the upstream measurement current transformers (CTs) installed inside the switchgear bay have matching 5 A secondary outputs. Ensure that the CT class (e.g., 10P20 or C400) provides sufficient performance under worst-case symmetrical short-circuit conditions. If high-current saturation occurs, the secondary current waveform will distort, causing delayed inverse time overcurrent (51P/51G) trip times or unwanted directional element calculation errors.
“HI” Supply Transient Immunity
The HI universal power board is highly robust, easily bridging standard station battery configurations (110 V DC or 220 V DC) and standard alternating plant grids (120/230 V AC). To shield the internal power conditioning layer from high-frequency inductive switching noise across the supply rail, always run the supply lines through a dedicated external terminal fuse point, keeping power and communication cable bundles physically separated within the panel trunking.
Draw-out Frame Mechanical Interlocks
The SR draw-out chassis design allows engineers to hot-extract the target inner relay assembly for secondary calibration testing without dismantling the backend terminal panel wires. The chassis housing features built-in mechanical automatic shorting bars on all CT input circuits.
Critical Safety Rule: Prior to sliding the relay block out of its housing case, always visually double-check through the chassis alignment slot that the internal CT shorting contacts have properly closed. A faulty mechanical interlock that leaves an active CT secondary circuit open will generate extreme high-voltage spikes, causing immediate arc-flash destruction of the terminal block and terminal breakdown.
💬 Frequently Asked Questions
What does the sensitive ground input (S5) add to this relay profile?
The S5 input provides an isolated, high-resolution current channel designed to capture very low leakage currents (down to fractions of an Ampere). This setup is critical for identifying high-impedance ground faults—such as a downed line resting on dry concrete—which do not generate enough fault current to trip standard 5 A phase or ground monitoring loops.
Can the basic display (B option) show full wave oscillography plots?
No. The B character code represents the basic alphanumeric textual monitoring screen dashboard. While the internal processing core captures detailed event logs and COMTRADE waveform files during trip events, retrieving these oscillography records requires connecting a PC to the front RS232 port or rear Modbus port using GE EnerVista setup software.
How do I modify the analog output scale parameters mapped to the A20 card?
The eight 4–20 mA output loops are fully programmable via the software dashboard. You can assign any measured parameter (such as Phase A Current, Active Power Megawatts, or Power Factor) to any of the eight physical outputs, customizing the min/max value scaling to accurately match the telemetry tracking bounds required by your plant DCS or SCADA RTU.
Technical Notice: Check your active protection relay settings files, setpoint parameters, and firmware compatibility benchmarks using the GE Multilin EnerVista suite
