GE SR469-P5-HI-A20 – Integrated Thermal Modeling & Differential Protection for Critical Motors

Description

Application Scenarios

At a large LNG compression facility in the Gulf Coast, a critical 6.6 kV, 5.000 HP compressor motor suffered repeated insulation failures due to undetected high-impedance ground faults in the resistance-grounded system. Traditional overcurrent relays failed to respond because fault currents remained below pickup thresholds. After installing the GE SR469-P5-HI-A20. the plant leveraged its dedicated HI (High-Impedance) ground fault element, which detected subtle ground leakage as low as 0.1 A through sensitive residual current sensing. Within weeks, the relay identified an incipient stator winding fault during routine operation, triggering a controlled shutdown before catastrophic failure occurred. The early warning saved over $ 2 million in motor replacement and avoided a 72-hour production outage.

This case exemplifies how the SR469-P5-HI-A20 transforms motor protection from reactive tripping to proactive asset health management—turning electrical data into actionable intelligence.

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Technical Principles and Innovative Values

Innovation Point 1: High-Impedance (HI) Ground Fault Detection

Unlike standard ground fault elements that rely on zero-sequence CTs and trip at >1–5 A, the HI feature in the SR469-P5-HI-A20 uses advanced signal processing to detect sub-ampere ground leakage—critical in high-resistance grounded (HRG) systems where fault currents are intentionally limited. This enables early detection of insulation degradation before it escalates into phase-to-phase faults.

Innovation Point 2: Advanced Thermal Modeling

The relay employs a dual thermal model—one for rotor (during start/stall) and one for stator (during running)—that dynamically adapts to load conditions. It accounts for copper losses, ambient temperature (via RTDs), and cooling effects during stops, providing far more accurate thermal capacity tracking than simple I²t curves.

Innovation Point 3: Integrated Asset Health Monitoring

With 8 RTD inputs, the relay continuously monitors motor bearing and winding temperatures. Combined with event logs, waveform captures, and operational counters (starts, run hours), it enables condition-based maintenance—alerting operators to abnormal heating trends long before failure.

Innovation Point 4: Cyber-Secure Communication & Control

The built-in Ethernet port supports Modbus TCP with configurable IP settings, allowing seamless integration into SCADA and IIoT platforms. Optional password protection and secure firmware updates ensure compliance with NERC CIP and IEC 62443 guidelines for critical infrastructure.

Application Cases and Industry Value

Case Study: Mine Hoist Motor Protection (South Africa)

A deep-level gold mine replaced aging electromechanical relays with GE SR469-P5-HI-A20 units on its 4.16 kV hoist motors. The relays’ start inhibit function prevented dangerous restarts during cage positioning, while jam protection detected a seized gearbox within 200 ms—avoiding shaft shear. Over 18 months, unplanned hoist downtime dropped by 65%, directly improving ore extraction rates.

Case Study: Municipal Water Pump Station (California)

A city upgraded its flood-control pump station with SR469-P5-HI-A20 relays featuring Ethernet connectivity. Operators now monitor motor health remotely via a cloud dashboard, receiving SMS alerts for thermal overloads or bearing overheating. During a heatwave, the system flagged a pump motor running 15°C above baseline—leading to scheduled bearing replacement before failure, preventing urban flooding risk.

Related Product Combination Solutions

To build a complete motor protection and control system, the GE SR469-P5-HI-A20 is often paired with:

GE C60 or D60: For feeder or busbar protection coordination

GE UR Series IEDs: For integrated substation automation

Zero-Sequence CTs (e.g., GE ZSCT): For enhanced ground fault sensitivity

RTD Sensor Assemblies: PT100/PT1000 probes embedded in motor windings/bearings

GE Enervista UR Setup Software: For configuration, testing, and event analysis

Redundant Power Supplies: To ensure relay operation during control voltage loss

Installation, Maintenance, and Full-Cycle Support

Proper installation of the SR469-P5-HI-A20 requires correct CT polarity, secure grounding of the relay chassis, and shielding of analog and communication cables to prevent EMI. The HI ground fault element must be calibrated based on system capacitance and grounding resistor value—typically performed during commissioning using injection testing.

Maintenance is largely predictive: review event reports, thermal utilization logs, and RTD trends quarterly via Enervista software. Firmware should be kept up to date to benefit from security and performance enhancements. The relay’s self-test diagnostics verify internal health at power-up and during operation.

As a certified supplier of legacy and current GE Multilin products, we provide factory-new or reconditioned SR469-P5-HI-A20 units, each tested for all protection functions—including HI ground fault response—and communication integrity. Every unit includes a 24-month warranty, configuration backup, and technical support for integration into existing protection schemes.

Protect your most critical rotating assets with precision. Contact us for genuine GE SR469-P5-HI-A20 relays—tested, supported, and ready to deploy.