Description
Product Core Brief
- Model: GE Multilin SR469-P5-HI-A20-E
- Brand: GE Multilin (General Electric)
- Series: 469 Motor Management Relay Series
- Core Function: Comprehensive protection, monitoring, and control for medium/high-voltage motors
- Product Type: Digital Protective Relay
- Key Specs: 5 A Phase CT Secondaries HI (88-300 Vdc/70-265 Vac) Supply Enhanced Display
GE SR469-P5-HI-A20-E
Key Technical Specifications
- Phase Current Inputs: 5 A Secondary (for use with 5 A CTs)
- Ground Current Input: 5 A or 1 A (Selectable)
- Control Power (HI): 88–300 Vdc or 70–265 Vac (Universal High-voltage range)
- Analog Outputs (A20): 4 programmable 4–20 mA outputs
- Display Option (E): Enhanced display with backlit LCD
- Protection Elements: 26 (Overload), 46 (Unbalance), 50/51 (Overcurrent), 87M (Differential)
- Communication Ports: 1 x Front RS-232, 2 x Rear RS-485 (Modbus RTU)
- Input/Output: 6 Assignable Output Relays, 5 Digital Inputs
- Dimensions: Standard 469 horizontal rack-mount chassis
- Monitoring: Current, Voltage, Power (W, var, VA), Energy, Temperature (12 RTD inputs)
GE SR469-P5-HI-A20-E
Application Scenarios & Pain Points
The SR469 is the “gold standard” for protecting large induction and synchronous motors in critical industrial processes. When you are dealing with a 5,000 HP motor driving a main cooling pump or a massive compressor, the relay isn’t just a fuse—it’s a data logger and a diagnostic tool. The most painful scenario for a plant is a “Nuissance Trip” during a startup, or worse, a failure to trip during a rotor stall.
The SR469-P5-HI-A20-E specifically solves the problem of high-reliability environments where universal control power is required. However, these units are often targeted by “chip-level” repair shops that sell poorly refurbished boards. In my experience, using a refurbished relay on a multi-million dollar motor is a gamble you don’t want to take. Our New Surplus units ensure the internal electrolytic capacitors and sensing transformers are at factory-spec.
Typical Application Scenarios:
- Oil & Gas – Centrifugal Compressors Using the Thermal Model and RTD feedback to prevent winding insulation breakdown in high-ambient environments.
- Mining – Large Ball Mills & Crushers Providing mechanical jam and broken rotor bar protection to prevent catastrophic mechanical failure.
- Water Treatment – High-Lift Pumps Managing complex starts and monitoring power quality to protect against voltage dips and unbalance.
- Power Generation – ID/FD Fans Utilizing differential protection (87M) to detect internal winding faults before they cause a fire.
Case Study: The “Mystery Trip” in an Air Separation Plant
Background: A large industrial gas plant was losing their main nitrogen compressor motor every time a heavy load hit the local grid. Their old relay was a basic thermal-only unit.
The Problem: The motor was tripping on “Thermal Overload,” but the RTDs showed the windings were cool. The old relay couldn’t account for the current unbalance caused by the grid fluctuation.
The Solution: We supplied an SR469-P5-HI-A20-E. The engineer used the 469’s sophisticated thermal model, which integrates both RTD temperature and current unbalance (negative sequence current) into a single thermal image.
Result:
- Outcome: By accurately calculating the heating effect of the unbalance, the 469 prevented the nuisance trips while still protecting the motor.
- Cost Savings: The plant avoided three restarts per week, saving an estimated $12,000 in energy and lost production per event.
- Engineer’s Insight: The A20 (4-20 mA) outputs were used to feed the motor’s actual thermal capacity into the plant DCS for real-time load shedding.
Compatible Replacement Models
The 469 series has a specific ordering code. If one letter is off, the relay might not fit your CTs or your control voltage.
| Original Model | Replacement/Alternative | Compatibility | Key Differences | Change Required |
| SR469-P5-HI-A20-E | SR469-P1-HI-A20-E | ❌ Incompatible | P1 is for 1 A CTs. Using this on 5 A CTs will burn the relay. | Must change all CTs to 1 A. |
| SR469-P5-HI-A20-E | SR469-P5-LO-A20-E | ❌ Incompatible | LO power is for 24-48 Vdc only. | Will blow if connected to 220V control power. |
| SR469-P5-HI-A20-E | 869-P5-HI-A20-E | ⚠️ Software Compatible | The 869 is the modern “Multilin 8” successor. | Requires a different mounting cutout and software. |
Troubleshooting Quick Reference
| Symptom | Possible Cause | Related to SR469? | Quick Check | Action |
| “In Service” LED Off | Internal Self-Test Fail | ✅ High | Check the “Status” menu via front panel/RS-232. | If “RAM Error” or “Unit Not Ready,” replace relay. |
| “Ground Fault” Trip | CT Polarity or Leakage | ⚠️ Medium | Verify the H0 CT wiring and “Phase-CT” direction. | Check cable insulation if wiring is correct. |
| LCD is Blank (Unit Alive) | Backlight Failure | ✅ High | Shine a flashlight at the LCD to see if characters are visible. | Replace the front display/HMI assembly. |
| Comm Error (RS-485) | Termination/ID Conflict | ⚠️ Medium | Check the Modbus Address and 120 Ohm resistor. | Ensure no two relays share the same ID. |
| “RTD Sensor Open” | Wiring or Sensor Break | ❌ Low | Measure resistance at the relay terminals (should be ~100-120 Ohms). | Repair the wiring to the motor windings. |
❗ Pro-Tip: The “HI” Voltage Warning
The “HI” control power module is robust, but it’s susceptible to high-voltage transients in DC battery systems. If you are replacing a unit that “died” during a substation switching event, I strongly recommend adding a surge suppressor to the A1/A2 power terminals. It costs 50 and can save a 5,000 relay.
