Description
Product Introduction & Engineering Value
When an unexpected thermal trip locks out a critical 4.16 kV boiler feed pump motor, standard overload relays give you zero context on why it happened. Facilities relying on the GE Multilin 369-HI get full visibility into motor health rather than blind shutoffs.
The “HI” specification designates GE’s wide-range control power supply (50–300 VDC or 60–265 VAC), allowing seamless drop-in integration across diverse plant auxiliary power buses. Operating with real-time thermal capacity monitoring and customizable FlexCurve protection, this module replaces multiple discrete panel devices—reducing wiring clutter while preventing catastrophic stator and rotor failures.
Technical Specifications
| Parameter | Specification |
| Control Power Supply (HI) | 50 to 300 VDC / 60 to 265 VAC (45–66 Hz) |
| Phase Current Inputs | 1 A or 5 A Secondary (Field Selectable) |
| Ground CT Inputs | 50:0.025 A, 1 A, or 5 A |
| Frequency Tracking Range | 20 Hz to 100 Hz (VFD Compatible) |
| Thermal Protection | 15 Standard Overload Curves + Custom FlexCurve |
| Digital Inputs / Outputs | 6 Optically Isolated Inputs / 4 Form-C Output Relays |
| Serial Communication | 1 x Front RS232 Port, 3 x Rear RS485 Ports (Modbus RTU) |
| Display Panel | 40-Character Backlit LCD with LED Motor Status Indicators |
| Enclosure Rating | NEMA 12 / IP54 Front Panel |
| Operating Temperature | -20°C to +60°C (-4°F to 140°F) |
Field Application & The “Trench” Experience
A mining operation in northern Minnesota suffered repeated nuisance tripping on an overland conveyor motor during sub-zero morning startups. The existing analog thermal overload relays were miscalculating motor heating due to extreme ambient swings. The maintenance team retrofitted the panel with a GE Multilin 369-HI relay. By pulling live data from RTDs and leveraging the thermal memory feature, the 369-HI correctly tracked true stator heating while bypassing cold-weather transient surges, preventing daily startup delays and saving hundreds of lost production hours.
Specific Field Applications
- Submersible “Down-Hole” Well Pumps: Prevents dry-running using undercurrent detection and manages backspin time-delay logic before restart.
- Refinery Induced-Draft Fans: Tracks acceleration times and limits starts-per-hour to protect large high-inertia rotor bars from thermal cracking.
- Ball Mill Drive Motors: Monitors current unbalance and rapid mechanical jam/stalling on heavy industrial crushing circuits.
- 369-HI
- 369-HI
Transparency SOP: QA & Testing
- Power Supply Stress Test: High-voltage bench verification operating the internal “HI” power supply card at 50 VDC, 250 VDC, and 240 VAC to confirm DC-DC converter stability.
- Current Injection Testing: Secondary current injection across all phase and ground CT terminals to calibrate trip time accuracy against standard IEEE/ANSI curves.
- Optically Isolated I/O Validation: Testing discrete switch inputs and triggering all output relays under load to check contact resistance.
- Communication Port Sweep: Automated ping and setpoint download verification across the front RS232 port and all rear RS485 channels using EnerVista setup software.
- Burn-in & Thermal Cycle: 12-hour active monitoring in an environmental chamber to catch potential component thermal drift.
The Veteran’s Tech Trap Guide
⚠️ CT Secondary Shorting Hazards: Before disconnecting current input wiring from the rear of a 369-HI, always ensure external CT shorting blocks are securely closed. Opening a live CT circuit will generate lethal high-voltage arcs across the terminal block.
PRO TIP: When replacing an older 369 relay, never rely on memory alone to transfer settings. Export the complete .369 setpoint file via EnerVista setup software from the old unit and verify that the firmware revision on the replacement card matches before writing the file.
⚠️ DIP Switch & Ground Selection: Pay close attention to the ground CT input rating jumpers. Connecting a 50:0.025 zero-sequence CT to a terminal configured for a 5A secondary will result in complete failure of ground fault protection.
Dynamic FAQ
Q: What does the “HI” suffix mean on a GE Multilin 369 relay?
A: “HI” indicates the high-range control power supply option (50–300 VDC or 60–265 VAC). If your station auxiliary power is 24 VDC or 48 VDC, you require the “LO” power supply model instead.
Q: Can the 369-HI relay be used on motors driven by Variable Frequency Drives (VFDs)?
A: Yes. The 369-HI features frequency tracking from 20 Hz to 100 Hz, making it suitable for monitoring PWM inverter-fed motors without false trips caused by harmonic distortion.
Q: How do I upgrade option features (like RTD inputs or Metering) on an existing 369-HI relay?
A: Many hardware options (such as the “R” RTD module or “M” metering package) are factory-built options, but certain firmware features can be unlocked via software passcodes supplied directly by GE Multilin.
Q: Does the 369-HI include warranty coverage upon purchase?
A: Yes, all New Surplus and fully reconditioned GE Multilin 369-HI units include a standard 1-year functional replacement warranty backed by complete bench-test documentation.
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