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The GE SR489-P5-HI-A20-E Generator Management Relay belongs to the GE Multilin 489 generator protection and management family. It combines generator electrical protection, metering, temperature monitoring, alarm handling and trip control in a dedicated relay package. It is used in generator control panels where electrical measurements and abnormal operating conditions must be evaluated against configured protection settings.
This configuration includes 5 A phase current transformer inputs, a high-range control power supply, 4–20 mA analog outputs and an enhanced local display. The high-range supply accepts 90–300 V DC or 70–265 V AC at 48–62 Hz. The enhanced display provides a larger LCD and improved keypad for viewing relay measurements, status and settings.
The relay processes current, voltage and connected condition-monitoring signals, then operates assigned trip or alarm outputs when configured protection criteria are met. Serial communications and analog outputs support connection to compatible supervisory equipment, allowing generator status and selected operating measurements to be incorporated into a wider plant monitoring system.
| Parameter | Specification |
|---|---|
| Manufacturer | GE |
| Model / Order Number | SR489-P5-HI-A20-E |
| Product Family | GE Multilin 489 |
| Product Type | Generator Management Relay |
| Phase CT Input Rating | 5 A |
| Control Power Option | HI |
| DC Control Power Input | 90–300 V DC |
| AC Control Power Input | 70–265 V AC |
| AC Control Power Frequency | 48–62 Hz |
| Analog Output Option | A20 |
| Analog Output Range | 4–20 mA |
| Display Option | Enhanced display with larger LCD and improved keypad |
| Digital Inputs | 9 opto-isolated inputs |
| RTD Monitoring | Supports up to 12 RTD inputs |
| Communication Interfaces | RS232 and RS485 |
| Communication Protocols | Modbus RTU, DNP 3.0 |
| Protection Functions | Configurable generator electrical and thermal protection |
| Enclosure / Mounting Format | Drawout relay package |
| Dimensions | 252 × 216 × 224 mm |
| Weight | 7.7 kg |
The SR489-P5-HI-A20-E receives generator current and voltage signals from connected instrument transformers. It processes these measurements and compares them with programmed settings for enabled protection elements, which may include overcurrent, voltage, frequency, reverse power and other generator protection functions.
RTD sensors and configured digital inputs provide additional operating information. When a measured condition satisfies a protection element’s pickup threshold and timing requirements, the relay can activate the assigned trip or alarm outputs. Event information and diagnostic data help maintenance personnel investigate abnormal operation and review the sequence of events.
The A20 option provides 4–20 mA analog outputs. Depending on the relay configuration, these outputs can represent supported measurements for compatible external meters, controllers or plant monitoring systems.
The HI option determines the auxiliary supply range required by the relay. Correct CT and VT wiring, transformer-ratio settings, protection thresholds and output assignments are essential for proper operation. The relay’s actual response depends on the functions enabled and the settings applied during commissioning.
The GE Multilin 489 serves as a dedicated generator protection and monitoring device between the generator measurement circuits, breaker-control circuitry and plant supervision system. It evaluates connected signals locally and issues configured trip or alarm commands when programmed conditions are satisfied.
| System Component | Function | Relationship to the Relay |
|---|---|---|
| Generator Current Transformers | Provide scaled generator current signals | Supply phase-current measurements matching the 5 A input configuration |
| Voltage Transformers | Provide generator voltage signals | Supply voltage measurements for configured protection and metering |
| RTD Temperature Sensors | Measure generator and bearing temperatures | Supply thermal information to configured monitoring functions |
| Generator Circuit Breaker | Connects or isolates the generator | Receives trip commands through the assigned control circuit |
| Alarm and Annunciation System | Alerts operators to abnormal conditions | Receives configured relay alarms and status information |
| Plant PLC or SCADA System | Supervises equipment and displays operating values | Exchanges supported measurements and status information |
| Engineering Computer | Configures relay settings and retrieves diagnostics | Connects through supported communication interfaces and compatible software |
| Auxiliary Control Power Supply | Powers the relay | Must meet the HI option’s specified AC or DC input range |
| Application | Protection or Monitoring Task | Role of the Relay |
|---|---|---|
| Industrial Generator Sets | Monitoring generator electrical conditions | Evaluates configured protection elements and operates assigned trip or alarm outputs |
| Standby Power Systems | Supervising generator operation during backup service | Provides generator protection and operating measurements |
| Combined Heat and Power Plants | Monitoring generators operating alongside plant loads | Consolidates protection, metering and diagnostic information |
| Industrial Power Stations | Detecting electrical and thermal operating abnormalities | Supports configured generator protection and alarm handling |
| Cogeneration Systems | Monitoring generator output and connected temperature signals | Provides electrical measurements and condition monitoring |
| Generator Control Panels | Integrating protection with breaker and operator interfaces | Connects instrument-transformer inputs, control outputs and supervisory communications |
| Component | Function | Compatibility Consideration |
|---|---|---|
| Phase Current Transformers | Supply generator phase-current signals | Match the relay’s 5 A secondary input and configured CT ratios |
| Ground Current Transformer | Supplies ground-fault current information | Select an arrangement supported by the enabled ground-protection function |
| Voltage Transformers | Supply generator voltage signals | Verify secondary ratings, connection type and programmed ratio |
| RTD Temperature Sensors | Monitor stator, bearing or other configured temperatures | Confirm sensor type and wiring compatibility |
| Generator Circuit Breaker Trip Circuit | Opens the breaker when a configured trip operates | Verify trip-coil ratings and the complete control-circuit design |
| 4–20 mA Analog Input | Receives the relay’s analog signals | Confirm input range and parameter scaling at the receiving device |
| RS485 Communication Network | Carries serial data between devices | Configure compatible communication settings and protocol |
| Plant PLC or SCADA System | Supervises generator status and measurements | Map required values using supported communication functions |
| Model | Product Type | Relationship | Selection Consideration |
|---|---|---|---|
| GE Multilin 489-P1-HI-A20-E | Generator Management Relay | Related configuration with 1 A phase CT inputs and high-range control power | Select only when the connected phase CT secondary rating requires the P1 option |
| GE Multilin 489-P5-LO-A20-E | Generator Management Relay | Related configuration with 5 A phase CT inputs and low-range control power | Compare the required auxiliary supply range |
| GE Multilin 489-P5-HI-A1-E | Generator Management Relay | Related configuration with 5 A phase CT inputs and 0–1 mA analog outputs | Consider when the receiving equipment requires the A1 output range |
| GE Multilin 489-P5-HI-A20-T | Generator Management Relay | Related configuration with 5 A phase CT inputs, high-range power and an enhanced display with Ethernet | Verify the Ethernet requirement and complete order-code configuration |
The HI option specifies the high-range control power supply. It accepts 90–300 V DC or 70–265 V AC at 48–62 Hz. The installed auxiliary supply must match these requirements.
The P5 option is for phase current transformers with 5 A secondary outputs. The connected CT ratios and phase wiring must be configured correctly in the relay settings.
A20 specifies 4–20 mA analog outputs. These can transmit supported generator measurements to compatible external monitoring and control equipment, according to the configured output assignments.
Review the event record, enabled protection elements, measured values, pickup thresholds, time delays and output assignments. Also verify CT and VT wiring and the programmed transformer ratios before changing protection settings.