Description
Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | GE Multilin |
| Model | SR745-W2-P5-G5-HI |
| Product Family | Multilin 745 |
| Product Type | Transformer Protection / Management Relay |
| Transformer Configuration | W2 — two windings |
| Phase CT Input | P5 — 5 A nominal |
| Ground CT Input | G5 — 5 A nominal |
| Control Power | 90–300 VDC / 70–265 VAC |
| Frequency | 48–62 Hz |
| Protection | Differential, overcurrent, ground fault, overexcitation, frequency |
| Communication | Front RS-232; rear serial interfaces; options vary by configuration |
| Display | 40-character LCD, configuration dependent |
| Mounting | Relay case / panel mounting |
| Approx. Dimensions | 21.6 × 25.4 × 24.1 cm |
| Approx. Weight | 7.5 kg |
| Typical Application | Transformer protection and management |
The W2-P5-G5-HI option code is directly documented in SR745 setpoint files, confirming the two-winding, 5 A phase-current, 5 A ground-current and high-voltage-power configuration.
Product Introduction
The GE Multilin SR745-W2-P5-G5-HI is a transformer protection and management relay from the GE Multilin 745 series. It is designed to monitor and protect two-winding power transformers using CT and VT measurements, while providing protection logic, metering, event information, and control functions within a single relay platform. The 745 is specifically identified as a Transformer Protection System by GE Multilin references.
The GE SR745-W2-P5-G5-HI configuration uses 5 A phase-current inputs and 5 A ground-current inputs. The HI power-supply option accepts a wide auxiliary supply range of 90–300 VDC or 70–265 VAC at 48–62 Hz, making it suitable for common substation and industrial protection-panel supply systems.
The relay’s protection architecture can include transformer percentage differential protection, overcurrent protection, restricted ground-fault protection where enabled, overexcitation/volts-per-hertz protection, and frequency-related functions. The actual enabled feature set depends on the purchased configuration and relay settings; the model suffix alone should not be used to assume every optional function is installed.
SR745-W2-P5-G5-HI
The SR745-W2-P5-G5-HI is therefore an important component in transformer protection schemes where correct CT ratios, winding configuration, phase compensation, grounding arrangement, and protection settings directly affect security and dependability. A replacement relay must be configured from the original application data rather than simply powered up with factory defaults.
Main Features & Field Considerations
Transformer differential protection
The 745 platform provides transformer-specific differential protection designed to distinguish internal transformer faults from external fault conditions. CT ratio and winding configuration must be entered correctly for the protection calculation to be meaningful.
5 A CT configuration
The P5/G5 configuration is important. Both phase and ground-current inputs are associated with 5 A nominal CT secondary circuits. A 1 A CT installation should not be connected simply because the physical relay appears identical.
Wide-range control power
The HI power supply accepts 90–300 VDC or 70–265 VAC at 48–62 Hz. This should still be verified against the actual relay nameplate before energization.
Protection-engineering considerations
Before replacing an SR745-W2-P5-G5-HI, record:
- Transformer MVA rating
- Primary and secondary voltages
- CT ratios
- CT polarity
- Ground CT configuration
- Transformer vector group
- Tap range
- Differential pickup and slope settings
- Overcurrent settings
- Ground-fault settings
- V/Hz settings
- Frequency settings
- Existing FlexLogic
- Communication settings
- Firmware/software revision
Do not confuse relay with case
The is a drawout-style protection relay, and commercial references specifically note that the relay unit and case may be sold separately. When sourcing a replacement, verify whether the requirement is for the relay electronics only or the complete case assembly.
Typical Applications
The GE Multilin -W2-P5-G5-HI is used in:
- Utility transformer protection
- Industrial substations
- Power-generation plants
- Medium- and high-voltage transformer protection
- Transformer backup protection
- Industrial power-distribution systems
- Two-winding transformer differential schemes
Procurement Note
For GE Mult, the complete option string matters. W2, P5, G5, and HI are functional configuration identifiers, not cosmetic suffixes. Current references confirm that this exact configuration represents a two-winding, 5 A phase-current, 5 A ground-current relay with the high-voltage control-power option.
For a live transformer protection system, preserve the existing setpoint file, CT/VT data, vector-group compensation, FlexLogic, communication configuration, and firmware information before replacement. A physically compatible without the correct application configuration is not a drop-in functional replacement.
