Description
Product Introduction
A transformer differential-protection trip can take a critical power asset out of service, and replacing the relay without matching its current-input and control-power configuration can extend the outage. The GE Multilin 745-W2-P5-G5-LO-A-L-R-E is a two-winding transformer protection relay designed for protection and monitoring applications in industrial and utility power systems.
Its ordering code specifies 5 A phase and ground current inputs, low-range control power, analog I/O, loss-of-life monitoring, restricted ground-fault protection, and an enhanced display. For procurement, verify the complete configuration and application settings before treating this GE 745 transformer relay as a replacement for an installed unit.
Key Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | GE Multilin |
| Model | 745-W2-P5-G5-LO-A-L-R-E |
| Product family | 745 Transformer Protection System |
| Relay type | Transformer protection and management relay |
| Winding configuration | W2 — two windings per phase |
| Phase CT input rating | P5 — 5 A for each applicable winding |
| Ground CT input rating | G5 — 5 A for applicable ground-current inputs |
| Control power | LO — 20–60 VDC or 20–48 VAC, 48–62 Hz |
| Analog I/O | A — analog input/output option |
| Loss-of-life function | L — loss-of-life monitoring option |
| Restricted ground fault | R — restricted ground-fault option |
| Display | E — enhanced display |
| Ethernet | Do not infer Ethernet from the E suffix; confirm the exact order-code configuration |
| Installation | Panel-mounted relay in the applicable SR-family case |
| Operating temperature | Verify the applicable manual and installation requirements |
The low-range control-power designation is specific to the relay’s auxiliary supply. It is not the voltage rating of the transformer measurement inputs. GE’s 745 documentation distinguishes the LO and HI control-power options and identifies T, rather than E alone, with the enhanced-display-plus-Ethernet configuration.
Application Scenarios & Pain Points
The important field issue is not simply whether a replacement relay powers up. It must also match the transformer CT circuits, protection settings, and trip logic.
- Power transformer differential protection: Compare the existing winding configuration and CT secondary ratings before connecting current-transformer circuits.
- Restricted ground-fault protection: Confirm that the
Roption is present and that the application wiring and protection settings support the intended scheme. - Transformer condition monitoring: The
Loption supports loss-of-life monitoring; confirm that the required thermal and loading inputs are available and correctly configured. - Control-panel replacement: Check auxiliary supply voltage, terminal assignments, communication requirements, and case compatibility before scheduling a swap.
Field note: if a relay has tripped repeatedly, capture the event records and disturbance information before replacing it where site procedures permit. A replacement may restore hardware availability, but it will not correct a CT polarity error, unsuitable setting, or wiring fault.
745-W2-P5-G5-LO-A-L-R-E
Related Products
These related models belong to the GE Multilin 745 transformer-protection family or adjacent configurations. They are not automatically interchangeable.
- 745-W2-P5-G5-LO — Two-winding relay configuration with 5 A phase and ground inputs and low-range control power; optional functions may differ.
- 745-W2-P5-G5-HI-A — Two-winding version with 5 A current inputs, high-range control power, and analog I/O.
- 745-W2-P1-G1-LO-E — Two-winding configuration with 1 A phase and ground inputs; current-transformer interface differs from the target model.
- 745-W3-P5-G5-HI-A — Three-winding configuration with 5 A current inputs and high-range control power.
- 745-W2-P15-G1-LO-A-R — Mixed phase-current input configuration; check winding-by-winding CT ratings carefully.
- 745-W2-P5-G5-HI-A-L-R-E — Similar option set with high-range control power rather than the target’s low-range supply.
These distinctions follow the documented 745 ordering scheme. Match the full suffix, not just the 745-W2 family prefix.
Engineer’s Guide: Three Replacement Checks
1. Match CT ratings and winding configuration. The target uses 5 A phase and ground current inputs and is configured for two windings per phase. Confirm the actual transformer connections and CT secondary ratings against the approved drawings. Never select a 1 A variant simply because its front panel looks similar.
2. Verify the auxiliary supply and option codes. The LO configuration is rated for 20–60 VDC or 20–48 VAC at 48–62 Hz. Check the supply at the relay terminals and confirm the required A, L, R, and E functions before ordering. Do not assume the E suffix means Ethernet.
3. Plan the protection-setting transfer and commissioning. Back up settings and records where possible, then validate differential protection, restraint characteristics, CT polarity and ratios, ground-fault logic, trip outputs, and alarms under the site’s approved commissioning procedure. A matching catalog number alone does not establish that the protection scheme is correctly configured.
Frequently Asked Questions
What is the GE 745-W2-P5-G5-LO-A-L-R-E used for?
It is a GE Multilin 745 transformer protection relay used in transformer protection and management systems. Its configuration includes two windings per phase, 5 A phase and ground current inputs, analog I/O, loss-of-life monitoring, restricted ground-fault protection, and an enhanced display.
What does W2-P5-G5 mean?
W2 identifies two windings per phase. P5 specifies 5 A phase-current inputs for the applicable windings, and G5 specifies 5 A ground-current inputs. These designations must match the installed CT circuits.
What is the control-power range for the LO version?
The documented low-range option supports 20–60 VDC or 20–48 VAC at 48–62 Hz. Check the actual supply and nameplate before energizing the relay.
Does this model include Ethernet?
Do not assume that it does. The 745 ordering information identifies E as an enhanced-display option and T as enhanced display plus a 10Base-T Ethernet port. Confirm the complete ordered configuration and available communications interfaces before connecting it to a network.
Can I replace it with a 745 relay that has a similar part number?
Only after confirming the winding configuration, phase and ground CT ratings, control-power range, installed options, case requirements, and application settings. A 1 A CT-input model or a high-range control-power version is not an equivalent substitute by default.
How should I verify a used or refurbished relay?
Request photographs of the full model label, terminal connections, case, and any revision markings. Ask for a documented functional test, confirmation of the fitted options, and written warranty terms. For a protection relay, a power-on check alone is not adequate evidence that the protection functions operate correctly.
What information should I send when requesting a quotation?
Provide the complete model number, transformer application, required condition, photographs of the installed unit, control-power source, CT secondary ratings, and delivery deadline. Ask the supplier to confirm the exact option configuration, stock status, warranty, and lead time in writing.
Procurement recommendation: The most important checks for this model are the 5 A CT interface, low-range auxiliary supply, and installed protection options. Confirm those details against the existing relay and approved protection documentation before placing an order.
