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Description
Technical Specifications
| Parameter Name | Parameter Value |
|---|---|
| Product Model | 745-W3-P511-G51-HI-R-E |
| Manufacturer | GE Multilin (GE Grid Solutions / GE Vernova) |
| Product Type | Transformer Management Relay / Numerical Protection Relay |
| Applicability | Two- and three-winding transformers, autotransformers, reactors |
| Winding Configuration | W3 — three windings per phase |
| Phase Current Inputs | P511 — Winding 1 = 5 A, Winding 2 = 1 A, Winding 3 = 1 A |
| Ground Current Inputs | G51 — Winding 1/2 = 5 A, Winding 2/3 = 1 A |
| CT Primary Range | 1 to 50,000 A primary; 1 A or 5 A secondary |
| Current Input Burden | Less than 0.2 VA per phase at rated |
| Current Conversion Range | 0.02 to 46 × CT |
| Current Measurement Accuracy | ±0.25% below 4 × CT; ±0.5% above 4 × CT |
| Current Overload Withstand | 1 s at 80 × rated; 2 s at 40 × rated; continuous at 3 × rated |
| Voltage Inputs | 60 to 120 V phase-to-neutral; max continuous 273 V; VT ratio 1 to 5000 |
| Voltage Input Burden | Less than 0.025 VA at 120 V |
| Control Power | HI — 90 to 300 V DC; 70 to 265 V AC at 48 to 62 Hz |
| Control Power Consumption | 30 VA nominal, 40 VA maximum |
| Internal Fuse | 3.15 A, 5 × 20 mm slow-blow, high breaking capacity |
| Frequency | 50/60 Hz nominal; tracking range 2 to 65 Hz |
| Logic Inputs | 16 (dry contacts 1000 Ω max ON; wet contacts 30 to 300 V DC) |
| Output Relays | 8 (solid-state plus Form-A trip-rated and Form-C auxiliary contacts) |
| RTD Inputs | 3-wire, 100 Ω Platinum (DIN 43760), 100 Ω Nickel, 120 Ω Nickel |
| IRIG-B Input | 1.0 to 10 V pk-pk amplitude modulated or TTL DC shift; 70 to 100 kΩ |
| Communications | RS232 front, RS485/RS422 rear, 10Base-T Ethernet |
| Protocols | Modbus RTU, Modbus TCP/IP, DNP 3.0 Level 2 |
| Display | Enhanced 40-character backlit LCD with keypad |
| Dielectric Strength | 2 kV for 1 s per IEC 255-5 and ANSI/IEEE C37.90 |
| Operating Temperature | −40 °C to +60 °C |
| Dimensions (H × W × D) | Approx. 21.5 × 23 × 25.2 cm (draw-out SR-series case) |
| Weight | Approx. 7.6 kg |
| Mounting | Panel flush-mount or 19-inch rack, draw-out case with CT auto-short |
| Lifecycle Status | Discontinued by GE; Multilin 845 relay is the recommended alternative |
Main Features and Advantages
Percentage-restrained differential with harmonic restraint: The core of the GE Multilin 745-W3-P511-G51-HI-R-E is its biased differential element, which compares current entering and leaving each winding and restrains on through-fault current so that external faults do not trip a healthy transformer. Second-harmonic blocking prevents operation on magnetising inrush during energisation, and fifth-harmonic blocking guards against overexcitation. Adaptive harmonic restraint and dynamic CT ratio mismatch correction mean the relay compensates for ratio and phase-shift errors rather than forcing the protection engineer to accept a degraded setting.Restricted ground fault for internal earth faults: The R option in the GE Multilin 745-W3-P511-G51-HI-R-E enables a ground differential element that detects winding-to-earth faults far more sensitively than a plain overcurrent function can. This is the element that catches the faults a standard differential element may see only weakly, and it is the reason many utilities specify the R option as standard on important transformers.Three-winding coverage in one device: With W3, the GE Multilin 745-W3-P511-G51-HI-R-E protects all three windings within independent differential zones, plus the backup package — phase, neutral and ground time overcurrent, overfluxing, thermal replica, under- and over-voltage, frequency and breaker-failure logic. That replaces a panel of discrete electromechanical relays with a single draw-out unit.Forensics that actually settle arguments: Oscillography capture, a time-stamped event recorder and IRIG-B time synchronisation mean that after a trip the question of what happened, and in what order, can be answered from data rather than inferred. Data logger and waveform simulation features let engineers replay recorded events through the relay to verify settings.Asset management and communications: Twelve RTD inputs feed thermal monitoring of windings and oil, and FlexLogic allows custom scheme logic without external interposing relays. Modbus RTU, Modbus TCP/IP and DNP 3.0 Level 2 give straightforward SCADA integration over RS485 or Ethernet.A caution on inflated claims: Some resellers advertise IEC 61850 for the 745. GE’s own product documentation lists only Modbus and DNP 3.0 Level 2 for this platform. Buy against the official function list.
Application Field
Utility transmission and distribution substations are the primary territory for the GE Multilin 745-W3-P511-G51-HI-R-E. It is specified as main protection on HV/MV power transformers, and equally as the replacement for ageing electromechanical differential schemes that are no longer supportable. The draw-out case matters here: a relay can be withdrawn for testing without disturbing CT wiring, because the case automatically shorts the CT circuits on withdrawal.Three-winding and autotransformer applications are where the W3 configuration earns its place. Tertiary-winding transformers, station service transformers with a delta tertiary, and interconnecting autotransformers all present the problem that the GE Multilin 745-W3-P511-G51-HI-R-E is configured to solve — three sets of CTs with different ratios and phase relationships, resolved in one device rather than across several.Heavy industry uses the same relay on the incoming and unit transformers at steel mills, cement works, chemical plants, mines and large automotive facilities, where a transformer outage stops production and a transformer failure is a capital loss. Oil and gas installations apply it at refinery substations, offshore platform transformers and pipeline compressor stations. Renewable generation uses it on wind farm collector transformers and solar step-up transformers, where inrush events are frequent and harmonic restraint is not optional.Increasingly, though, the dominant application is continuation. The GE Multilin 745-W3-P511-G51-HI-R-E is now a legacy spares problem: sites with a validated, understood, operating fleet of 745 relays are buying tested units to defer a migration they have not yet funded.
Related Products
745-W3-P511-G51-HI-R-E-H — the same configuration with the H option adding harsh-environment conformal coating for humid or chemically corrosive locations.745-W3-P5-G5-HI-R-E — the uniform 5 A variant, with 5 A phase and ground CT inputs on all windings; the configuration to specify when every CT is 5 A.745-W2-P5-G5-HI-R-E — the two-winding version of the same relay for standard two-winding transformers.745-W3-P1-G1-HI-R-E — the all-1 A CT version, matched to installations with 1 A CT secondaries throughout.745-W3-P511-G51-HI-A-L-R-E — the fully optioned build adding analog inputs and outputs (A) and loss-of-life and insulation aging assessment (L).745-W3-P5-G5-LO-R-E — the low-voltage control power variant at 20 to 60 V DC and 20 to 48 V AC, for stations with 48 V battery systems.Multilin 845 — GE’s designated alternative now that 745 manufacturing has ceased; the migration path for new projects and panel replacements.Multilin T60 — the transformer protection relay from the UR platform, offering a larger I/O and communications feature set for complex applications.Multilin SR750 / SR760 — feeder and transformer protection relays covering smaller distribution transformers where a full 745 is oversized.EnerVista 745 Setup — the engineering software used to configure, commission and maintain the 745-W3-P511-G51-HI-R-E, including setpoint file management and event retrieval.
