Description
Key Technical Specifications
| Parameter | Value |
|---|---|
| Manufacturer | GE Multilin |
| Model | SR745-W2-P5-G5-HI |
| Product Family | Multilin 745 |
| Product Type | Transformer Protection & Management Relay |
| Transformer Configuration | Two windings per phase (W2) |
| Phase CT Input | 5 A secondary (P5) |
| Ground CT Input | 5 A secondary (G5) |
| Control Power | 70–265 V AC, 48–62 Hz or 90–300 V DC (HI) |
| Protection Functions | Differential, overcurrent, ground fault, restricted ground fault (depending on option code), overexcitation, thermal monitoring |
| Metering | Current, voltage, power, frequency, event recording |
| Communications | Configurable communication options depending on ordered hardware |
| Mounting | SR745 draw-out case / panel installation |
| Country of Manufacture | Canada |
| Weight | Approximately 7.5 kg (16.6 lb) |
Product Introduction & Supply Chain Strategy
The GE Multilin SR745-W2-P5-G5-HI is a microprocessor-based transformer protection relay designed for medium- and high-voltage two-winding power transformers. It integrates differential protection, backup overcurrent protection, metering, diagnostics, event recording, and control functions within a single intelligent electronic device (IED), making it suitable for utility substations and industrial power systems.
From an inventory perspective, the Multilin 745 platform remains widely installed despite its mature lifecycle. Procuring New Surplus inventory helps reduce Total Cost of Ownership (TCO), limits lead time variability, and avoids the reliability risks associated with refurbished electronics. For critical substations, maintaining 1–2 units of buffer stock and implementing a last-time-buy strategy is recommended before genuine inventory becomes scarce.
Installation & Configuration Guide
Stage 1 – Pre-Installation (Preparation & Safety)
- Perform Lock-Out/Tag-Out (LOTO) procedures.
- De-energize all control and CT/PT circuits.
- Wear a grounded ESD wrist strap.
- Photograph:
- CT and VT wiring
- Digital input/output wiring
- Communication connections
- Hardware option modules
- Upload and back up the existing relay settings before removal.
Stage 2 – Removal
- Label every terminal connection.
- Disconnect communication and field wiring.
- Release the relay from its draw-out case.
- Inspect all connector pins for contamination or damage.
Stage 3 – Installation
- Verify the replacement model is SR745-W2-P5-G5-HI.
- Install the relay into the existing case until fully seated.
- Restore all wiring exactly as documented.
- Download the saved configuration.
- Confirm CT and VT ratios before energizing.
Stage 4 – Power-On & Testing
- Apply control power.
- Verify normal relay self-test completion.
- Confirm all LEDs and LCD indications.
- Test communications with the SCADA or DCS.
- Perform secondary injection testing to verify transformer protection functions before returning the transformer to service.
Firmware / Software Versions & Upgrade Notes
- Record the existing firmware revision before replacing the relay.
- Restore the original settings file whenever possible to minimize commissioning time.
- Verify firmware compatibility with the installed communication protocol and supervisory control system.
- Avoid upgrading firmware during emergency maintenance unless required to resolve a known compatibility issue.
- After any firmware change, validate protection settings, event recorder functions, and communication mapping before placing the relay into operation.
- SR745-W2-P5-G5-HI
- SR745-W2-P5-G5-HI
Frequently Asked Questions (FAQ)
Q1. Is this a New Original product?
Yes. This product should be supplied as New Original / New Surplus. It is not used, repaired, or refurbished. Each unit should undergo serial number verification, electrical inspection, and functional quality checks before shipment.
Q2. Why is New Surplus priced between OEM new and refurbished equipment?
New Surplus inventory consists of genuine unused OEM hardware obtained from surplus industrial stock. It offers OEM reliability while typically costing less than current factory pricing, making it a lower-risk alternative to refurbished units.
Q3. Is the SR745-W2-P5-G5-HI still an active product?
The Multilin 745 platform is considered a mature legacy protection system. Although many units remain in service worldwide, genuine new inventory is increasingly limited, making proactive spare-part planning advisable.
Q4. Can the relay be hot-swapped?
No. Always isolate control power and follow substation safety procedures before removing or installing the relay. Hot swapping can result in protection system failure or equipment damage.
Q5. Will replacing the relay affect protection settings?
If the existing configuration has been backed up, settings can normally be restored to the replacement unit. Always verify CT ratios, protection logic, communication parameters, and relay outputs after downloading the configuration.
Q6. What warranty is appropriate for New Surplus inventory?
A qualified industrial automation supplier typically provides a 12 month warranty, complete incoming inspection, serial number verification, functional testing, and ESD-safe packaging.
Q7. What inventory strategy is recommended?
For substations and industrial facilities where transformer outages have a high operational cost, maintain 1–2 New Surplus relays as buffer stock. Because this is a mature product family, organizations should monitor lead time variability, consolidate qualified suppliers, and evaluate last-time-buy opportunities to reduce long-term procurement risk.
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