GE SR745-W2-P5-G5-HI | Transformer Protection Management Relay

• Brand: GE Multilin
• Full Model Number: SR745-W2-P5-G5-HI
• Product Family: Multilin 745 Transformer Management Relay
• Lifecycle Status: Legacy / Obsolescence-managed
• Core Function: Transformer protection, monitoring, metering, and control
• Top 3 Technical Specs: 2 windings per phase | 5 A phase CT inputs | 5 A ground CT inputs
• Control Power: 90–300 VDC / 70–265 VAC, 48–62 Hz
• Logic Inputs: 16
• Communications: Front RS-232; rear RS-485 / RS-422
• Optional Networking: Ethernet configuration depends on exact suffix
• Stock & Condition: New surplus / tested refurbished subject to physical stock verification
• Shipping: Emergency dispatch subject to stock confirmation and carrier cutoff

Obsolescence & Supply Chain Deep Dive

When a transformer protection relay fails, the procurement risk extends beyond the relay itself. Settings, CT ratios, trip logic, SCADA communications, and commissioning records are all tied to the installed protection scheme. The GE Multilin SR745-W2-P5-G5-HI is a two-winding configuration with 5 A phase CT inputs and 5 A ground CT inputs, while the HI power-supply option is specified for 90–300 VDC or 70–265 VAC at 48–62 Hz. Exact suffix verification remains essential because the 745 family uses order-code fields to define hardware and option combinations.

For TCO planning, preserving the installed 745 architecture can avoid the wider engineering scope associated with replacing an entire transformer protection package. Existing CT/VT wiring, trip circuits, panel cutout, communications mapping, and approved protection settings may remain usable after a like-for-like replacement, subject to engineering validation. A documented field test of a 745-W2-P5-G5-HI configuration has also demonstrated relay testing with an Omicron CMC356, including current injection and trip-response verification. That makes secondary-injection testing a practical part of the replacement acceptance process (although the installed relay’s firmware, settings, and option code should be recorded before removal).

Compatibility & Replacement Matrix

Field Traps — Watch Out

• Order-code mismatch: W2 identifies the two-winding configuration, P5 identifies 5 A phase-current inputs, and G5 identifies 5 A ground-current inputs. A visually similar 745 with a different order code should not be approved solely on enclosure compatibility.
• Suffix-dependent features: The base SR745-W2-P5-G5-HI designation does not establish every optional feature. For example, published configurations with an additional T suffix identify Ethernet capability. Confirm the complete installed order code before purchase.
• Firmware/settings: A documented 745 installation shows an order code of 745-W2-P5-G5-HI-AR-E with firmware version 4.0X. Record the installed firmware and option configuration before replacement.

GE SR745-W2-P5-G5-HI

Quality Assurance & Testing SOP

The SR745 is a transformer protection and management relay, so the acceptance procedure should center on protection accuracy, control logic, metering, communications, and trip behavior.

• OEM anti-counterfeit visual inspection: Verify GE/GE Multilin markings, model label, serial number, terminal identification, LCD, keypad, connectors, and enclosure construction.
• Part-number reconciliation: Match the physical nameplate against SR745-W2-P5-G5-HI and document every suffix appearing on the actual unit.
• Configuration inspection: Verify W2, P5, G5, and HI characteristics before electrical testing.
• Mechanical inspection: Examine the drawout mechanism, rear terminals, connectors, mounting points, front-panel controls, and enclosure for damage or contamination.
• Control-power test: Apply the appropriate AC/DC supply under controlled conditions and verify normal startup.
• LCD and LED test: Check display operation, status indicators, alarm indications, keypad response, and diagnostic messages.
• CT-input simulation: Use a calibrated relay test set to inject representative 5 A CT secondary signals and compare measured values with the test source.
• Protection-function testing: Execute applicable overcurrent, differential, ground-fault, thermal, and transformer-protection tests according to the approved site settings and test plan.
• Trip-output testing: Verify relay output operation and timing using a suitable secondary-injection system and, where authorized, the associated trip circuit.
• Analog I/O testing: Where the supplied configuration includes analog I/O, verify each applicable channel across its configured measurement range.
• Communication test: Check the installed serial interface and configured protocol/addressing. Ethernet functions should only be expected where the complete order code includes the applicable option.
• Event and fault-record verification: Confirm event recording, diagnostics, metering, and accessible disturbance information.
• Final QA record: Photograph the actual relay, record serial and firmware information, document test results, and retain the inspection report with the shipment file.

Procurement & Lifecycle FAQ

Is the GE SR745-W2-P5-G5-HI genuinely in stock, and what is the cutoff for emergency shipping?
Physical inventory should be confirmed before PO acceptance. For an emergency requirement, provide quantity and destination early enough to complete identity verification, testing, packaging, and carrier scheduling.

How do you verify the condition and authenticity of a legacy SR745?
The unit should undergo nameplate reconciliation, physical inspection, controlled power-up, display and diagnostic checks, current-input testing, protection-function verification, and applicable communications testing. Actual-unit photographs can be supplied for engineering approval before shipment.

Are there firmware compatibility issues my engineers should check?
Yes. Record the installed relay’s firmware, order code, calibration information, and protection settings before removal. A field record for a 745-W2-P5-G5-HI configuration documents firmware version 4.0X, demonstrating why revision information should form part of the replacement record.

Can replace another GE Multilin 745 directly?
Only after the complete order code has been compared. The W2, P5, G5, and HI fields define important hardware characteristics, while additional suffixes can identify options such as enhanced display, restricted ground fault, conformal coating, or Ethernet.

What warranty and return terms apply?
Warranty duration and return conditions should be stated on the quotation or pro forma invoice for the actual unit supplied. For legacy protection relays, confirm the stated condition, test coverage, warranty period, and return requirements before PO issuance.