GE Multilin SR745 Transformer Management Relay 745-W3-P5-G5-HI-A-L-R-E-H Ready For Ship

The GE 745‑W3‑P5‑G5‑HI‑A‑L‑R‑E‑H is a microprocessor‑based digital relay designed by GE Multilin for primary and backup protection of three‑winding power transformers, autotransformers, and reactors. Part of the renowned SR series, the 745‑W3‑P5‑G5‑HI‑A‑L‑R‑E‑H integrates dual‑slope percentage differential protection with second‑ and fifth‑harmonic inrush blocking, restricted ground fault detection, and comprehensive overcurrent and overexcitation (V/Hz) elements within a single drawout case. The 745‑W3‑P5‑G5‑HI‑A‑L‑R‑E‑H features an enhanced 40‑character backlit LCD, conformal coating for corrosive environments, wide‑range high‑level control power, and full Modbus/DNP 3.0 communication capability. With FlexLogic™ programmable logic, auto‑CT configuration, loss‑of‑life monitoring, and IRIG‑B time synchronization, the 745‑W3‑P5‑G5‑HI‑A‑L‑R‑E‑H delivers intelligent, maintenance‑reducing protection for demanding utility and industrial substations.

• Three‑winding power transformers – primary differential protection and management for small, medium, and large units with three separate windings

• Generator step‑up (GSU) transformers – comprehensive backup protection for generator‑transformer units

• Autotransformers – differential and restricted ground fault protection

• Reactors – overload and fault detection for shunt or series reactors

• Dual‑secondary transformers – independent protection for each secondary winding

• Transformers with dual‑breaker source terminals – breaker‑and‑a‑half or ring bus configurations

• Substation automation – stand‑alone or integrated into bay‑level control systems

• Industrial power distribution – refineries, chemical plants, steel mills, data centers

• Renewable energy plants – solar, wind, and hydro power transformers

• Critical grid infrastructure – where high reliability and rapid fault clearance are required

• Three‑winding differential protection – dual‑slope percentage differential (87T) with independent slope‑1 (15‑100%), slope‑2 (50‑100%), and adjustable kneepoint (KP) for superior sensitivity and through‑fault stability

• Adaptive harmonic inrush blocking – second harmonic, second+5th, and energization‑based restraint methods prevent maloperation during magnetizing inrush while maintaining speed for internal faults

• Fifth harmonic overexcitation inhibit – dedicated element blocks differential tripping during V/Hz overexcitation events

• Unrestrained instantaneous differential – trips without intentional delay for heavy internal faults to limit equipment damage

• Restricted ground fault (RGF) – zero‑sequence differential for sensitive detection of low‑magnitude ground faults in star‑connected windings

• Full overcurrent suite – phase, neutral (3I₀), ground, and negative‑sequence elements with IOC/TOC curves: IEEE, IEC, GE IAC, definite time, and FlexCurves™

• Auto‑CT configuration – all CTs connected wye; relay automatically corrects phase angle, magnitude, and zero‑sequence compensation without external interposing CTs

• Dynamic CT ratio mismatch correction – monitors and compensates for on‑load tap changer (OLTC) variations in real time

• Transformer loss‑of‑life monitoring – estimates hottest‑spot temperature, aging factor, and remaining insulation life per IEEE C57.91‑1995 / C57.96‑1989

• Comprehensive frequency protection – underfrequency (2 elements), overfrequency (1 element), frequency rate‑of‑change (4 elements) for advanced load shedding

• Voltage protection suite – overexcitation (V/Hz) with definite‑time or IEC curves, undervoltage, and overvoltage elements

• Four independent setting groups – selectable via logic inputs, front panel, or communications for different system configurations

• FlexLogic™ programmable logic engine – user‑defined protection and control schemes (interlocking, dynamic setting group changes, permissive tripping) without external wiring

• Fully drawout case with automatic CT shorting – relay portion slides out for bench testing or replacement without de‑energizing the main circuit, minimizing downtime

• Conformal coating (-H suffix) – factory‑applied polymer layer protects PCB from humidity, airborne contaminants, and mild chemical corrosion for harsh industrial environments

• High‑resolution 64 samples/cycle sampling – enables harmonic analysis up to the 21st harmonic, THD calculation, and harmonic derating factor (ANSI/IEEE C57.110‑1986)

• Field‑upgradeable firmware – new features and updates can be added in the field without replacing hardware

• Simulation mode with waveform playback – test relay logic and settings by injecting arbitrary waveform data from computer‑generated files

• High‑speed event and fault recording – 128 time‑tagged events (1 ms resolution), 10 oscillography records (32 power cycles each, COMTRADE format), and data logger for post‑event analysis

• IRIG‑B time synchronization – GPS‑synchronized timestamping across substations for coordinated event analysis

• Multi‑port communication – front RS232 for local laptop connection; dual rear RS485/RS422 ports (Modbus RTU, DNP 3.0 Level 2); optional 10BaseT Ethernet (Modbus TCP/IP)

• EnerVista 745 Setup software – single environment for configuration, monitoring, diagnostics, waveform viewing, and event retrieval; supports offline setpoint file creation and management

• Security audit trail – logs all configuration changes for regulatory compliance and troubleshooting traceability

• Wide‑range control power (HI) – 90‑300 V DC or 70‑265 V AC, 48‑62 Hz, eliminating external converters for retrofit projects

• 40‑character enhanced backlit LCD and keypad – intuitive local navigation through setpoints, actual values, and target messages

• 20 LED status indicators – real‑time visual feedback for relay health, system status, and trip/alarm conditions

• Security password protection – restricts unauthorized setpoint changes and tampering

• Harmonic monitoring – measures individual harmonics up to the 21st, THD (IEEE 519‑1986), and Harmonic Derating Factor

• Detects internal transformer faults – compares differential current against dual‑slope bias with harmonic restraint (2nd, 2nd+5th, energization‑based), issuing trip commands while ignoring inrush and overexcitation

• Clears high‑magnitude faults rapidly – unrestrained differential element trips without intentional delay for heavy internal faults to limit equipment damage

• Senses low‑magnitude ground faults – restricted ground fault (zero‑sequence differential) detects faults close to the neutral point in star‑connected windings

• Provides backup overcurrent protection – phase, neutral, ground, and negative‑sequence IOC/TOC elements with selectable curve shapes (IEEE, IEC, IAC, FlexCurves™) for coordination with downstream devices

• Prevents core overheating – V/Hz overexcitation protection (2 elements) with definite‑time or IEC curves

• Supports load shedding and islanding detection – underfrequency (2 elements), overfrequency, and frequency rate‑of‑change (4 elements) elements with programmable thresholds

• Monitors transformer asset health – calculates hottest‑spot temperature, aging factor, and remaining insulation life per IEEE standards for predictive maintenance planning

• Executes custom automation logic – FlexLogic™ engine performs local interlocking, dynamic setting group switching, and permissive tripping without external relays or PLCs

• Records fault and sequence‑of‑events data – captures 128 time‑tagged events (1 ms accuracy), 10 oscillography records (32 power cycles), and data logs; retrievable via front panel or EnerVista software

• Automatically configures CT inputs – corrects phase angle, magnitude, and zero‑sequence compensation automatically for simplified transformer setup

• Synchronizes to GPS time – IRIG‑B input enables precise timestamping across the substation for coordinated event analysis

• Communicates with SCADA/DCS – transmits real‑time metering data, protection status, fault records, and oscillography via Modbus RTU, DNP 3.0 Level 2, or optional Modbus TCP/IP

• Enables offline relay testing – simulation mode allows waveform playback without applying live power, verifying protection logic before commissioning