Description
Technical Specifications
- Product Model: SR745
- Brand: GE Multilin (GE Vernova)
- Warranty: One Year
- Input Voltage: 70‑265 V AC / 90‑300 V DC wide‑range auxiliary supply
- Operating Temperature: ‑40 °C to +60 °C
- Storage Temperature: ‑40 °C to +80 °C
- Response Time: ≤30 ms differential primary trip operate time
- Protection Class: IP54 front panel, IP20 rear terminals (draw‑out case)
- Accuracy Class: Class 0.2S for protection‑grade metering measurement
- Output Frequency: 50 / 60 Hz adaptive system frequency support
- Rated Current Range: 1‑5 A CT secondary input
- Communication Interface: Front‑panel RS232, rear‑mounted RS422/RS485, optional 10 Mbps Ethernet port
- Supported Protocols: Modbus RTU, Modbus TCP, DNP3.0 Level 2
- Overload Capacity: 20× rated secondary current for 1 second short‑time withstand
- Dimensions: 267 mm × 178 mm × 241 mm, 19‑inch rack‑mount draw‑out chassis
Product Overview
The GE SR745 is a multifunctional transformer management and protection IED from the Multilin product line, built for two‑winding, three‑winding transformers, autotransformers and shunt reactors within utility substations and industrial power plants. This draw‑out‑format intelligent electronic device integrates percentage‑biased differential protection, inrush‑restraint logic, restricted earth‑fault protection, backup overcurrent, V/Hz over‑excitation supervision, tap‑changer control, thermal‑overload monitoring, disturbance recording and transformer loss‑of‑life asset assessment into one hardware unit. It addresses common substation pain points including false tripping caused by magnetizing inrush, incomplete transformer winding‑fault coverage, limited insulation‑ageing monitoring and multi‑vendor SCADA interoperability challenges. Protection engineers, substation integrators and power‑plant maintenance teams benefit from this relay; draw‑out mechanical design allows hot‑swap spare replacement without full cabinet power‑down, while built‑in thermal‑life calculation delivers actionable predictive‑maintenance data for transformer assets. It supports both green‑field substation deployments and retrofit upgrades for ageing transformer‑protection installations.
Application Scenarios
- Utility Substation Main Transformer Primary Protection: Deployed as main differential protection for station power transformers. Dual‑slope differential algorithm and inrush‑blocking logic prevent nuisance tripping during transformer energisation; restricted earth‑fault elements provide sensitive detection for internal winding‑to‑ground faults.
- Industrial‑Plant & Cogeneration‑Facility Transformer Protection: Used for step‑down and generator‑step‑up transformers inside refineries, steel mills and CHP plants. Thermal‑overload and loss‑of‑life monitoring tracks transformer insulation ageing, supporting asset‑management and load‑limiting operational decisions.
- Autotransformer & Shunt Reactor Protection: Configured for autotransformer and large shunt‑reactor bays. V/Hz over‑excitation protection mitigates core‑saturation risk, and multi‑winding differential logic covers complex multi‑terminal power‑equipment fault conditions.
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