Description
Key Technical Specifications
- Product Type: Numerical protection and bay control IED for MV switchgear
- Application: Feeder, transformer, and motor protection in GIS/AIS systems
- System Architecture: Multi-processor design (DSP + control + communication processor)
- Auxiliary Supply: 24–250 V DC / 100–240 V AC (typical REF542plus platform range)
- Frequency Rating: 50 / 60 Hz
- CT Inputs: 1 A / 5 A secondary inputs (configurable)
- VT Inputs: 100–110 V AC nominal (variant dependent)
- Protection Functions: Overcurrent (50/51), earth fault (50N/51N), directional elements (67/67N), thermal protection
- Fault Response Time: Sub-20 ms class for instantaneous protection elements
- Communication Protocols: IEC 61850, Modbus RTU/TCP, DNP3 (variant dependent)
- HMI Interface: Local LCD keypad panel with status LEDs
- I/O Architecture: Modular binary inputs and relay outputs (card dependent)
- Event Recording: Disturbance recorder with time-stamped fault logs
- Mounting: Flush-mounted switchgear door installation
- Operating Temperature: −25°C to +70°C (typical industrial envelope)
Product Introduction
ABB REF542PLUS 76A2NFFN301WS28 is a legacy medium-voltage protection and bay control IED used in feeder and transformer switchgear systems. The REF542plus platform integrates protection algorithms, control logic, measurement, and substation communication into a single modular architecture for GIS and AIS applications.
The 76A2NFFN301WS28 configuration typically reflects a project-specific hardware build, meaning I/O, communication, and firmware behavior must always be verified against the original commissioning documentation. In field work, mismatch between firmware revision and communication modules causes more downtime than actual relay failure.
