The ABB REF543 is a feeder protection relay from the REF 54x series, designed for medium-voltage distribution networks. Below are the key technical parameters for the REF543KM129AAAB variant:

General Specifications:

• Model: REF543 (KM129AAAB denotes specific hardware/software configuration)
• Application: Feeder protection, motor protection, and transformer protection
• Housing: Standard 19-inch rack or panel mounting (IP40/IP52)

Electrical Parameters:

• Rated Voltage (Auxiliary Supply):
  • DC: 24–250 V
  • AC: 48–250 V
• Current Inputs:
  • Rated Current (Iₙ): 1 A or 5 A (configurable)
  • Thermal Withstand: 4× Iₙ continuously, 100× Iₙ for 1s
• Frequency: 50/60 Hz

Protection Functions:

• Overcurrent Protection (50/51, 50N/51N, 50G/51G)
• Directional Overcurrent (67, 67N)
• Earth Fault Protection (50EF/51EF, 67N)
• Thermal Overload Protection (49)
• Motor Protection (46, 49, 66) (if applicable)
• Autoreclosing (79) (optional)

Communication & I/O:

• Communication Protocols:
  • IEC 61850, Modbus RTU/TCP, DNP3, IEC 60870-5-103
• Binary Inputs: Up to 14 (programmable)
• Binary Outputs: Up to 10 (relay contacts)
• Ethernet Ports: 2× (for IEC 61850 & SCADA)

Environmental & Mechanical:

• Operating Temperature: -25°C to +60°C
• Ingress Protection: IP40 (standard), IP52 (optional)
• Mounting: 19-inch rack or panel