ABB REF543KB127AAAA is a feeder protection and control relay from ABB’s REF 543 series, designed for medium-voltage distribution systems.

1. Product Positioning

This device belongs to the ABB Relion / REF 543 platform and is used for feeder protection and substation automation in:

• Medium-voltage distribution networks (approx. 6–35 kV)
• Substation feeder protection applications
• Industrial power distribution systems (factories, mining, energy, etc.)

2. Main Functions

Protection functions

• Overcurrent protection (50/51)
• Earth-fault protection (50N/51N)
• Overvoltage / undervoltage protection
• Overfrequency / underfrequency protection
• Phase failure and negative-sequence protection
• Automatic reclosing (auto-reclose)
• Capacitor bank / motor protection (depending on configuration)

Measurement and monitoring

• Three-phase current and voltage measurement
• Power and energy calculation
• Harmonics and power quality analysis
• Fault recording and event logging (SOE)

Control functions

• Circuit breaker open/close control
• Logic interlocking (built-in PLC-like functionality)
• Feeder sectioning and automation

Communication capabilities

• IEC 61850 (GOOSE / MMS)
• Modbus RTU
• DNP3
• IEC 60870-5-103
• Profibus (via adapter)

3. Key Features

• Fast tripping time (typically < 50 ms)
• Suitable for various grounding systems (isolated, compensated, or resistance grounded)
• Programmable logic functionality, reducing the need for external PLCs
• Compatible with SCADA / DCS systems
• Industrial-grade design with operating temperature from -40°C to +70°C

4. Applications

• Substation feeder protection
• Wind and solar power grid integration
• Industrial power systems (steel, chemical, mining)
• Capacitor bank and motor protection
• Smart grid and distribution automation systems