Description

ABB REF543KM127AAAA (Relion® 500 Series Medium Voltage Feeder / Motor Protection Relay)
REF543KM127AAAA is a multi-functional medium voltage protection relay (IED) of ABB Relion® 500 series, designed for ≤40.5kV industrial / power grid systems. It focuses on comprehensive protection of motors and feeders, equipped with arc detection and IEC 61850 digital communication.

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Basic Information
Brand: ABB (Sweden)
Model: REF543KM127AAAA
Series: Relion® 500 / REF54x Platform
Type: Digital protection and control device (Feeder Terminal)
Application: Medium-voltage feeder, motors, transformers, capacitors protection and control
Installation: Panel-mounted (standard cabinet)
Weight / Dimensions: Approximately 4.3 kg; 263 × 58 × 280 mm
Core model meaning (KM127AAAA)
K: Enhanced motor protection (Motor)
M: Standard protection configuration
127: 110–240V AC/DC power supply; 5A current input
AAAA: Basic version, no special customization
Main protection functions
Overcurrent / Fast break: Directional / Non-directional (50/51, 50N/51N)
Motor-specific: Thermal overload (49), Overload, Unbalance / Negative sequence, Ground fault
Arc light detection: <5ms trip, Bus / Switchgear protection
Voltage protection: Overvoltage / Undervoltage, Phase sequence, Frequency (59/27, 81)
Others: Ground fault, Power direction, Zero sequence protection

Communication and Interfaces
Ethernet: IEC 61850 Ed.2 (GOOSE/SV), Modbus TCP
Serial Port: Modbus RTU, DNP3.0
Time Synchronization: IRIG-B, SNTP
Local: Backlit LCD, Keys, LED Status Indicators
Electrical and Environmental
Operating Power Supply: 110–240V AC/DC (±20%)
Current Input: 1A / 5A (optional)
Voltage Input: Up to 690V (via VT)
Temperature: -25°C ~ +55°C
Protection: IP20 (Enclosure)
Certifications: CE, UL, IEC 61000, IEEE C37.90
Typical application
Industrial ** Medium Voltage Motors (3–10kV) ** Comprehensive Protection (such as fans, pumps, compressors)
Substation feeder, transformer, capacitor bank protection
Digital Substation IEC 61850 Networking
Switchgear Arc Flash Rapid Protection System
Replacement / Compatible Models
REF543KM127BAAA: Hardware is the same, but firmware / configuration version is different
REF543KB127AAAA: Basic feeder protection (without enhanced motor function)