ABB REF542PLUS 1VCR007346｜Protection Relay｜

REF542

The ABB REF 542plus feeder terminal is designed to interface with both non-conventional current and voltage sensors as well as traditional instrument transformers (CTs and VTs).

The unit supports up to 8 analog input channels, allowing flexible measurement configurations for protection, control, and monitoring applications in medium-voltage switchgear systems.

Advantages of Non-Conventional Current and Voltage Sensors

Modern current and voltage sensors provide improved measurement performance due to their highly linear characteristics. Compared with conventional instrument transformers, non-inductive sensors offer several advantages:

Feature Benefit
Higher linearity Provides consistent measurement accuracy over a wide operating range
High accuracy Improves protection sensitivity and measurement reliability
Compact dimensions Requires less installation space inside switchgear panels
Wide dynamic range Enables accurate measurement from low load currents to high fault levels
Easy panel integration Simplifies switchgear design and installation

These characteristics make modern sensors particularly suitable for advanced protection functions, including distance protection and differential protection.

Current Sensor Technology – Rogowski Coil Principle

The REF 542plus supports current measurement using sensors based on the Rogowski coil principle.

The current sensor consists of:

A single air-core, air-wound coil
No magnetic iron core
Linear current measurement characteristics

Because the sensor does not contain an iron core, it eliminates the saturation effects commonly associated with conventional current transformers (CTs).

Benefits of Rogowski Coil Current Sensors
No magnetic saturation during high fault currents
Improved measurement linearity
Excellent transient response
Suitable for high-performance protection applications

Due to these characteristics, current sensors are especially suitable for:

Distance protection functions
Differential protection functions
High-speed fault detection applications
Voltage Sensor Technology – Resistive Divider Principle

The REF 542plus voltage measurement interface supports voltage sensors based on the resistive divider principle.

The voltage sensor provides:

A linear output across the complete measurement range
A low-voltage output signal proportional to the primary system voltage

The output signal is directly proportional to the measured primary voltage, enabling accurate voltage monitoring and protection calculations.

Key Advantages of Resistive Voltage Sensors
High measurement linearity
Stable performance over the complete voltage range
Compact design compared with conventional voltage transformers
Reliable input signals for protection and automation functions
Application Benefits

By supporting both conventional instrument transformers and modern non-conventional sensors, the REF 542plus feeder terminal provides:

Flexible switchgear design options
Improved measurement accuracy
Reduced panel space requirements
Enhanced protection performance
Reliable integration of advanced protection functions