ABB REF 542plus  Protective diagnostic controller REF542plus 

• Real-time multifunction protections and switchgear controls: - protections - fault locator - measurements - controls - monitoring and diagnosis - power quality functions - communication - self diagnosis 

• Task separation for implemented protections and control scheme modifications 

• Flexible installation variations due to separated HMI and base unit 

• Large multilingual LCD display for singleline diagram, text messages and menu texts 

• Calculated primary quantities include: - maximum and mean currents in the settable monitoring period 0-30 min - sum of interrupted currents - operating time - number of switching cycles 

• Spring charging time supervision 

• Trip coil supervision 

• Binary input and output modules to interface with external processes 

• Analog input module for primary current and voltage signals: - analog transformers - non-inductive sensors 

• Life Cycle Traceability 

• Optional analog input module 4-20 mA

• Optional analog output module 0(4)-20 mA 

• Optional communication module for the substation automation system 

• Ethernet interface for embedded web server 

• Optional optical input port for time synchronization

 • Part of the ABB Distribution Automation system

Analog inputs 

REF 542plus feeder terminal is designed for connecting to non-conventional current and voltage sensors as well as to instrument transformers. At most 8 analog input channels are available. Due to their linear characteristic, modern current and voltage sensors provide greater accuracy and reliability in signal measurements. Compared to instrument transformers, the new non-inductive sensors have the following advantages: 

• higher linearity 

• high accuracy 

• compact dimensions 

• wide dynamic range 

• easy integration in the panels. 

The current sensor is based on the Rogowsky coil principle and consists of a single airwounded coil. Due to the lack of an iron core, the saturation effects of conventional current transformers do not exist anymore. Current sensors are thus well suited for the deployment of distance and differential protection functions. The voltage sensor is based on the resistive divider principle. Therefore, the voltage sensor is linear throughout the whole measuring range. The output signal is a voltage, directly proportional to the primary voltage.