Glossary of Terms

ABR – Automatic Backfeed Restoration

This function generates an automatic close of the recloser if supply is applied to one side of normally open recloser and another side of recloser has no voltage.

ACR - Automatic Circuit Recloser

An Automatic Circuit Recloser is a circuit breaker incorporating a multishot, autoclosing relay, installed on a medium voltage feeder. They are designed to trip when a fault is detected, then automatically reclose after a set amount of time in an attempt to clear transient faults on the feeder. They can save considerable time when restoring power.

Bus bar (busbar)

An electrically conductive bar connecting two or more electrical circuits.

CT - Current Transformer

Current Transformers are used to measure current for protection and measurement in switchgear applications.


Data Communication Equipment.


An insulating medium between conductors.

DNP3 - Distributed Network Protocol 3

DNP3 is a communications protocol used for SCADA communications.NOJA Power's range of OSM reclosers are supplied with the DNP3 protocol as standard.


Distribution System Automation.

ITS - Interface Test Set

The Interface Test Set simulates the current and voltage signals generated by sensors inside the OSM recloser bushings for system testing purposes. It is used to perform tests such as three phase short circuit, phase to phase short circuit, earth fault, upstream broken wire, low source voltage and loss of supply.

MCC - Motor Control Centre

A modular cabinet system for powering and controlling motors in a mine or factory.