High current electrical junction selector for three=phase supply - has groups of three adjacent insulated tongues on cursor which slides on scale to separate normally closed contacts in junction sockets

摘要

The secondaries of three current transformers corresponding to each of the three phases are connected to four conductors for connecting to measuring instruments by the normally closed elastic contacts. The scale (30) is butted at each end to retain the cursors (31,32) and it has marks to identify each group of three electrical junctions. Each cursor has the tongues (33,34,35) on its lower external surface and an upper plate (38) which both covers the mark not preselected and has an embossing underneath to lodge in a hole (39) on the scale. The scale is of width to accommodate three such cursors for selecting say 500,200 and 100A. ADVANTAGE - Avoids errors in positioning tongues which might lead to instrument damage.