Automatic testing of wired relay circuits

PRACTICALLY ALL of the telephone switching equipment in an automatic exchange is made up of wired assemblies of relays and other components interconnected by a multiplicity of wires. Many of these assemblies are made up of smaller components called “relay circuit units.” These vary in size, and after testing, are mounted in larger frameworks. A careful check of connections and electrical continuity is essential to assure that these units will function properly when connected to other circuits in a telephone exchange.