Automatic testing of wired relay circuits

PRACTICALLY all of the telephone switching equipment in an exchange is made up of wired assemblies - assemblies of relays and other components interconnected by a multiplicity of wires. These assemblies are on frameworks generally 11 feet 6 inches high. Many of these frameworks are made up of smaller components called relay circuit units composed mainly of relays. Rotary switches, resistors, capacitors, jacks, etc., necessary for the operation of switching circuits may also be included. These components vary in height up to about 24 inches and after testing they are mounted in the 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.