. Automatic telephony; a comprehensive treatise on automatic and semi-automatic systems . der slightly differ-ent conditions from other selectors, because the connectors are notlimited to sections of ten. As many as 27 connectors have been mountedon one lines witch-board, all their banks being common. Since there are TRUNKING, ITS PHYSICAL ARRANGEMENTS AND VARIATIONS 141 many five digit exchanges, it has become common to speak of theseselectors as third selectors, although in smaller and in larger exchangesthey are not thirds. Fourteen connectors may receive traffic from selectors as shown inF
. Automatic telephony; a comprehensive treatise on automatic and semi-automatic systems . der slightly differ-ent conditions from other selectors, because the connectors are notlimited to sections of ten. As many as 27 connectors have been mountedon one lines witch-board, all their banks being common. Since there are TRUNKING, ITS PHYSICAL ARRANGEMENTS AND VARIATIONS 141 many five digit exchanges, it has become common to speak of theseselectors as third selectors, although in smaller and in larger exchangesthey are not thirds. Fourteen connectors may receive traffic from selectors as shown inFig. 136. Eight sections of selectors scatter their traffic over the wholenumber, except that connector No. 14 is not yet installed. Connectors1 and 2 are for toll service, although they may be used for local calls aswell. They are called combined toll and local connectors. Thetoll third selectors reach only them. When seized by a toll selector,the combination connector gives the proper conditions for toll service. High Say A GLow doy — \ Selsctor Banks (One Level Only)B H „ ., C I. Fig 134.—Selector trunking (one level). Sections grouped by 3s and 6s. But when seized by a local selector, it acts like other (regular) connectors. The first eight contacts on the selector banks are slipped. The lasttwo are straight. The tenth contact alone leads to the toll connectors,so that a toll connector will not be taken for local service until all thelocal connectors are busy. Figure 137 shows how the terminals are arranged to secure this scatter-ing. The letters at the right indicate the bank cable from the sections,A and G being on the same supports, B and H on another set, etc. Ten of the connectors are brought onto the top terminal strip of theA-G support. This is all that would be necessary if there were only ten. 142 A U TOM A TIC TELEPUON Y The extra connectors are cared for by having an extra pair of terminalstrips above the A-G assembly, and by inserting an extra strip between
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttelephone, bookyear19
