GB346932A - Improvements in or relating to automatic or semi-automatic telephone systems - Google Patents

Abstract

346,932. Automatic exchange systems. COVENTRY AUTOMATIC TELEPHONES, Ltd., MOSS, B. F. and HOCKNEY, T. R., of General Electric Co., Stoke, Coventry. March 8, 1930, No. 7603. [Class 40 (iv).] Test-final-selectors or similar switches, e.g. trunk offering final selectors are available for use either by a test clerk for normal service or by an automatic or semi-automatic routiner. As shown, connections 1-20 represent a multiple jack which normally is disconnected so that a clerk via a test distributer (not shown) and connections 22 .. 28 has access to a selector, Fig. 1, and by known methods may step the selector to and test any subscriber's line appearing in the selector bank. When it is required to operate the selector by a routiner (partly shown in Fig. 2) a plug is inserted in the jack to complete the connections. Line 27 is thereby busied to prevent the test distributer seizing the selector and upon operation of key A, vertical stepping magnet V and relay VV are operated. When the selector steps, relay VG is looked energized. Upon release of key A, V and VV are released and rotary magnet R is operated to step selector in the first level. Magnet R releases VG which de-energizes R after which testing proceeds automatically in known manner. At the successful completion of a test, magnet R is again operated over routiner lead 33 and testing of the next line in the level takes place, the operations being repeated until the selector reaches the end of the level and cam springs S1, S2, S3 are operated. Relay ZZ now operates to energize rotary release magnet RZ and relay VZ. The selector is thus released for rotary motion and relay VZ operates vertical magnet V and relay VV, to step the selector to the second level and energize relay VG to close the circuit of R and initiate the test cycle in the second level of bank contacts. The test is repeated in a similar manner until when the end of the last level is reached contacts NP1 operate relay VC to terminate movement. A supervisory lamp SL then glows to indicate that all lines available have been tested. Instead of test-final selectors, trunk offering switches may be modified in a similar manner to make them available for use either by trunk offering operators or by the routiner.