GB954225A - Improvements in or relating to security arrangements for electrical systems - Google Patents

Abstract

954,225. Automatic exchange systems. H.M. POSTMASTER GENERAL, STANDARD TELEPHONES & CABLES Ltd., GENERAL ELECTRIC CO. Ltd., AUTOMATIC TELEPHONE & ELECTRIC CO. Ltd., ASSOCIATED ELECTRICAL INDUSTRIES Ltd., and ERICSSON TELEPHONES Ltd. Nov. 1, 1961 [Nov. 7, 1960], No. 38168/60. Heading H4K. [Also in Division G1] In a set of interconnected interdependent electrical functional units in which a fault in one unit may affect the operation of another, fault finding is effected by automatically replacing units by like units in a predetermined sequence and automatically applying tests after each replacement. The invention may be applied to automatic telephone or telegraph exchange systems, or to computer and data processing systems generally. As shown, equipments A, B, C are interconnected in such manner that signals may pass both ways between A and B and between B and C and one way from A to C. Each equipment is provided with respective routine test equipments RA, RB, RC, under control of a fault analyser FA. When a routiner reports a fault, FA resets all the routiners and initiates a systematic replacement of such of the units A, B, C as could be responsible for the fault report, and in an order determined by fault reported. Thus suppose RA reports a fault which could be due to the malfunction of A or B. Then FA initiates replacement of unit A and the routiner RA is restarted. If the fault is no longer reported then unit A is indicated as faulty and the operation stopped. If, however, the fault still shows up then the routiners are reset, unit B is replaced, and a further routine test is conducted. Detailed circuitry for the equipment FA is provided, Fig. 2 (not shown), wherein different sequences are provided according to the nature of the reported fault. In a second embodiment, the equipments and their replacements are switched in, in all possible combinations, and an analysis of the fault reports made to indicate which units are faulty, and also to select a trouble-free combination for operational use. As shown. Fig. 3, a transmission path may pass either through equipment WA or SA and either through equipment WB or SB. Thus the control equipment, Fig. 4 (not shown), opens gates TG1 or TG3 and TG2 or TG4 in successive combinations for each of which a routine test is carried out and the result staticized. At the end of the cycle the staticized results are fed to gate combinations to indicate the faulty units, and used to enable appropriate ones of the gates TG1 . . . TG4 to provide an operational path. Specifications 940,016 and 954,226 are referred to.