Improvements in or relating to security arrangements for electrical systems

Abstract

Abstract 954,226. 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. 38169/60. Heading H4K. [Also in Division G4] In a system for automatically detecting and replacing faulty functional units during a test period in which the units are idle, a continuous switching programme is carried out in which during first successive intervals ES1, ES2, ES3, Fig. 3, operational units E1, E2, E3 are replaced in turn by a spare unit ES, and in the following interval ES4, the spare unit is removed from channels IP1, OP1; IP2, OP2 and IP3, OP3, a test routine being applied by routiner RT. The switching is effected by means of gates EG1- EG3, ISG1-ISG3 and OSG1-OSG3. During each interval ES1-ES3 the units E1-E3 are connected in turn at instants t 1 , t 2 , t 3 with a checking circuit CHC through gates CG1-CG3, circuit CHC giving an output A if a fault is detected. Output A is used to stop the switching programme and cut out the faulty unit. Interval pulses ES1-ES3 are obtained from a counter CC1-CC4, Fig. 4, which is stepped on by pulses T. The arrangement of gates is such that on the occurrence of output A, pulses T are blocked at G1 and the counter is reset to the condition in which the trigger CC1-CC4 corresponding to the faulty unit is set. In another embodiment, Figs. 1, 2 (not shown) each unit E1-E3, ES has an individual checking circuit. Unit ES has an additional connection from IP1 through a gate which is opened at ES4 and its output, besides being connected to OP1-OP3 and its checking circuit through gates OSG1- OSG3, is also connected through a gate opened at ES4 to its checking circuit. In this way ES is continually tested by its checking circuit even during the intervals ES4 in which it is not conected in channels IP1, OP1-IP3, OP3.

Inventors

• 👤 Lionel Roy Frank Harris
• 👤 Charles Alan Maynard May
• 👤 Ronald George Knight
• 👤 David Gerald Bryan
• 👤 Edward Arthur Richard Peddle
• 👤 Robin Devenish Allum
• 👤 Brian Desmond Simmons
• 👤 Alfred Dargie Martin

Bibliographic Details