Improvements in or relating to subscriber's line circuits

Improvements in or relating to subscriber's line circuits

836,225. Automatic exchange systems. AUTOMATIC TELEPHONE & ELECTRIC CO. Ltd. Jan. 16, 1958 [Feb. 28, 1957], No. 6660/57. Class 40 (4). In a system in which battery is permanently connected by resistors R1, R2 over the subscriber's loop (e.g. for testing for the calling condition of the subs...

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Bibliographische Detailangaben
Hauptverfasser: DENBY JAMES FREDERICK, ALLUM ROBIN DEVENISH
Format: Patent
Sprache:eng
Schlagworte:
ELECTRIC COMMUNICATION TECHNIQUE
ELECTRICITY
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Zusammenfassung:836,225. Automatic exchange systems. AUTOMATIC TELEPHONE & ELECTRIC CO. Ltd. Jan. 16, 1958 [Feb. 28, 1957], No. 6660/57. Class 40 (4). In a system in which battery is permanently connected by resistors R1, R2 over the subscriber's loop (e.g. for testing for the calling condition of the subscriber as described in Specification 766,563) potentials which are equal but opposite with respect to earth are applied to opposite legs. This enables the insulation resistance RA, RB of each leg to be tested by a low resistance meter M connected between that leg and battery of the same voltage and dolarity as that permanently connected to the leg, without the latter effecting the reading.