Monitoring system for multiwire telephone cable connections - employs optical detectors selected by gates to provide audible and visible alarms for differentiating between damp and faulty wires

摘要

The system monitors the connections and particularly the insulation problems due to humidity in multiwire telephone cables. A fault monitoring cabinet is located in a telephone exchange and monitors a number of cables via OR gate selectors controlled from a control unit. The selector outputs are applied to detectors comprising comparators which drive photocouplers. Lamps signal prescence of humidity in partic. cables while an audible alarm signal, that one of the cables is faulty. The photocoupler outputs are gated (54) through monostables to enable a NAND gate in oscillator circuits to drive a loudspeaker. A digital display unit identifies the number of a connection.