Method of detecting the changes over time in the electrical properties of an at least two-wire line, means for implementing this method and installations comprising at least one conducting line equipped with these means

摘要

The invention relates to a method of detecting the changes over time in the electrical properties of an at least two-wire electrically conducting line. It is characterised in that: - on the end of the line opposite that bearing the end-of-line component 42, the line 1 is linked to an oscillating circuit 2 which, for normal conditions of operation of the assembly formed by the line 1 and its end-of-line component 42, sends out a signal 8 at a defined frequency and with a duty cycle which is also defined, - this signal 8 is picked up and addressed to a bistable circuit 18 which is preadjusted so that, throughout the time for which the signal with predetermined frequency and duty cycle is addressed to it, this circuit 18 is held in a so-called equilibrium position, while for any alteration of at least one of these predetermined values. Application to the industry of electrical surveillance equipment. IMAGE