Method and apparatus for determining the existence of a defect in an electrical line and its location

Claim 3

A surveillance device for determining defects and their locations in a plurality of electrical lines defining a plurality of phase-ground and phase-phase loops in a multiphase distribution system, a defect in a loop of said liNes being defined by its resistance Rd and its distance x from a measuring point, the values thereof being within a closed surveillance contour plotted in a plane with reference to coordinates system x and Rd, and determined by the characteristics of said lines and said multiphase distribution system, comprising : a. input means which comprise : I. analog means for producing signals representative of the currents and voltages in said lines and signals representative of the inherent voltage drop per unit length in each of said lines; II. selective switching means for sequentially selecting the representative signals concerning every phase-phase or phase-ground loop; and b. computing means which comprise : I. means for computing, on the basis of said representative signals concerning the loop selected by the selective switching means, the value of the resistance Rd of a possible defect in the concerned loop; II. first comparator means for comparing the computed value of Rd with two predetermined values bounding in the plane, a surface including the closed surveillance contour; III. means responsive to said first comparator means for operating said selective switching means to select the following loop when the computed value of Rd is outside of a range bounded by said predetermined values; IV. means responsive to said first comparator means for computing the value of the distance x of the possible defect in the concerned loop on the basis of said representative signals selected by the selective switching means; V. second comparator means for comparing the pair of computed values of x and Rd with pairs of predetermined values to locate in the plane the pair of computed value of x and Rd with reference to the closed surveillance contour; VI. means responsive to said second comparator means for operating said selective switching means to select the following loop when the pair of computed values of x and Rd are outside said closed surveillance contour; VII. intervention means responsive to said second comparator means for disconnecting the lines forming the concerned loop when the pair of computed values of x and Rd are inside said closed surveillance contour.

Claim 4

A surveillance device for determining defects and their locations in a plurality of electrical lines defining a plurality of phase-ground and phase-phase loops in a multiphase distribution system, a defect in a loop of said liNes being defined by its resistance Rd and its distance x from a measuring point, the values thereof being within a closed surveillance contour plotted in a plane with reference to coordinates system x and Rd, and determined by the characteristics of said lines and said multiphase distribution system, comprising : a. input means which comprise : I. analog means for producing signals representative of the currents and voltages in said lines and signals representative of the inherent voltage drop per unit length in each of said lines; II. selective switching means for sequentially selecting the representative signals concerning every phase-phase or phase-ground loop; and b. computing means which comprise : I. means for computing, on the basis of said representative signals concerning the loop selected by the selective switching means, the value of the resistance Rd of a possible defect in the concerned loop; II. first comparator means for comparing the computed value of Rd with two predetermined values bounding in the plane, a surface including the closed surveillance contour; III. means responsive to said first comparator means for operating said selective switching means to select the following loop when the computed value of Rd is outside of a range bounded by said predetermined values; IV. means responsive to said first comparator means for computing the value of the distance x of the possible defect in the concerned loop on the basis of said representative signals selected by the selective switching means; V. second comparator means for comparing the pair of computed values of x and Rd with pairs of predetermined values to locate in the plane the pair of computed value of x and Rd with reference to the closed surveillance contour; VI. means responsive to said second comparator means for operating said selective switching means to select the following loop when the pair of computed values of x and Rd are outside said closed surveillance contour; VII. intervention means responsive to said second comparator means for disconnecting the lines forming the concerned loop when the pair of computed values of x and Rd are inside said closed surveillance contour.

Claim 5

The surveillance device of claim 2 wherein said input means further comprise: a. a plurality of analog voltage detectors and a plurality of analog current detectors associated with said electrical lines; b. a plurality of analog circuits connected to said analog current detectors for producing a signal representative of the inherent voltage drop per unit length in each of said electrical lines; c. a multiple switch closed for an extremely brief and perfectly synchronized time; d. a plurality of analog memories each connected by means of said multiple switch to a voltage detector, a current detector or an analog circuit; e. at least two groups of principal digital memories; f. double switches; g. analog digital converters each being connected by means of said double switches to at least one of said analog memories and to at least one of said principal digital memories, the double switches connected to principal digital memories belonging to a group being actuated simultaneously, the double switches connected to principal digital memories belonging to two distinct groups being actuated at two distinct moments; h. at least two groups of auxiliary digital memories coupled by said selecting switch means to said principal digital memories, said groups of auxiliary digital memories corresponding to the group of said principal digital memories, stocking representative signals concerning the loop selected by said selective switching means and being further connected to said computing means.

Claim 6

The surveillance device of claim 3, further comprising subtractor circuit means coupled between auxiliary memOry and two principal digital memories.

Claim 7

The surveillance device of claim 2, wherein said intervention means comprises: a. a plurality of binary memories each corresponding to a phase-ground or phase-phase loop determined by said electrical lines and to a zone relative to a section of these lines as determined by said surveillance contour, each of said memories being activated in response to the detection of a defect in the zone and in the loop to which it corresponds, b. triggering order circuits coupled to said binary memories and activated in response to said binary memory which corresponds to a first zone and to a defect between two zones, and also through delay circuits to the binary memory which corresponds to a defect between two phases and in other zones.

Claim 8

The surveillance device as claimed in claim 5, wherein said delay circuits comprise logic gates and a binary counter, the capacity of said binary counter being a function of the delay which is to be introduced.