Process and apparatus for locating faults on a line through the use of travelling wave signals

Claim 1

A process for locating faults on a line, wherein at least one signal (travelling-wave signal) associated with a travelling wave on the line and corresponding to the temporal progression thereof at the measuring location is formed from the voltage and current at the measuring location, the improvement comprising the steps of: forming pairs of oppositely moving travelling-wave signals corresponding in number to the phases or conductors in the line and decoupled from one another in relation to the line inductances and line capacitances, forming at least two time-integrals with these travelling-wave signals or signals derived therefrom as integrands, each time-integral being associated with one direction of wave-propagation on the line, and processing these time-integrals by an evaluating function to produce a value which characterizes by way of at least any one of its sign and magnitude the direction and distance, respectively, of the fault with respect to a predetermined reference location on the line, which evaluating function corresponds to a relationship prevailing at the fault location between the travelling waves moving in opposite directions on the line.

Claim 22

An apparatus for locating faults on a line with respect to a predetermined reference location, comprising: a. a voltage- and current-measuring circuit provided at a measuring location on the line, the voltage- and current measuring circuit having outputs carrying voltage-current signal pairs (u m , i m ) corresponding in number to the phase or conductors in the line and independent of one another with respect to the line inductances and line capacitances; b. a multiplication circuit connected to the voltage- and current-measuring circuit, said multiplication circuit serving for the multiplication of at least one of the independent current signals (i m ) by a factor (R w ) corresponding to a characteristic impedance associated with the relevant current signal; c. a summation circuit having an input side and an output side, said input side being connected to said measuring circuit and to the multiplication circuit, said summation circuit serving for the formation of at least two travelling-wave signals in the form of a = u m + R w ·i m and b = -u m + R w ·i m with u m and i m as the voltage-current signal pair and R w as the factor corresponding to an associated characteristic impedance; d. travelling-wave signal channels connected with the output side of said summation circuit; e. a modification circuit incorporated into the travelling-wave signal channels for the purpose of generating a mutual variation in the temporal progression of the travelling-wave signals associated with a reference location on the line; f. a integrating circuit for forming time-integrals of the travelling-wave signals and incorporating an integration-interval switching device; and e. an evaluating circuit connected to ouputs of the integrating circuit, inputs of said evaluating circuit being fed with time-integrals formed from travelling-wave signals proceeding in opposite directions to one another or signals derived from these time-integrals.

Claim 23

An apparatus for locating faults on a line with respect to a predetermined reference location, comprising: a. a voltage- and current-measuring circuit provided at a measuring location on the line, the voltage- and current measuring circuit having outputs carrying voltage-current signal pairs (u m , i m ) corresponding in number to the phase or conductors in the line and independent of one another with respect to the line inductances and line capacitances; b. a multiplication circuit connected to the voltage- and current-measuring circuit, said multiplication circuit serving for the multiplication of at least one of the independent current signals (i m ) by a factor (R w ) corresponding to a characteristic impedance associated with the relevant current signal; c. a summation circuit having an input side and an output side, said input side being connected to said measuring circuit and to the multiplication circuit, said summation circuit serving for the formation of at least two travelling-wave signals in the form of a = u m + R w ·i m and b = -u m + R w ·i m with u m and i m as the voltage-current signal pair and R w as the factor corresponding to an associated characteristic impedance; d. travelling-wave signal channels connected with the output side of said summation circuit; e. a modification circuit incorporated into the travelling-wave signal channels for the purpose of generating a mutual variation in the temporal progression of the travelling-wave signals associated with a reference location on the line; f. a integrating circuit for forming time-integrals of the travelling-wave signals and incorporating an integration-interval switching device; and e. an evaluating circuit connected to ouputs of the integrating circuit, inputs of said evaluating circuit being fed with time-integrals formed from travelling-wave signals proceeding in opposite directions to one another or signals derived from these time-integrals.