Method and apparatus for locating a fault on a line by means of travelling wave signals

An arrangement for locating a fault on a line with respect to a measuring location in which there is formed from the voltage and current at the measuring location at least one signal (travelling-wave signal) associated with a travelling wave on the line and its variation with time at the measuring location, comprising the combination of:

• a. a voltage and current measuring circuit having output means and provided at the measuring location on the line, the output means providing a number, corresponding to the phases or conductors of the line, of pairs of voltage-current signals (u.sub.m, i.sub.m) independent of one another in relation to the line inductance and line capacitance;
• b. a multiplication circuit connected with the voltage and current measuring circuit, said multiplication circuit serving to multiply at least one of the independent current signals (i.sub.m) by a factor R.sub.w) that corresponds to a characteristic impedance associated with the respective current signal;
• c. a summing circuit connected with the measuring circuit and the multiplication circuit, said summing circuit forming at least two oppositely moving travelling-wave signals of the form a = u.sub.m + R.sub.w .multidot.i.sub.m and b = -u.sub.m + R.sub.w .multidot.i.sub.m with u.sub.m and i.sub.m as a voltage-current signal pair and R.sub.w as a factor corresponding to an associated characteristic impedance;
• d. an integrating circuit for the formation of time integrals of the travelling-wave signals, said integrating circuit being provided with an intergration-interval switching device;
• e. an evaluation circuit connected with an output side of the integrating circuit, said evaluation circuit having inputs to which there are applied time integrals formed from mutually oppositely moving travelling-wave signals or signals derived from these time integrals.