Circuit arrangement for determining the reactance of a power transmission line in the event of a short circuit

A circuit arrangement for determining the reactance of a power transmission line in the event of a short circuit comprising:

• (a) means for coupling to said circuit arrangement a first measurement variable derived from the short circuit current in the power transmission line and a second measurement variable derived from the short circuit voltage on the power transmission line;
• (b) a phase shifter having said first measurement variables as an input and providing at its output an auxiliary measurement variable which leads its input approximately by a phase angle corresponding to the phase difference between the current and voltage in the case of a metallic short circuit;
• (c) first and second switches, coupled to be actuated in the event of a short circuit having as inputs the second and the auxiliary measurement values respectively for forming an output variable;
• (d) means, having inputs coupled to said switches, for forming an output variable proportional to the phase angle between the first and second measurement variables;
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• (e) means for storing the maximum value of the second measurement variable and the auxiliary measurement variable coupled to the outputs of said switches;
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• (f) computing means having as inputs the output of said means for storing the maximum value and the output of said means for forming.