Process for producing signals identifying faulty loops in polyphase electrical power supply

PCT No. PCT/DE96/02281 Sec. 371 Date Nov. 13, 1998 Sec. 102(e) Date Nov. 13, 1998 PCT Filed Nov. 22, 1996 PCT Pub. No. WO97/20219 PCT Pub. Date Jun. 5, 1997A method for producing signals indicating faulty loops in a polyphase electrical power supply network using impedance excitation, in which, after checking for ground faults, by comparing the amounts of the impedance values obtained during the impedance excitation, the signals indicating the faulty loops are formed. In order to eliminate with great certainty all the loops that are actually not faulty, in spite of initial excitation, in ascertaining loops which are exclusively free of ground faults, the actually faulty loops are determined by comparing calculated, virtual impedances, to impedances measured during the impedance excitation; in ascertaining at least one loop having ground faults, fault-free phase-to-ground loops are recognized and eliminated by comparing the amounts of the virtual impedance values, formed with respect to the phase-to-ground loops detected as faulty, to the smallest virtual impedance value, and fault-free phase-to-ground loops are recognized and eliminated. For further processing of the impedance values of the remaining loops ascertained as faulty and not eliminated, testing methods are used which are developed differently in light of the number of phase-to-ground loops determined simultaneously.