Introduction to Electrical Engineering

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Pro: ČEKO IMPORT a.s.
Vydal: České vysoké učení technické Praha Autor: Vladimír Kůla, Michal Kříž

Strana 85 z 112

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In addition, the effective earthing resistance the system shall verified where necessary. that case the verification the continuity the protective conductors sufficient 2) verification the characteristics the associated protective device (i. .e. Where conditions, which are similar conditions systems, occur the event a second fault, verification made according point this clause. This measurement not necessary all exposed conductive parts the installation are connected the power system earth the case where the system connected earth through impedance. c) For systems Calculation measurement the first fault current.e. 2. Note: During the measurement the loop impedance, necessary establish connection negligible impedance between the neutral point the system and the protective conductor the origin the installation. The measurement made only the calculation not possible, because all the parameters are not known. Notes: 1. visual inspection the nominal current setting for circuit-breakers and the current rating for fuses and also test for residual current protective devices). current setting for circuit- breakers, current rating for fuses); - for the protective conductors inspection their continuity. This verification shall made: - for residual current devices visual inspection and test; - for overcurrent protective devices visual inspection (i. Measurement the resistance the earth electrode Measurement the resistance earth electrode, where prescribed, made an appropriate method. Where conditions similar conditions similar conditions systems occur, verification made according point this clause. Measurement fault loop impedance Measurement the loop impedance shall effected the same frequency the nominal frequency the circuit.VERIFICATION ELECTRICAL EQUIPMENT AND INSTALLATION 86 of the length and cross-sectional area the conductors. b) For systems Compliance with the rules for systems shall verified by: 1) measurement the resistance the earth electrode for exposed conductive parts the installation; 2) verification the characteristics the associated protective device. Precautions are taken while making this measurement order avoid the danger due double fault