Patent ID: 6288553
Filing Date: 2001-09-11
Classification: G01R

Abstract:
A method for determining a loop resistance of a power supply network having a neutral conductor (N), an external conductor (L1), a protective earth conductor (PE), and a fault current circuit breaker (FI) for breaking the L1 and N conductors based on a magnitude of a current in the PE conductor, comprising the following steps:connecting a load resistance R.sub.load between the L1 conductor and the N conductor thereby loading a network loop L1-N; anddetermining a phase resistance R.sub.L 1 of the external conductor (L1) according to the equation,R.sub.L1 =R.sub.load.cndot.(.DELTA.U.sub.LN -.DELTA.U.sub.N)/U.sub.LNwherein.DELTA.U.sub.LN =a magnitude of a voltage differential between a first voltage between L1 and N with the load resistance present and a second voltage between L1 and N without the load resistance present;U.sub.LN =a network voltage between L1 and N when the load resistance is present;.DELTA.U.sub.N =a voltage differential between the N and PE conductors;applying a measuring current I.sub.M to a network loop comprising the L1 and PE conductors, wherein said measuring current is small enough to avoid triggering the fault current circuit breaker, anddetermining a phase resistance R.sub.PE of the protective earth conductor (PE) according to the equation:R.sub.PE =U.sub.PE /I.sub.Mwherein U.sub.PE is a voltage drop between the N and PE conductors anddetermining a loop resistance of an L1-PE loop as the sum of an internal resistance of the L1 conductor R.sub.L1, and the phase resistance R.sub.PE.