8.4.2.8 Tapped line application SEMOD154453-265 v2SEMOD154453-267 v4CBBCIEC09000160-3-en.vsdAIEC09000160 V3 EN-USFigure 128: Example of tapped line with Auto transformerThis application gives rise to similar problem that was highlighted in section "Faultinfeed from remote end", that is, increased measured impedance due to faultcurrent infeed. For example, for faults between the T point and B station themeasured impedance at A and C will beA CA AT TFAI IZ Z ZI+= + ×EQUATION2302 V1 EN-US (Equation 166)2A CC Trf CT TFCI I U2Z Z Z ZI U1+= + + × ×æ ö æ öç ÷ç ÷ è øè øIECEQUATION1750 V1 EN-US (Equation 167)whereZAT and ZCT is the line impedance from the A respective C station to the T point.IA and IC is fault current from A respective C station for fault between T and B.U2/U1 Transformation ratio for transformation of impedance at U1 side of the transformer tothe measuring side U2 (it is assumed that current and voltage distance function istaken from U2 side of the transformer).Section 8 1MRK 506 369-UEN BImpedance protection248 Line distance protection REL670 2.2 IECApplication manual
