If source impedance in the near and far end of the protected line have changed in asignificant manner relative to the set values at fault location calculation time (dueto exceptional switching state in the immediate network, power generation out oforder, and so on), new values can be entered via the local HMI and a recalculationof the distance to the fault can be ordered using the algorithm described below. It’salso possible to change fault loop. In this way, a more accurate location of the faultcan be achieved.The function indicates the distance to the fault as a percentage of the line length, inkilometers or miles according to the setting LineLengthUnit. The fault location isstored as a part of the disturbance report information (ER, DR, IND, TVR and FL)and managed via the local HMI or PCM600.14.9.7.1 Measuring Principle M14983-4 v2For transmission lines with voltage sources at both line ends, the effect of double-end infeed and additional fault resistance must be considered when calculating thedistance to the fault from the currents and voltages at one line end. If this is notdone, the accuracy of the calculated figure will vary with the load flow and theamount of additional fault resistance.The calculation algorithm used in the fault locator in compensates for the effect ofdouble-end infeed, additional fault resistance and load current.M14983-5 v114.9.7.2 Accurate algorithm for measurement of distance to fault M14983-7 v5Figure 318 shows a single-line diagram of a single transmission line, that is fedfrom both ends with source impedances ZA and ZB. Assume that the fault occurs ata distance F from IED A on a line with the length L and impedance ZL. The faultresistance is defined as RF. A single-line model is used for better clarification ofthe algorithm.Section 14 1MRK 506 382-UEN AMonitoring626 Line distance protection REL650 2.2 IECTechnical manual
