8-8 G60 GENERATOR PROTECTION SYSTEM – INSTRUCTION MANUALSETTINGS CHAPTER 8: APPLICATION OF SETTINGS8Since this element coordinates with system protections, a timed reset is chosen. The element must be blocked for a VT fusefailure. The neutral source is chosen. Make the following changes in the EnerVista software or the front panel SETTINGS GROUPED ELEMENTS SETTING GROUP 1 PHASE CURRENT PHASE TOC1 menu.8.2.9 Backup distanceThis function provides time-delayed protection for system faults that have not been cleared by system protections andprovides backup protection for stator faults.The “Line” source is used in this example to permit the application of a forward and reverse zone. The memory duration isto be left at the default setting (10 cycles).Zone 1 looks forward and covers the generator step-up (GSU) transformer and the transmission line leaving the station.Zone 3 looks in the reverse direction and covers the stator winding. Zone 2 is not used in this example. Both the VTs and theCTs are located on the low voltage side of the GSU transformer. The sample transformer diagram (first figure in thischapter) shows this transformer to be Yd1. Consequently, due to the location of instrument transformers, Dy11 is chosenfor both the XFMR VOL CONNECTION and XFMR CUR CONNECTION settings. There are no transformers in the reverse direction.Therefore “None” is chosen for both of the zone 3 transformer connection settings. Set the reach of the zone 1 element at120% of impedance of the GSU transformer and the transmission line. In the instance that there are multiple lines and/ormultiple generators, the zone 1 reach must be increased to compensate for the infeed effect.Eq. 8-25Eq. 8-26Eq. 8-27
