Name Values (Range) Unit Step Default DescriptionOperDCBiasing OffOn- - Off Operation DC biasing On / OffOpenCTEnable OffOn- - Off Open CT detection feature Off/OntOCTAlarmDelay 0.100 - 10.000 s 0.001 1.000 Open CT: time to alarm if an open CT isdetected, in sectOCTResetDelay 0.100 - 10.000 s 0.001 0.250 Reset delay in s. After delay, diff.function is activatedtOCTUnrstDelay 0.100 - 100.000 s 0.001 10.000 Unrestrained diff. protection blockedafter this delay, in sTempIdMin 1.0 - 5.0 IdMin 0.1 2.0 Temp. Id pickup when inputraisePickUp=1, multiple of IdMinTable 32:GENPDIF Non group settings (basic)Name Values (Range) Unit Step Default DescriptionGlobalBaseSel 1 - 6 - 1 1 Selection of one of the Global BaseValue groups5.3.6 Operation principleThe task of Generator differential protection GENPDIF is to determine whether afault is within the protected zone, or outside the protected zone. The protected zoneis delimited by the position of current transformers, as shown in figure 47.xx06000430.vsdIEC06000430 V1 ENFigure 47: Position of current transformers; the recommended (default)orientationIf the fault is internal, the faulty generator must be quickly tripped, that is,disconnected from the network, the field breaker tripped and the power to theprime mover interrupted.GENPDIF function always uses reference (default) directions of CTs towards theprotected generator as shown in figure 47. Thus, it always measures the currents onthe two sides of the generator with the same reference direction towards thegenerator windings. With the orientation of CTs as in figure 47, the difference ofcurrents flowing in, and out, of a separate stator winding phase is simply obtainedby summation of the two currents fed to the differential protection function.Section 5 1MRK 502 034-UEN -Differential protection102Technical Manual
