To provide an effective protection for the generator for external unbalanced conditions,NS2PTOC (46I2) is able to directly measure the negative sequence current. NS2PTOC(46I2) also has a time delay characteristic which matches the heating characteristic ofthe generator 22I t K= as defined in standard IEEE C50.13.where:I2 is negative sequence current expressed in per unit of the ratedgenerator currentt is operating time in secondsK is a constant which depends of the generators size and designNS2PTOC (46I2) has a wide range of K settings and the sensitivity and capability ofdetecting and tripping for negative sequence currents down to the continuous capabilityof a generator.A separate output is available as an alarm feature to warn the operator of a potentiallydangerous situation.8.9.3 Function blockANSI08000359-2-en.vsdNS2PTOC (46I2)I3P*BLOCKBLK1BLK2TRIPTRST1TRST2PICKUPPU_ST1PU_ST2ALARMNSCURRANSI08000359 V2 ENFigure 109: NS2PTOC (46I2) function block8.9.4 SignalsTable 124:NS2PTOC (46I2) Input signalsName Type Default DescriptionI3P GROUPSIGNAL- Group connection for neg seq.BLOCK BOOLEAN 0 Block of functionBLK1 BOOLEAN 0 Block of step 1BLK2 BOOLEAN 0 Block of step 2Section 8 1MRK 502 043-UUS BCurrent protection238Technical Manual
