Table 127:NS2PTOC (46I2) Non group settings (basic)Name Values (Range) Unit Step Default DescriptionGlobalBaseSel 1 - 6 - 1 1 Selection of one of the Global Base Valuegroups8.9.6 Monitored dataTable 128:NS2PTOC (46I2) Monitored dataName Type Values (Range) Unit DescriptionNSCURR REAL - A Negative sequence current inprimary amps8.9.7 Operation principleThe negative sequence time overcurrent protection for machines (NS2PTOC, 46I2)function directly measures the amplitude of the negative phase sequence component ofthe measured current. NS2PTOC (46I2) sets the PICKUP, PU_ST1 or PU_ST2 outputsactive and starts to count trip time only when the measured negative sequence currentvalue rises above the set value of parameters I2-1> or I2-2> respectively.To avoid oscillation in the output signals, a certain hysteresis has been included. Forboth steps, the reset ratio is 0.97.Step 1 of NS2PTOC (46I2) can operate in the Definite Time (DT) or Inverse Time(IDMT) mode depending on the selected value for the CurveType1 parameter. IfCurveType1= Definite, NS2PTOC (46I2) operates with a Definite Time Delaycharacteristic and if CurveType1 = Inverse, NS2PTOC (46I2) operates with an InverseTime Delay characteristic. Step 2 can only operate in the Definite Time (DT) mode.The characteristic defines the time period between the moment when measurednegative sequence current exceeds the set pickup levels in parameter I2-1> or I2-2>until the trip signal is initiated.Definite time delay is not dependent on the magnitude of measured negative sequencecurrent. Once the measured negative sequence current exceeds the set level, thesettable definite timer t1 or t2 respectively, starts to count and the corresponding tripsignal gets activated after the pre-set definite time delay has elapsed. Reset time indefinite time mode is determined by the setting parameters tResetDef1 or tResetDef2respectively. If NS2PTOC (46I2) has already picked up but not tripped and measurednegative sequence current goes below the pickup value, the pickup outputs remainsactive for the time defined by the resetting parameters.A BLOCK input signal resets NS2PTOC (46I2) momentarily.Section 8 1MRK 502 043-UUS BCurrent protection240Technical Manual
