11.1.6 Monitored dataTable 202:SDDRFUF Monitored dataName Type Values (Range) Unit Description3I0 REAL - A Magnitude of zerosequence current3I2 REAL - A Magnitude of negativesequence current3U0 REAL - kV Magnitude of zerosequence voltage3U2 REAL - kV Magnitude of negativesequence voltage11.1.7 Operation principle11.1.7.1 Zero and negative sequence detectionThe zero and negative sequence function continuously measures the currents andvoltages in all three phases and calculates: (see figure 157)• the zero-sequence voltage 3U0• the zero-sequence current 3I0• the negative sequence current 3I2• the negative sequence voltage 3U2The measured signals are compared with their respective set values 3U0< and 3I0>,3U2< and 3I2>.The function enable the internal signal FuseFailDetZeroSeq if the measured zero-sequence voltage is higher than the set value 3U0> and the measured zero-sequencecurrent is below the set value 3I0<.The function enable the internal signal FuseFailDetNegSeq if the measured negativesequence voltage is higher than the set value 3U2> and the measured negativesequence current is below the set value 3I2<.A drop off delay of 100 ms for the measured zero-sequence and negative sequencecurrent will prevent a false fuse failure detection at un-equal breaker opening at thetwo line ends.Section 11 1MRK 502 048-UEN ASecondary system supervision310Technical manual
