7.2.6 Monitored DataTable 81:SPTPIOC (50) Monitored dataName Type Values (Range) Unit DescriptionIA REAL - A Current in phase AIB REAL - A Current in phase BIC REAL - A Current in phase C7.2.7 Principle of operationThe sampled analog phase currents are pre-processed in a discrete Fourier filter (DFT)block. From the fundamental frequency components, as well as sampled values, of eachphase current the RMS value of each phase current is derived. These phase current valuesare fed to the Instantaneous phase overcurrent protection phase segregated outputSPTPIOC (50) function. In a comparator the RMS values are compared to the setoperation current value of the function Pickup. If a phase current is larger than the setoperation current a signal from the comparator for this phase is set to true. This signal will,without delay, activate the output signal TR_x(x=A, B or C) for this phase and the TRIPsignal that is common for all three phases.The SPTPIOC (50) function can be blocked from the binary input BLOCK.7.2.8 Technical dataTable 82:SPTPIOC (50) Technical dataFunction Range or value AccuracyOperate current (5-2500)% of lBase ± 1.0% of In at I £ In± 1.0% of I at I > InReset ratio > 95% -Operate time 20 ms typically at 0 to 2 x Iset -Reset time 30 ms typically at 2 to 0 x Iset -Critical impulse time 10 ms typically at 0 to 2 x Iset -Operate time 10 ms typically at 0 to 5 x Iset -Reset time 40 ms typically at 5 to 0 x Iset -Critical impulse time 2 ms typically at 0 to 5 x Iset -Dynamic overreach < 5% at t = 100 ms -1MRK 506 335-UUS A Section 7Current protection193Technical manual
