When the measured frequency returns to the level corresponding to the settingRestoreFreq, a 100ms pulse is given on the output RESTORE after a settable timedelay (tRestore).10.1.7.3 BlockingIt is possible to block underfrequency protection SAPTUF completely, by binaryinput signal:BLOCK: blocks all outputsIf the measured voltage level decreases below the setting of MinValFreqMeas in thepreprocessing function both the START and the TRIP outputs are blocked.10.1.7.4 DesignThe design of underfrequency protection SAPTUF is schematically described infigure 103.Figure 104: Simplified logic diagram for SAPTUF10.1.8 Technical dataTable 158:SAPTUF Technical dataFunction Range or value AccuracyOperate value, start function (35.00-75.00) Hz ± 2.0 mHz atsymmetrical three-phase voltageOperate value, restorefrequency(45 - 65) Hz ± 2.0 mHzReset ratio <1.001 -Operate time, start function At 50 Hz: 200 ms typically at fset +0.5 Hz to fset-0.5 HzAt 60 Hz: 170 ms typically at fset +0.5 Hz to fset-0.5 Hz-Reset time, start function At 50 Hz: 60 ms typically at fset -0.5 Hz to fset+0.5 HzAt 60 Hz: 50 ms typically at fset -0.5 Hz to fset+0.5 Hz-Operate time delay (0.000-60.000)s <250 msRestore time delay (0.000-60.000)s <150 ms10.2 Overfrequency protection SAPTOFSection 10 1MRK 504 135-UEN AFrequency protection234Technical manual
