10.2.6.3 Blocking M14958-13 v7It is possible to block overfrequency protection SAPTOF partially or completely,by binary input signals or by parameter settings, where:BLOCK: blocks the START and TRIP outputsBLKTRIP: blocks the TRIP outputIf the measured voltage level decreases below the setting of IntBlockLevel, both theSTART and the TRIP outputs are blocked.10.2.6.4 Design M14958-24 v9The frequency measuring element continuously measures the frequency of thepositive sequence voltage and compares it to the setting StartFrequency. Thefrequency signal is filtered to avoid transients due to switchings and faults in thepower system. The time integrator operates due to a definite delay time. The designof overfrequency protection SAPTOF is schematically described in figure 130.Frequency f > StartFrequencyVoltage startTRIPU < IntBlockLevelblockBLOCKORDefinite timertResettDelayIEC16000042-1-en.vsdxtripSTARTBLKDMAGNBLKTRIPANDStart&TripoutputlogicIEC16000042 V1 EN-USFigure 130: Simplified logic diagram for SAPTOFSection 10 1MRK 505 394-UEN AFrequency protection276 Line differential protection RED650 2.2 IECTechnical manual
