percent of the global parameter UBase. To avoid oscillations of the output STARTsignal, a hysteresis has been included.START STARTTRIPStart&TripOutputLogicDefinite Time DelayTimeDlyOperateBLOCKIEC09000033-1.vsdFrequency Comparatorf > StartFrequencyTRIPBLKDMAGNBLOCKORfreqNotValidIEC09000033 V1 ENFigure 152: Schematic design of overfrequency protection SAPTOF10.2.7.2 Time delayThe time delay for SAPTOF is a settable definite time delay, specified by the settingtDelay.If the START condition frequency ceases during the delay time, and is not fulfilledagain within a defined reset time, the START output is reset.10.2.7.3 BlockingIt is possible to block Over frequency protection (SAPTOF) completely, by binaryinput signals or by parameter settings, where: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.10.2.7.4 DesignThe design of overfrequency protection SAPTOF is schematically described infigure 152.1MRK 502 048-UEN A Section 10Frequency protection301Technical manual
