preprocessing function, which is discussed in the Basic IED Functions chapter and isset as a percentage of a global base voltage parameter VBase, SAPTOF (81) is blocked,and the output BLKDMAGN is issued. All voltage settings are made in percent of theglobal parameter VBase. To avoid oscillations of the output PICKUP signal, ahysteresis has been included.10.2.7.2 Time delayThe time delay for SAPTOF (81) is a settable definite time delay, specified by thesetting tDelay.If the PICKUP condition frequency ceases during the delay time, and is not fulfilledagain within a defined reset time, the PICKUP output is reset.10.2.7.3 BlockingIt is possible to block Over frequency protection (SAPTOF, 81) 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 Signal Matrix for analog inputs (SMAI), both the PICKUP andthe TRIP outputs, are blocked.10.2.7.4 DesignThe design of overfrequency protection SAPTOF (81) is schematically described infigure 138.1MRK 502 043-UUS B Section 10Frequency protection297Technical Manual
