Table 144:SAPTOF Non group settings (basic)Name Values (Range) Unit Step Default DescriptionGlobalBaseSel 1 - 12 - 1 1 Selection of one of the Global BaseValue groups10.2.6 Operation principle M14958-3 v7Overfrequency protection SAPTOF is used to detect high power system frequency.SAPTOF has a settable definite time delay. If the frequency remains above the setvalue for a time period corresponding to the chosen time delay, the correspondingTRIP signal is issued. To avoid an unwanted TRIP due to uncertain frequencymeasurement at low voltage magnitude, a voltage controlled blocking of thefunction is available, that is, if the voltage is lower than the set blocking voltageIntBlockLevel, the function is blocked and no START or TRIP signal is issued.10.2.6.1 Measurement principle M14958-6 v9The fundamental frequency of the positive sequence voltage is measuredcontinuously, and compared with the set value, StartFrequency. Overfrequencyprotection SAPTOF is dependent on the voltage magnitude. If the voltagemagnitude decreases below the setting IntBlockLevel, SAPTOF is blocked and theoutput BLKDMAGN is issued. All voltage settings are made in percent of theUBase, which should be set as a phase-phase voltage in kV. To avoid oscillations ofthe output START signal, a hysteresis has been included.10.2.6.2 Time delay M14958-9 v8The time delay for Overfrequency protection SAPTOF is a settable definite timedelay, specified by the setting tDelay.TRIP signal issuing requires that the overfrequency condition continues for at leastthe user set time delay, tDelay. If the START condition, with respect to themeasured frequency ceases during this user set delay time, and is not fulfilled againwithin a user defined reset time, tReset, the START output is reset, after that thedefined reset time has elapsed. It is to be noted that after leaving the hysteresisarea, the START condition must be fulfilled again and it is not sufficient for thesignal to only return back to the hysteresis area.The total time delay consists of the set value for time delay plusminimum operate time of the start function (80 - 90 ms).1MRK 505 394-UEN A Section 10Frequency protectionLine differential protection RED650 2.2 IEC 275Technical manual
