Name Values (Range) Unit Step Default DescriptionRestoreFreq 45.00 - 65.00 Hz 0.01 49.90 Restore frequency valuetRestore 0.000 - 60.000 s 0.001 0.000 Restore time delaytReset 0.000 - 60.000 s 0.001 0.000 Time delay for resetTable 149:SAPFRC Non group settings (basic)Name Values (Range) Unit Step Default DescriptionGlobalBaseSel 1 - 12 - 1 1 Selection of one of the Global BaseValue groups10.3.6 Operation principle M14970-3 v9Rate-of-change frequency protection SAPFRC is used to detect fast power systemfrequency changes at an early stage. SAPFRC has a settable definite time delay. Ifthe rate-of-change of frequency remains below the set value, for negative rate-of-change, for a time period equal to the chosen time delay, the TRIP signal is issued.If the rate-of-change of frequency remains above the set value, for positive rate-of-change, for a time period equal to the chosen time delay, the TRIP signal is issued.To avoid an unwanted trip due to uncertain frequency measurement at low voltagemagnitude a voltage controlled blocking of the function is available, that is, if thevoltage is lower than the set blocking voltage IntBlockLevel the function is blockedand no START or TRIP signal is issued. If the frequency recovers, after afrequency decrease, a restore signal is issued.10.3.6.1 Measurement principle M14970-6 v8The rate-of-change of the fundamental frequency of the selected voltage ismeasured continuously, and compared with the set value, StartFreqGrad. Rate-of-change frequency protection SAPFRC is also dependent on the voltage magnitude.If the voltage magnitude decreases below the setting IntBlockLevel, SAPFRC isblocked, and the output BLKDMAGN is issued. The sign of the settingStartFreqGrad, controls if SAPFRC reacts on a positive or on a negative change infrequency. If SAPFRC is used for decreasing frequency that is, the settingStartFreqGrad has been given a negative value, and a trip signal has been issued,then a 100 ms pulse is issued on the RESTORE output, when the frequencyrecovers to a value higher than the setting RestoreFreq. A positive setting ofStartFreqGrad, sets SAPFRC to START and TRIP for frequency increases.To avoid oscillations of the output START signal, a hysteresis has been included.10.3.6.2 Time delay M14970-10 v7Rate-of-change frequency protection SAPFRC has a settable definite time delay,tDelay.1MRK 505 394-UEN A Section 10Frequency protectionLine differential protection RED650 2.2 IEC 279Technical manual
