There are two specific application areas for SAPTUF:1. to protect equipment against damage due to low frequency, such as generators,transformers, and motors. Overexcitation is also related to low frequency2. to protect a power system, or a part of a power system, against breakdown, byshedding load, in generation deficit situations.The under frequency start value is set in Hz. All voltage magnitude related settingsare made as a percentage of a global base voltage parameter. The UBase valueshould be set as a primary phase-to-phase value.Some applications and related setting guidelines for the frequency level are givenbelow:Equipment protection, such as for motors and generatorsThe setting has to be well below the lowest occurring "normal" frequency and wellabove the lowest acceptable frequency for the equipment.Power system protection, by load sheddingThe setting has to be below the lowest occurring "normal" frequency and wellabove the lowest acceptable frequency for power stations, or sensitive loads. Thesetting level, the number of levels and the distance between two levels (in timeand/or in frequency) depends very much on the characteristics of the power systemunder consideration. The size of the "largest loss of production" compared to "thesize of the power system" is a critical parameter. In large systems, the loadshedding can be set at a fairly high frequency level, and the time delay is normallynot critical. In smaller systems the frequency start level has to be set at a lowervalue, and the time delay must be rather short.The voltage related time delay is used for load shedding. The settings of SAPTUFcould be the same all over the power system. The load shedding is then performedfirstly in areas with low voltage magnitude, which normally are the mostproblematic areas, where the load shedding also is most efficient.10.2 Overfrequency protection SAPTOF IP15747-1 v310.2.1 IdentificationM14866-1 v4Function description IEC 61850identificationIEC 60617identificationANSI/IEEE C37.2device numberOverfrequency protection SAPTOFf >SYMBOL-O V1 EN-US81Section 10 1MRK 511 401-UEN AFrequency protection246 Bay control REC670 2.2 IECApplication manual
