11.2.1 IdentificationFunction description IEC 61850identificationIEC 60617identificationANSI/IEEE C37.2device numberOverfrequency protection SAPTOFf >SYMBOL-O V1 EN8111.2.2 ApplicationOverfrequency protection function SAPTOF (81) is applicable in all situations, wherereliable detection of high fundamental power system frequency is needed. The powersystem frequency, and rate of change of frequency, is a measure of the unbalance betweenthe actual generation and the load demand. High fundamental frequency in a powersystem indicates that the available generation is too large compared to the powerdemanded by the load connected to the power grid. SAPTOF (81) detects such situationsand provides an output signal, suitable for generator shedding, HVDC-set-point changeand so on. SAPTOF (81) is very sensitive and accurate and can also be used to alertoperators that frequency has slightly deviated from the set-point, and that manual actionsmight be enough.11.2.3 Setting guidelinesAll the frequency and voltage magnitude conditions in the system where SAPTOF (81)performs its functions must be considered. The same also applies to the associatedequipment, its frequency and time characteristic.There are two application areas for SAPTOF (81):1. to protect equipment against damage due to high frequency, such as generators, andmotors2. to protect a power system, or a part of a power system, against breakdown, byshedding generation, in over production situations.The overfrequency pickup value is set in Hz. All voltage magnitude related settings aremade as a percentage of a settable global base voltage parameter VBase. The UBase valueshould be set as a primary phase-to-phase value.Some applications and related setting guidelines for the frequency level are given below:1MRK 506 369-UUS - Section 11Frequency protectionLine distance protection REL670 2.2 ANSI 595Application manual
