7.6.8 Technical dataTable 113:OOSPPAM technical dataFunction Range or value AccuracyImpedance reach (0.00 - 1000.00)% of Zbase ±2.0% of Ur/(√3 ⋅ Ir)Rotor start angle (90.0 - 130.0) degrees ±5.0 degreesRotor trip angle (15.0 - 90.0) degrees ±5.0 degreesZone 1 and Zone 2 trip counters (1 - 20) -7.7 Loss of excitation LEXPDIS7.7.1 IdentificationFunction description IEC 61850identificationIEC 60617identificationANSI/IEEE C37.2device numberLoss of excitation LEXPDIS<SYMBOL-MM V1 EN407.7.2 FunctionalityThere are limits for the under-excited operation of a synchronous machine. Areduction of the excitation current weakens the coupling between the rotor and thestator. The machine may lose the synchronism and start to operate like an inductionmachine. Then, the reactive power consumption will increase. Even if the machinedoes not loose synchronism it may not be acceptable to operate in this state for a longtime. Reduction of excitation increases the generation of heat in the end region of thesynchronous machine. The local heating may damage the insulation of the statorwinding and the iron core.To prevent damages to the generator it should be tripped when excitation is lost.Section 7 1MRK502052-UEN BImpedance protection272Technical manual
