7.8.9.4 Simplified logic diagramUinjRshuntROTIPHIZREX060REG6701IUu_i_refu_u_refXSK1K2Compare &EvaluateZRef1ZRef2324567IEC10000327-2-en.vsdBareZMeasuredZInjIInjU¸RfIEC10000327 V1 ENFigure 129: Simplified logic diagram for sensitive rotor earth fault protection,injection based ROTIPHIZ1 The sensitive rotor earth fault protection function receives amplified injected voltage andcurrent via the REX060 unit as two voltages signals. (Voltage inputs in the IED)2 The phasor of injected voltage UInj and phasor of injected current IInj is calculated by usingspecial filter from raw samples. Observe that phasors are calculated for the injectedfrequency.3 The complex bare impedance is calculated from Uinj / Iinj.4, 5 The complex measured impedance is derived as ZMeasured = Zbare*k1 +k2 [Ω].6 The fault resistance (Rf) is calculated from the complex measured impedance and a selectedcomplex reference.7 Selection of one (out of maximum 2) ZRef.Section 7 1MRK502052-UEN BImpedance protection290Technical manual
