Section 7 Impedance protection7.1 Underimpedance protection for generators andtransformers ZGCPDIS (21G)7.1.1 IdentificationFunction description IEC 61850identificationIEC 60617identificationANSI/IEEE C37.2device numberUnderimpedance protection forgenerators and transformersZGCPDIS 21G7.1.2 FunctionalityThe underimpedance protection for generators and transformers ZGCPDIS(21G), hasthe offset mho characteristic as a three zone back-up protection for detection of phase-to-phase short circuits in transformers and generators. The three zones haveindependent measuring and settings that gives high flexibility for all types of applications.A load encroachment characteristic is available for the third zone as shown in figure57.1MRK 502 043-UUS B Section 7Impedance protection133Technical Manual
