op pMeasuredat k bI cIMaxAddDelay= × +-æ öç ÷ç ÷ç ÷æ öç ÷ç ÷ç ÷è øè øEQUATION1418 V1 EN-US (Equation 13)where:top is operate timek is time multiplier of the inverse time curvea, b, c, p are settings that will model the inverse time characteristic6.1.3.6 Settings examples M12541-349 v3M12941-3 v8Setting example with a power transformer in the protected zoneFigure 44 shows a line with a power transformer in the protected zone. Circuitimpedances are presented in Figure 45. The protected zone is limited by threecurrent transformers: CT1, CT2 and CT3. IEDs are situated in two separatesubstations 1 and 2.The circuit is protected by two terminals 1 and 2. These terminals process the samedata except for minor distortion in data that takes place during communicationbetween them. Both terminals operate as masters. If at least one of them indicatesan internal fault, the protected circuit is disconnected.IED 2Line 50 km CT 3Substation 2Substation 1Current samples from terminals 2 and 3Current samples from terminal 1CT 2Yd1200 MVA,220 / 70 kV,525 / 1650 AY d220 kV, 600 ACB 1terminal 2 terminal 3CB 2CB 3terminal 1 CT 1IED 1IEC05000534-2-en.vsdxIEC05000534 V2 EN-USFigure 44: Line differential protection with a power transformer in theprotected zone1MRK 505 393-UEN B Section 6Differential protectionLine differential protection RED650 2.2 IEC 97Application manual
