The generator shown in Figure 3-1 has a differential protection as the one shown in class. It is known that for an external three-phase (balanced) fault the fault current on

the primary side has a magnitude of 5 kA. Due to saturation of the current transformers, the secondary currents for this external fault are the ones shown in Figure 3-2. a. You are asked to demonstrate that the relay settings used in class (s=0.25 and Ipu=0.5 A) are not appropriate. Show, algebraically and graphically that the relay operates for the condition shown in the figure. b. The relay used here has a fixed Ipu at 0.5 A. The slope setting can be chosen as one of the following values: 0.1, 0.2, 0.25, 0.3, 0.4 and 0.5. Assuming that the CTs are also fixed, determine the value of the slope setting to assure the relay will not operate for the external fault shown in figure. С.Plot your solution and graphically show that the new relay setting is appropriate.