where B is the total susceptance. If we assume Er to be the reference phasor, the current will
describe a circle as the angle δ of Es changes from 0 to 2π. If we further assume that the two
voltages are of equal magnitude (1.0 pu), the circle described by the current will pass through the
origin as shown in Figure 10.7. Now consider the voltages at the intermediate buses E1 and E2,
shown in Figure 10.6. E2 can be calculated from the voltage at the receiving bus: