Basic AC Theory AC GENERATION ANALYSISExample 2: The peak current in an AC circuit is 10 amps. What is the average value ofcurrent in the circuit?Iav = 0.637 ImaxIav = 0.637 (10 amps)Iav = 6.37 ampsPhaseAnglePhase angle is the fraction of a cycle, in degrees, that has gone by since a voltage or current haspassed through a given value. The given value is normally zero. Referring back to Figure 3,take point 1 as the starting point or zero phase. The phase at Point 2 is 30°, Point 3 is 60°, Point4 is 90°, and so on, until Point 13 where the phase is 360°, or zero. A term more commonlyused is phase difference. The phase difference can be used to describe two different voltages thathave the same frequency, which pass through zero values in the same direction at different times.In Figure 5, the angles along the axis indicate the phases of voltages e1 and e2 at any point intime. At 120°, e1passes through the zero value, which is 60° ahead of e2(e2equals zero at180°). The voltage e1 is said to lead e2 by 60 electrical degrees, or it can be said that e2 lags e1by 60 electrical degrees.Figure 5 Phase RelationshipRev. 0 Page 7 ES-07
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