Basic AC Power POWER TRIANGLE Power in Series R-L Circuit Figure 4    Series R-L Circuit Example:   A 200 W resistor and a 50  W  X_L  are placed in series with a   voltage   source,   and   the   total current  flow  is  2  amps,  as  shown in Figure 4. Find:    1. pf 2. applied voltage, V 3. P 4. Q 5. S Solution: 1. pf cosq q arctan X_L R cos arctan X_L R cos arctan 50 200 cos  (14°) pf 0.097 2. V IZ Z R² X²_L I  R² X²_L 2 200² 50² 2 42,500 (2)(206.16) V 412.3  volts Note:   Inverse   trigonometric   functions   such   as   arctan   are   discussed   in   the   Mathematics Fundamentals Manual, Module 4, Trigonometry, pages 6 and 7 should the student require review. Rev. 0 Page 5 ES-09