Vector Diagram of Practical (Real) Transformer on Load By : Dr. Atul R. Phadke Associate Professor in Electrical Engineering Government College of Engineering, Karad (Maharashtra) PHASOR DIAGRAM OF TRANSFORMER (INDUCTIVE LOAD): I1 π 1 π1 Iw V1 π 0 πΌ2′ I0 N1 π 2 N2 π2 I2 V1 Iµ π0 I1X1 I1Z1 I1 I1R1 E1 E2 V2 ZL -E1 πΌ2′ ο¦1 I0 Iw Magnetizing component of no load current πΌπ is in phase with flux ο¦. Iµ Working component of no load current πΌπ€ is leading to πΌπ by 900. No load current πΌ0 = πΌπ€ + πΌπ Induced emfs πΈ1 and πΈ2 are lagging behind the flux by 900. When transformer is loaded, current πΌ2 flows in secondary. As the load is inductive, current πΌ2 lags behind πΈ2 . Thus, load component of primary current πΌ2′ = πΎ × πΌ2 flows in primary. ο¦ ο¦2 I2 V2 E1 -I2X2 -I2Z2 -I2R2 E2 Primary current πΌ1 = πΌ0 + πΌ2′ π1 = πΈ1 + πΌ1 (π 1 + ππ1 ) = πΈ1 + πΌ1 π1 Angle between π1 and πΌ1 is ∅1 . π2 = πΈ2 − πΌ2 (π 2 + ππ2 ) = πΈ2 − πΌ2 π2 Angle between π2 and πΌ2 is ∅2 . 2 PHASOR DIAGRAM OF TRANSFORMER (CAPACITIVE LOAD): I1 π 1 π1 Iw V1 π 0 πΌ2′ I0 N1 π 2 N2 π2 I1Z1 I1X1 I2 V1 I1R1 Iµ π0 -E1 E1 E2 V2 ZL I1 πΌ2′ ο¦1 I0 No load current πΌ0 = πΌπ€ + πΌπ Induced emfs πΈ1 and πΈ2 are lagging behind the flux by 900. ο¦2 When transformer is loaded, current πΌ2 flows in secondary. As the load is capacitive, current πΌ2 leads to πΈ2 . I2 E1 Thus, load component of primary current πΌ2′ = πΎ × πΌ2 flows in primary. -I2R2 Primary current πΌ1 = πΌ0 + πΌ2′ V2 π1 = πΈ1 + πΌ1 (π 1 + ππ1 ) = πΈ1 + πΌ1 π1 -I2X2 Angle between π1 and πΌ1 is ∅1 . ο¦ E2 -I2Z2 π2 = πΈ2 − πΌ2 (π 2 + ππ2 ) = πΈ2 − πΌ2 π2 Angle between π2 and πΌ2 is ∅2 . 3
