Electrical Engineering ⇒ Topic : Approximate Voltage Drop in a Transformer

APPROXIMATE VOLTAGE DROP IN A TRANSFORMER

During no-load condition, V₁ is approximately equal to E_l and 0V₂ = E₂ where 0V₂ indicates no-load terminal voltage of the secondary. 0V₂ is also equal to E₁/a, i.e., equal to Vita. When secondary is loaded, let the secondary terminal voltage be V₂. The difference between V₂ and 0V₂ is the voltage drop across equivalent impedance in secondary, i.e., /₂Z_e2 shown in Figure (a).

                   Figure (a) Phasor diagram of a transformer referred to secondary

In Figure (a), R_e2 and X_e2 are the equivalent resistance and reactance, respectively referred tosecondary side. With 0 as centre, an arc is drawn in Figure (a) which intersects the extended OA at H. From C, a perpendicular is drawn on OH which interests it at G. Now, AC = AH represents the actual drop and AG represents the approximate voltage drop. BF is drawn perpendicular to OH from B. BE is drawn parallel to AG. The approximate voltage drop is written as

                                                                                                      ................. (1)

                                             ................. (2)

                                              ................. (3)