Voltage Regulation of Transformer

The voltage regulation of a transformer is the arithmetic difference between the no load secondary voltage and voltage at load condition. Voltage in a transformer on load varies mainly due to its leakage reactance.

In other words, the change in the secondary terminal voltage from no-load to full-load condition is termed as voltage regulation.

For Unity Power Factor (or) Resistive Load

Take V₂' as reference. I₁ is in phase with V₂'

From vector diagram 1.41

For Lagging Power Factor or Inductive Load

From Figure 1.42.

i. Take V₂' as reference, I₁ lags V₂' by φ

ii. Draw I₁ R₀₁ parallel to I₁

iii. Draw I₁ X₀₁ (BC) perpendicular to AB

iv. Connect C and A, which is impedance drop I₁ Z₀₁

v. Join C and O. This gives secondary voltage at no load condition

For Leading Power Factor (or) Capacitive Load

From Figure 1.43

i. Take V₂' as reference, I₁ leads V₂' by φ

ii. Draw AB parallel to I₁

iii. Draw BC perpendicular to AB

iv. Join AC which is impedance drop I₁ Z₀₁

v. Join OC which gives V₁