The voltage regulation of the transformer will be negative when the power factor angle (φ) is :
1
\(\varphi>\tan ^{-1}\left(\frac{R}{X}\right)\)
2
\(\varphi=\tan ^{-1}\left(\frac{R}{X}\right)\)
3
\(\varphi<\tan ^{-1}\left(\frac{R}{X}\right)\)
4
φ > 0