How we can find the direction of angular displacement?

Answer 1

'Angular displacement' is the angle by which the secondary line-to-line voltage lags the primary line-to-line voltage. It can be directly measured by constructing a phasor-diagram for the primary and secondary line-voltages for a three-phase transformer.

Answer 2

The direction of angular displacement is determined by the right-hand rule: if you curl your fingers in the direction of rotation from the initial position to the final position, then your thumb points in the direction of the angular displacement. Clockwise rotations are generally considered negative, and counterclockwise rotations are positive.