Final answer:
To indicate transformer phasing, dots on a transformer's symbol are aligned according to their phase relationship shown in phasor diagrams. In phase connections have aligned dots, and out of phase connections show dots with an angular offset. Phasor diagrams are used for visualizing these relationships.
Step-by-step explanation:
Transformer Phasing and Phasor Diagrams
To indicate the phasing of a transformer, dots are placed on the transformer's symbol.
The placement of these dots corresponds to the phasor diagrams that graphically represent phase relationships between current and voltage.
When transformers are in phase, the dots on corresponding sides are aligned, and the phases of the electrical signals match. In phasor diagrams, like in Figure 15.6(a), current is typically on the vertical axis, with the phasor representing it rotating.
The phasor diagram shows that some quantities, such as the current iR(t) and voltage UR(t), may be in phase, depicted by their phasors pointing in the same direction.
Furthermore, items that are out of phase, such as the voltage across an inductor (UL(t)) and a capacitor (Uc(t)), will have phasors that lead or lag each other by π/2 rad.
This concept is applied in Figure 15.12, indicating the phasing relationship in an AC circuit.
In terms of phasor representation in a phasor diagram, points that are in phase will have phasors that coincide or align precisely.
Points that are out of phase will display phasors that are offset from each other by a certain angle, usually π rad (180 degrees) for completely out of phase.
The length of one complete cycle on a phasor diagram represents one wavelength.