Question

With the American Standard notation, in either a $\mathbf{Y}\mathbf{-}\mathbf{\Delta }$ or$\mathbf{\Delta }\mathbf{-}\mathbf{Y}$ transformer, positive-sequence quantities on the high-voltage side shall lead their corresponding quantities on the low-voltage side by $\mathbf{30}\mathbf{°}$.

(a) True (b) False

Short answer

Therefore, the correct option is (a) True.

Step-by-step solution

Draw the phase shifting Y-Δ transformer.

The core arrangement for the phase shifting$\mathrm{Y}-\mathrm{\Delta }$ transformer.

Figure for the analysing the angle between the quantities.

Determine the phase shift between the high voltage side and low voltage side.

From the figure shown in step 1, it is clear that the voltage$V_{AN}\&V_{ab}$ are in the same phase and $V_{an}$is lag by$30°$ with respect to $V_{ab}$. Therefore, the phase shift between the voltage$V_{AN}\&V_{an}$ is$-30°$ .

Hence,positive-sequence quantities on the high-voltage side shall lead their corresponding quantities on the low-voltage side by $30°$.