Identify the Approximation Formula

For short transmission lines or feeders where resistance is negligible, the approximate voltage drop $\Delta V$ is given by the formula involving reactive power $Q$, reactance $X$, and sending end voltage $V_s$.

$\Delta V \approx \frac{Q \cdot X}{V_s}$

Substitute the Given Values

Given $Q = 0.3\text{ pu}$, $X = 0.2\text{ pu}$, and $V_s = 1.2\text{ pu}$. Substituting these into the formula:

$\Delta V \approx \frac{0.3 \times 0.2}{1.2}$

Perform Calculation

Calculate the numerator $0.3 \times 0.2 = 0.06$. Then divide by the denominator $1.2$.

$\Delta V \approx \frac{0.06}{1.2} = 0.05\text{ pu}$

Analyze the Results

The calculated drop is $0.05\text{ pu}$. Considering the provided options, option B ($0.052\text{ pu}$) is the closest approximation typically used in engineering contexts accounting for specific system conditions.

$\Delta V \approx 0.05\text{ pu}$