Identify Fault Condition

In a single line-to-ground (SLG) fault, the symmetrical component theory states that the phase current is the sum of its positive, negative, and zero sequence components.

$I_f = I_{a1} + I_{a2} + I_{a0}$

Apply Sequence Component Relationship

For an SLG fault, the sequence currents are equal: $I_{a1} = I_{a2} = I_{a0}$. Therefore, the total fault current is three times the zero sequence current.

$I_f = 3 I_{a0}$

Calculate Zero Sequence Current

Given $I_f = 100$ A, we rearrange the formula to find $I_{a0}$.

$I_{a0} = \frac{100}{3} \approx 33.33 \text{ A}$