Analyze the relationship between sequence currents

In an unbalanced fault analysis using symmetrical components, the relationship between sequence currents identifies the fault type. Here, we check the sum of sequence currents: $I_{sum} = I_{positive} + I_{negative} + I_{zero}$.

$I_{sum} = j1.753 - j0.6 - j1.153$

Calculate the sum

Adding the given values: $I_{sum} = j(1.753 - 0.6 - 1.153) = j(0) = 0$.

$I_{sum} = 0$

Determine fault type based on conditions

Since $I_{positive} + I_{negative} + I_{zero} = 0$, this is a condition for a line-to-line fault. However, if any sequence current is non-zero and they are not equal, it indicates a double line-to-ground (LLG) fault. Specifically, in LLG faults, all three sequence networks are connected in parallel. Since all three are non-zero and their sum is zero, it represents a Line-to-Line-to-Ground fault.

$I_1 + I_2 + I_0 = 0 \text{ and } I_0 \neq 0$