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Examoogle • User • info@examoogle.com • EE-2024-8821
Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
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When a line to ground fault occurs, the current in a faulted phase is 100 A. The zero sequence current in this case will be
Zero
33.3 A
66.6 A
100 A
33.3 A
Given: Fault current in a faulted phase (If) = 100 A for a line-to-ground fault.
Fault current in a faulted phase (If) = 100 A for a line-to-ground fault.
I0=31(Ia+Ib+Ic)
Identify the Symmetrical Component Relation
For a single line-to-ground (LG) fault, the sequence components are equal in magnitude and phase: I0=I1=I2. The total fault current If is equal to the sum of these three components.
If=I0+I1+I2=3I0
Relate Total Fault Current to Zero Sequence Current
Since the sequence currents are equal in a line-to-ground fault, the fault current is three times the zero sequence current.
I0=3If
Calculate the Result
Substitute the given fault current of 100 A into the derived formula.
I0=3100=33.33 A
B is correct because in a line-to-ground fault, the zero sequence current is exactly one-third of the total fault current in the faulted phase.
Remember that for line-to-line faults, the positive and negative sequence currents are equal and opposite, which is a common follow-up question in GATE/ESE exams.