In a three-phase system, an L-G fault is an example of which fault type?

• A. Symmetrical
• B. Asymmetrical
• C. Balanced
• D. None of the above

Answer: (B)

A line-to-ground fault creates an unbalanced condition in a three-phase system. When one line contacts the ground, fault current flows primarily in that single line, while the other two lines are affected through their electrical coupling. This makes the voltages and currents on the three phases no longer equal, so the fault is classified as asymmetrical. It isn’t a symmetrical (balanced) fault, which would involve all three phases behaving identically, and it isn’t a balanced condition because the system no longer shares currents and voltages evenly. For analysis, engineers often model such faults using positive, negative, and zero sequence networks to handle the introduced asymmetry.