Question

Which of the following faults results into a symmetrical fault?
1. Single phase to Earth
2. Two-phases to earth
3. Phase to Phase
4. All Three-phases to earth

Answer 1

Correct Answer - Option 4 : All Three-phases to earth

Symmetrical faults:

• A symmetrical fault is a fault where all phases are affected so that the system remains balanced
• A three-phase fault is a symmetrical fault
• As symmetrical faults result in balanced conditions, they may be analyzed using per-phase analysis
• LLLG fault is symmetrical fault

 

Unsymmetrical Faults:

• Unsymmetrical faults are the faults that lead unequal currents with unequal phase shifts in a three-phase system
• The unsymmetrical fault occurs in a system due to the presence of an open circuit or short circuit of transmission or distribution line
• It can occur either by natural disturbances or by manual errors
• The natural disturbances are heavy wind speed, ice loading on the lines, lightning strikes and other natural disasters.
• LG, LL, LLG faults are asymmetrical faults.