(a) Single-phase-to earth.(b) Phase-to-phase.(c) All the three phases-to earth.(d) Two phases-to earth.Answer: (c) All the three phases-to earth.Explanation: 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.
(a) Single-phase-to earth.
(b) Phase-to-phase.
(c) All the three phases-to earth.
(d) Two phases-to earth.
Answer: (c) All the three phases-to earth.
Explanation:
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 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.