Types of Faults

1. Single-Line-to-Ground Fault (SLG)

   • Description: Occurs when one phase conductor makes contact with the ground.
   • Characteristics:
     • Common in systems with high capacitance to ground.
     • Typically results in a lower fault current compared to other types of faults.
   • Impact: Can lead to equipment damage, nuisance tripping, and potential fire hazards.

2. Line-to-Line Fault (LL)

   • Description: Occurs when two phase conductors come into contact with each other.
   • Characteristics:
     • Fault current is generally higher than single-line-to-ground faults.
     • Can cause significant thermal and mechanical stress on equipment.
   • Impact: Affects the phases involved and can cause severe equipment damage if not cleared promptly.

3. Double-Line-to-Ground Fault (LLG)

   • Description: Occurs when two phase conductors each make contact with the ground.
   • Characteristics:
     • Fault current is usually higher than a single-line-to-ground fault but lower than a three-phase fault.
     • Causes significant voltage imbalance and can disrupt system operation.
   • Impact: Can lead to equipment damage and affect system stability.

4. Three-Phase Fault (LLL)

   • Description: Occurs when all three phase conductors come into contact with each other or with the ground.
   • Characteristics:
     • Produces the highest fault current, causing maximum thermal and mechanical stress on equipment.
     • Typically results in a balanced fault with equal current in all phases.
   • Impact: Can lead to severe equipment damage and system instability.

5. Three-Phase Fault with Ground (LLLG)

   • Description: Occurs when all three phases come into contact with the ground.
   • Characteristics:
     • Fault current is the highest among all fault types.
     • Causes significant disruption and damage to equipment.
   • Impact: Can lead to extensive damage and requires immediate protection and isolation.