April 8, 2012

Fault Current in Electrical Power System

The fault current that occurs in electrical power system is usually large and dangerous. Fault current is 10 to 20 times more than normal rating. Faults may be short circuits or partial short circuits, open circuits, unbalanced conditions, or any circumstances. 

Sometimes, the occurrence of fault cannot be avoided due to human error, aging factor, external interference, natural disaster and etc.

The principal types of fault are:-

Faults can damage or disrupt power system in several ways:
  • Large fault currents will cause overheating of power system components.
  • The extremely high temperature in arcs due to short circuits will causing equipment destruction and fire.
  • The system voltages can be lowered or raised outside their acceptable ranges.
  • Three phase system can become unbalanced thus causing three phase equipment to operate improperly.
  • Fault block the flow of power.
  • Fault can cause the system to become unstable and break-up (i.e lose synchronism)

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