Causes of faults in a power system.

The faults in a power system can be caused by a wide range of causes.  Below is a list of some of the most probable causes for electrical faults.

Overvoltage is caused due to surges such as lightning or due to switching loads on and off.  In generators, it can be caused due to the failure of the field controller.

Heavy winds which can cause lines to snap or trees to fall on them. This can cause open circuits, earth faults and short circuits.

Ageing which can result in weakening of insulation and failure. This can result in short circuits and earth faults.

Chemical pollution and deposition on the insulators that can result in flash overs

Faults due to wildlife, such as birds, snakes, mice, etc which can cause short circuits and earth faults.

Collision of vehicles on towers and transmission poles can cause the towers to fall.

The table below will give an idea of the percentage of the types of faults in the different equipment in a power system

Overhead lines                      50%
Transformers                         12%
Switch gear                            15%
Cables                                   10%
Miscellaneous                         8%
Instrument Transformers        2%
Control Equipment                 3%