An electrical fault in a power system is actually an abnormal condition that is caused by equipment failures like transformers, human errors, and also environmental conditions.  These faults are very dangerous as it interrupts electrical flow and may damage your equipment and electrical appliances, and cause harm or death to humans and animals that come into contact.

Basically, there are two main types of electrical fault: Symmetrical and unsymmetrical.  Let’s briefly discuss the difference between the two.


Symmetrical faults are balanced faults, and occur when all the phases are short-circuited to one another simultaneously and often to the earth.  The system remains “symmetrical” in a way that the lines are displaced by an equal angle.  These are very severe faults but with rare occurrences.  Symmetrical faults have two types: (a) Three-phase short circuit fault (LLL), which is where three line of the conductor short with each other, but this, in fact, is a rare but the harshest kind of occurrence, and (b) Three-phase-to-ground fault (LLLG), which is a triple line-to-ground fault that occurs when three conductors fall on the ground or come in contact with the neutral conductor.


Unsymmetrical faults, on the other hand, are normal faults, which means three-phase lines become unbalanced. They are very common and less severe compared to symmetrical faults.  This occurs when there is the presence of a short circuit or open circuit of the transmission or distribution lines.  Unsymmetrical faults have these types: (a) Single line-to-ground fault (LG), where one conductor comes in contact with the ground terminal, (b) Line-to-line fault (LL), where two conductors are short circuited, and (c) Double line-to-ground fault (LLG), where two conductors fall on the ground or come into contact with the neutral conductor.

So, what causes these electrical faults to occur?

  1. Weather conditions – Lightning, heavy rains, strong winds, snow and ice accumulation can all lead to interruption of power supply and may even cause damage.
  2. Human errors – Yes, humans play a huge role in the success and failures of every electrical system.  Proper selection of equipment and devices are extremely important.  When doing maintenance work, the presence of mind of a highly trained electrician and plumber is also a must.  Switching current while servicing is a no-no.  Also, engineers need to make sure that all parts are intact and in good working condition.
  3. Failure on equipment – It is imperative to choose good quality equipment for electrical systems.  Transformers, motors, reactors, switching devices, generators, and the like malfunction or break and cause short circuits.

Electrical faults are not to be taken lightly. They may cause serious damage to devices and equipment that are connected to it, as voltages exceed beyond normal.  These could also cause electrocution to people or animals that come into contact with it.  In many cases, these also cause fire to buildings and homes, causing huge amounts of damage to property and may even take lives in the process.

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