Faults

A fault in an electric power system denotes any abnormal condition leading to the electrical failure of equipment, such as transformers, generators, busbars, and other components.

Fixing Faults on 330 kV Transmission Lines

Faults in an electrical power system are categorized into Open circuit and Short circuit faults. Short circuit faults are further categorised into:

1. Symmetrical faults: These faults affect all phases equally, keeping the system balanced. For instance, a three-phase fault.
2. Unsymmetrical faults: These cause unequal currents and phase shifts in a three-phase system. Examples include line-to-ground, line-to-line, and two-line-to-ground faults.

Faults Classification in Electrical Power System

Faults can also be categorized based on their type:

1. Permanent
2. Transient

Or classified by the participating Phases as:

1. 1-ph, 2-ph or 3-ph
2. Phase-Earth
3. Phase-Phase
4. Phase-Phase-Earth
5. Three-Phase or Three-Phase-Earth

Different Faults on electricity Lines (Phases)

Causes of Faults

Several factors contribute to faults in an electrical power system:

1. Equipment Failures: Malfunctions in electrical equipment such as generators, motors, transformers, reactors, and switching devices can lead to short circuit faults, often caused by insulation failures in cables and windings.




Equipment failure





2. Aging: The aging process of power equipment can result in insulation breakdown, even under normal power frequency voltage conditions.




Aging Equipment





3. External Causes: Objects like birds, kites, or tree branches can cause faults by spanning one conductor and ground (leading to a single line to ground fault) or spanning two conductors (resulting in a phase-phase fault).




Fault due to External Causes




4. Weather Conditions: Environmental factors such as lightning strikes, heavy rains, strong winds, salt deposits on overhead lines, and the accumulation of snow and ice on transmission lines can disrupt power supply and damage electrical installations.




Weather Condition





5. Human Errors: Mistakes by humans, such as selecting equipment with improper ratings, leaving conductive parts behind after maintenance, or switching circuits during servicing, can cause electrical faults.




Human Error: Food Delivery Drone on Electricity Line





6. Smoke from Fires: The ionization of air due to smoke particles around overhead lines can lead to sparks between lines or between conductors and insulators. This flashover can diminish the insulating capacity of insulators under high voltage conditions.




Smoke from Fires on Transmission Equipment

Impacts of Faults

A few of the impacts of faults are listed below:

1. Overcurrent Flow: When a fault occurs, it creates a low impedance path, resulting in a very high current drawn from the supply. This can trip relays, damage insulation, and harm the components of the equipment.




Over Current




2. Danger to Operating Personnel: Faults can cause electric shocks to individuals, with the severity depending on the current and voltage at the fault location. In extreme cases, it can be fatal.




Personnel Falling off the ladder while fixing Faults




3. Loss of Equipment: Short circuit faults cause heavy currents that can burn components completely, leading to malfunctioning equipment. Severe fires may result in complete equipment burnout.




Heavy Current due to Short Circuit fault on Equipment




4. Disturbance to Interconnected Circuits: Faults not only affect the fault location but also disrupt active interconnected circuits, causing parts of the system to operate as unbalanced three-phase systems. This can lead to improper equipment operation and abnormal system voltages, potentially damaging equipment.




Disturbance to Interconnected Circuits Resulting in Frequency Oscillation





5. Electrical Fires: Short circuits can cause flashovers and sparks due to the ionization of air between two conducting paths. This can lead to fires, as often reported in buildings and shopping complexes.




Electrical Fire Caused by Short circuits