Short circuits and ground faults
A short-circuit fault is an abnormal, low-impedance connection between two or more conductors in contact with each other in an electrical device or circuit, causing current to flow through those contacting conductors bypassing the normal path. Short-circuit faults often result in a sudden increase in current, which can lead to serious consequences such as overloading, damage, or even fire on equipment or circuits.
A ground fault is when a conductor in an electrical device or circuit accidentally comes into contact with ground (usually the ground wire of the ground or the device), causing current to flow to the ground through the ground fault point. Ground faults can lead to problems such as electrified equipment housings, personal shock hazards, and equipment damage.
Short-circuit faults can be caused by:
Damage to wires or cables: Wires or cables may be physically damaged during use, such as crushing, cutting, abrasion, etc., resulting in direct short circuits between wires or between wires and equipment.
Aging or cracking of insulation: Insulation in electrical equipment or circuits can age, crack, or break down over time, causing insulation failures between wires or between wires and equipment, resulting in short circuits.
Equipment design or manufacturing defects: During the design or manufacturing of electrical equipment, there may be defects or errors, such as insufficient spacing between wires, weak insulation, etc., which make it easy to short-circuit faults.
Overload or sudden current change: When a circuit or device is subjected to currents that exceed its rated load, it can cause heat generation of wires, damage to insulation, and lead to short-circuit faults. In addition, sudden changes in current, such as arc flashovers, can also lead to short-circuit faults.
External factors: External factors such as disasters, animal exposure, bad weather, etc., can also cause short-circuit faults in circuits or equipment.
Human factors: Improper human operation, violation of safety regulations, and incorrect wiring are also common causes of short circuit failures.
Ground faults can be caused by:
Insulation Damage: Insulation materials in electrical equipment or circuits (e.g., insulating sleeves, insulation, etc.) are physically damaged, aged, or cracked, resulting in direct contact between the conductor and the earth.
Equipment installation error: During the installation of electrical equipment, ground failure may occur if the grounding wire is poorly connected, the grounding wire is disconnected, and the grounding wire is misconnected with other conductors.
Equipment design or manufacturing defects: In the design or manufacturing process of electrical equipment, there may be defects or errors, such as unreasonable design of the grounding wire, excessive grounding resistance, etc., resulting in the occurrence of grounding faults.
External factors: External factors such as lightning strikes, animal contact, fallen trees, etc., can also cause ground failures of equipment or circuits.
Geological problems in the underground power system: In the underground power system, geological factors such as underground structure and soil moisture can also lead to the occurrence of grounding faults.
Human factors: Improper human operation, negligence, and violation of safety regulations are also common causes of grounding failures.