Cables, whether used for power transmission or communication, are the lifelines of modern infrastructure. Cables are susceptible to faults that can disrupt services and require timely diagnosis and repair. Understanding the common types of cable faults is crucial for engineers, technicians, and maintenance personnel involved in cable management. Let's explore the common types of cable faults.
Open circuit fault: If the cable insulation is normal, but a type of fault that cannot transmit voltage normally due to conductors, it can be considered as an open circuit fault, such as the core wire or ground wire seems to be broken and broken, and there is a large wire resistance and disconnection in a certain part of the core wire, etc. Generally, simple open circuit faults are rarely seen, and most of them coexist with low-resistance or high-resistance faults.
Low-resistance fault: If the insulating medium of the cable is damaged, a type of phase-to-phase or phase-to-ground fault that can be directly tested by the "low-voltage pulse method" is called a leakage low-resistance fault. Often called a low-resistance fault. The general resistance value is below several hundred ohms. If the resistance value is "zero", it is called a short-circuit fault, which is a special case of a low-resistance fault.
Leakage high-resistance fault: If the insulating medium of the cable is damaged and a fixed resistance channel is formed, but a type of fault that cannot be directly measured by the "low-voltage pulse method" of the cable fault flash detection instrument is called a leaky high-resistance fault. The resistance value is usually above hundreds of ohms. When the DC leakage withstand voltage test is performed on the cable in the field, the leakage current value increases continuously with the increase of the applied DC voltage, and far exceeds the standard value required by the cable itself. Leakage high-resistance faults are relative to low-resistance faults, and there is no strict distinction.
Flashover high resistance fault: within the pre-test voltage range of the cable, when the pre-test voltage of the cable is added to a certain value, the leakage current value of the cable suddenly increases, and its value greatly exceeds the specification value required by the tested cable. This type of fault is called a flashover high-resistance fault. At this fault point, although the cable insulation is damaged, it does not form a fixed resistance channel.