2025-09-16
A cable fault tester is a comprehensive cable fault detection instrument and an essential tool for maintaining various cables. It can detect high-resistance flashover faults, high- and low-resistance ground faults, short circuits, cable breaks, and poor contact. Equipped with an acoustic locator, it can accurately determine the fault location. It is particularly suitable for testing power cables and communication cables of various models and voltage levels.
Let's analyze the types of cable faults detected by a cable fault tester:
1. Open Circuit Fault: A fault in which the cable insulation is normal but the conductor cannot transmit voltage properly is considered an open circuit fault. Examples include a core wire or ground wire that appears to be broken, high resistance at a certain point in the core wire, and a core break. Simple open circuit faults are rare and often manifest as coexisting low-resistance or high-resistance faults.
2. Low-Resistance Fault: A phase-to-phase or phase-to-ground fault that can be directly detected using the "low-voltage pulse method" is called a leakage low-resistance fault. These faults are typically less than a few hundred ohms. If the resistance value is "zero," it's called a short-circuit fault, a special case of a low-resistance fault.
3. Leakage High-Resistance Fault: When the cable's insulation is damaged, a fixed resistance path is formed, but this type of fault cannot be directly measured using the "low-voltage pulse method" of a cable fault tester. This is called a leakage high-resistance fault. The resistance is typically above several hundred ohms. When performing a DC leakage withstand voltage test on a cable in the field, the leakage current increases continuously with increasing DC voltage, far exceeding the cable's specified value. Leakage high-resistance faults and low-resistance faults are relative and not strictly distinguished.
4. Flashover High-Resistance Fault: Within the cable's pretest voltage range, when the pretest voltage reaches a certain value, the cable's leakage current suddenly increases, significantly exceeding the specified value for the tested cable. This type of fault is called a flashover high-resistance fault. At this fault point, although the cable insulation is damaged, no fixed resistance path is formed.
