Author: Noyafa–Cable Tester Manufacturer
Types and judgments of cable faults Whether it is a high-voltage cable or a low-voltage cable, faults are often formed due to short circuit, overload operation, insulation aging or external force in the construction equipment and operation process. Cable faults can be classified into three types and judgments of grounding, short-circuit and disconnection. Whether it is a high-voltage cable or a low-voltage cable, faults are often formed due to short-circuit, overload operation, insulation aging or external force in the construction equipment and operation process. . Cable faults can be classified into three categories: grounding, short circuit and disconnection. The types of faults mainly include the following aspects: one or two cores of a three-core cable are grounded.
Short circuit between two-phase cores. The three-phase cores are completely short-circuited. One-phase core wire is broken or multi-phase broken.
For direct short-circuit or disconnection faults, a multimeter can be directly measured and judged. For indirect short-circuit and ground faults, use a megohmmeter to measure the insulation resistance between core wires or the insulation resistance of core wires to ground, and determine the type of fault according to its resistance value. After the fault type is confirmed, it is not a simple task to find the fault point. Based on the author's experience, I will introduce several methods for finding the fault point for reference. Sound measurement method: The so-called sound measurement method is based on the sound of the faulty cable discharge. This method is more effective for the flashover discharge of the high-voltage cable core wire to the insulation layer. The equipment used in this method is a DC withstand voltage test machine.
The circuit wiring is shown in Figure 1, in which SYB is the high-voltage experimental transformer, C is the high-voltage capacitor, ZL is the high-voltage rectifier silicon stack, R is the current limiting resistor, Q is the discharge ball gap, and L is the cable core wire. When the capacitor C is charged to a certain voltage value, the ball gap discharges the faulty core wire of the cable, and the cable core wire discharges to the insulation layer at the faulty place."nourish, nourish"The sound of spark discharge can be directly found by hearing about the laying cable. If it is a buried cable, first confirm and indicate the direction of the cable, and then use audio amplification equipment such as deaf hearing aids or medical stethoscopes when the noise is minimal. Find.
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