2025-09-22
As a vital carrier of power and communications, cables play a crucial role in various projects. However, due to long-term use, environmental influences, or improper construction, cables often experience various faults, such as short circuits and breaks. To promptly restore cable operation, detecting cable fault points is crucial. The following are four commonly used methods for detecting cable fault points:
1. Bridge Method
The bridge method is a classic cable fault detection method. Based on the principle of bridge balance, it determines the fault location by measuring the resistance or reactance of the two arms of the bridge. While the bridge method is suitable for detecting low-resistance faults and is simple to operate, it has relatively low accuracy and is less effective for detecting high-resistance faults and flashover faults.
2. Low-Voltage Pulse Echometry
The low-voltage pulse echometry method utilizes the principle of electromagnetic wave reflection at the fault point. A low-voltage pulse signal is transmitted into the cable and the distance to the fault point is determined by measuring the time difference between the reflected and transmitted waves. This method is suitable for detecting low-resistance faults such as short circuits and breaks, and offers the advantages of ease of operation and high accuracy.
3. High-Voltage Flashover Method
The high-voltage flashover method is primarily used to detect high-resistance faults. By applying a high voltage to the faulty phase of the cable, a flashover discharge occurs at the fault point, creating a momentary short circuit. The fault location is then determined by measuring the discharge current waveform. While the high-voltage flashover method can detect high-resistance faults, it is relatively dangerous and requires specialized skills and protective equipment.
4. Acoustic Detection Method
The acoustic detection method uses an acoustic sensor to detect the acoustic signal generated by the discharge at the cable fault point. The propagation speed and time of the sound are used to determine the fault location. This method is applicable to various types of cable faults, especially those that are difficult to detect using electrical methods. While the acoustic detection method offers the advantages of accurate location and flexible operation, it requires favorable external environmental conditions, such as a relatively quiet location and suitable weather conditions.
