The diagnosis of cable fault nature, in essence, refers to determining: whether the fault resistance is high or low; whether it is a flashover or a closed-type fault; whether it is grounding, short circuit, breakage, or a combination of these; whether it is a single-phase, two-phase, or three-phase fault. With the HZXT series cable fault tester, multiple methods for detecting cable faults have been adopted. By applying the achievements and components of contemporary electronic technology, using computer technology and special electronic technology, combined with the long-term successful experience in developing cable fault testers by Wuhan Guodian Xigao, a high-tech, intelligent, and fully functional new cable fault detection equipment has been launched.
1. Bridge method: Connect the faulty phase and the non-faulty phase of the tested cable terminal. Connect the two arms of the bridge to the faulty phase and the non-faulty phase respectively. Adjust the resistors to make the bridge balanced. Then, calculate the distance of the fault point using the formula.
2. Low-voltage pulse reflection method: During the test, a low-voltage pulse is injected into the faulty phase of the power cable. When this pulse travels along the cable to the impedance-mismatched point (i.e., the fault point), it is reflected and sent back to the test point, where it is recorded by the instrument. Based on the time difference between the emitted pulse and the reflected pulse and the wave speed of the pulse in the cable, the distance from the test point to the fault point can be calculated.
3. Pulse Current Method: The pulse current method involves applying high voltage to the cable fault point to create a breakdown. An instrument is then used to collect and record the electrical wave signals generated by the breakdown at the fault point. By analyzing these signals, the round-trip time of the electrical wave signal between the measurement point and the fault point is calculated to determine the fault distance. The pulse current method uses a linear current coupler to collect the electrical wave signals in the cable.
The HZXT series of cable fault testers is a comprehensive set of cable fault detection instruments. It can test various faults in cables, including high-resistance flashover faults, grounding faults of different resistances, short circuits, cable breaks, and poor contact. If equipped with an acoustic positioning instrument, it can accurately determine the precise location of the fault point. It is particularly suitable for testing faults in various types and different voltage levels of power cables and communication cables.
Common methods for locating cable faults
1. Acoustic Location Method: The acoustic location method is the main method for locating cable faults. It is mainly used to measure high-resistance and flashover faults. During the measurement process, high-voltage equipment is used to cause the fault point to break down and discharge. The mechanical vibration generated during the discharge of the fault gap is transmitted to the ground, resulting in the sound of “popping, popping”. This phenomenon can be used to accurately locate cable faults, but it has the disadvantage of being greatly affected by external interference.
2. Sound-Magnetic Method: When an impact high-voltage signal is applied to the cable to cause the fault point to discharge, an induced current will be generated in the circuit formed by the cable’s outer skin and the ground. This current will create a pulsed magnetic field around the cable. At the same time as listening to the sound signal, receiving the pulsed magnetic field signal allows us to determine that the sound is caused by the discharge at the fault point, and the fault point is nearby.
3. Audio Induction Method: This method is typically used to detect low-resistance faults with a resistance less than 10Ω. During the detection process, a 1 kHz audio signal generator is used to supply audio current to the cable to be tested, generating electromagnetic waves. Then, a probe is used to receive the electromagnetic field signals along the path of the tested cable on the ground and send them to an amplifier for amplification.
In the process of detecting faults in power cables, one should carefully and calmly analyze the type and nature of the fault, correctly apply the search methods and instruments, and accumulate more experience in fault detection.
Post time: Jun-05-2026