useCable fault testerWhen testing, it is necessary to strictly follow the operating procedures and safety requirements to ensure accuracy and avoid personal or equipment damage. The following are specific operational precautions:

Accuracy of parameter settings

Wave velocity calibration: Input the correct wave velocity (common value: 160-172m/μ s) according to the cable type (such as cross-linked polyethylene, oil immersed paper), and an error of more than 5% will cause positioning deviation.

Range selection: Set the appropriate testing range (such as 0-1km or 0-10km) according to the cable length to avoid signal overflow or insufficient resolution.

Pulse width adjustment: Narrow pulses (0.1-0.5 μ s) are selected for low impedance faults (<200 Ω), and wide pulses (1-5 μ s) are selected for high impedance faults (>200 Ω) to optimize the clarity of the reflected signal.

Wiring standardization

Low voltage pulse method: The output end is connected to the faulty phase conductor, the grounding end is connected to the shielding layer or ground wire, and the far end must be suspended (not grounded).

High voltage flashover method: Connect the high-voltage output terminal to the faulty phase, and connect the grounding terminal to the armor or ground grid to ensure a secure connection without looseness.

Avoid cross wiring: To prevent signal interference or short circuits, a secondary inspection and confirmation is required after wiring.

Waveform analysis and interference elimination

Multiple testing comparison: Conduct more than 3 tests on the same fault point and take the average to improve accuracy.

Filter out interference signals: If there is clutter in the waveform (such as interference from frequency converters or wireless base stations), the sampling rate can be adjusted or wavelet transform algorithm can be used for filtering.

Distinguishing between true and false faults: The low amplitude of the reflected pulse may be caused by joints or bends, and it needs to be confirmed through path detection.