Time-frequency Characteristics of External Breaking Vibration of Distribution Cable Trench

The distribution cable trench plays a crucial protective role in the urban power distribution network, and the impact of external vandalism (e.g., construction or theft) on the trench can significantly threaten the stability of the power supply system. However, existing research on vibration detection related to external breakage of distribution cable trenches is predominantly conducted in laboratory settings, with limited field-based studies reported. Therefore, this paper establishes an experimental platform utilizing piezoelectric accelerometers to analyze the time-frequency characteristics of vibration signals generated by various types of external breakage, as well as the variation in signal amplitude relative to the distance from the point of impact. The experiments involved electric picks, hand picks, and excavators within a real cable trench environment. Results indicate that the frequency bands of the vibration signals generated by different external breakage behaviors are within 1.2 kHz. Specifically, the frequency band of the vibration signals from the electric pick impacting the trench is concentrated within 500 1000 Hz, while hand pick vibrations are primarily below 500 Hz, especially concentrated around 200 Hz.Additionally, vibrations caused by excavator pickaxes are within 300 Hz, with a notable characteristic frequency of 50 Hz. These findings provide a theoretical basis for monitoring external breakage in power distribution cable trenches.