In recent years, Zhongshan has promoted integrated urban and rural development, resulting in a very high cable coverage rate. With the continuous increase in electricity load, 10kV cables frequently experience faults. Emergency repairs are urgent and difficult, and outdated equipment has made fault location a weakness for each power supply branch, constantly troubling their emergency repair teams. Old Xu, the head of the emergency repair team at the Dachong Power Supply Branch, told reporters, "Previously, the branch's emergency repair team used a bridge cable to locate faults. This equipment has significant limitations, often making it difficult to pinpoint the fault location for various reasons. Usually, we have to uncover the fault after the load is brought up by another line, sometimes taking several days, seriously affecting cable repair work." "There are many fishponds in Dachong, all of which cannot be without power, making cable faults the most troublesome issue." The power supply branch's emergency repair team only maintains lines below 10kV, a voltage level not considered high for the power grid. Their equipment and technical capabilities are not as strong as those of the transmission management department. Whenever they encounter cable repair problems, they have to consult with others or borrow tools, wasting considerable time.
Each branch office held multiple meetings to address this problem, collaborating with the equipment management department to research solutions. Finally, a plan was decided upon for the transmission management office to temporarily provide assistance. According to Zhang Zhifang, the head of the cable team at the transmission management office, upon arriving at a 10kV fault site, the "three-pulse method" is typically used to roughly determine the location of the cable fault. If no fault waveform appears, indicating a high-resistance fault, a DC high-voltage test is immediately initiated to burn through it. Finally, a rough measurement allows for precise location. These methods are commonly used when managing main grid cables. Due to the high voltage levels, they require precision instruments and qualified personnel, making them particularly challenging for the emergency repair team managing the distribution network. Currently, locating a 10kV cable fault takes less than half an hour.
