Using a radio to find underground cables

Underground cables are power supply lines buried underground. If damaged, it will directly affect normal power consumption. Generally speaking, several core wires of the cable will not be damaged at the same time. Therefore, one of the intact core wires can be used to ground one end of it and pass the single-phase current of the neutral line to ground at the other end, as shown in Figure (b). Show. Slowly increase the voltage regulator TA from zero to about 5A, and repeatedly operate the knife switch S. The pulse current formed will follow the direction of the cable, pass through the lead sheath, armor, and ground surface of the cable, producing corresponding changes with the surrounding environment. Electromagnetic interference varies widely between electromagnetic waves. At this time, you can use a semiconductor radio as shown in the figure to listen along the general direction of the cable to be tested (it is best to adjust the radio to a frequency band without radio stations), and then you can hear the strongest clicks and clicks (S channel). , off) signal, but cannot be heard when far away from the cable. In this way, the actual buried position of the underground cable can be measured by determining the direction according to the strongest signal.