When there is a breakpoint fault in the cable or the inside of the cable, it is difficult to intuitively determine the determined position of the breakpoint due to the wrapping of the external insulation. The following is a brief introduction to several methods for judging the breakpoints of wires and cables:

　　1、 Method of no damage cable

　　Digital multimeter method

　　First connect one end of the cable to the 220V wire with a breakpoint, and then hang the other end. Change the multimeter to ac-2v. Then, from the live wire access end of the fault cable, one hand holds the black contact, and the red contact slides slowly along the insulation layer of the fault cable. When the red contact pin moves somewhere, the voltage value displayed by the multimeter drops to one tenth of the normal voltage, or 0.04 v. at this time, it can be concluded that the breakpoint of the cable at the forward position (fire terminal) is 15 cm.

　　This method cannot be used if the shielded wire is not broken.

　　Induction pen method

　　First of all, we can eliminate the power supply of the cable around the breakpoint cable enterprise. Then we connect the cable with a breakpoint to the live wire, and then use our own induction pen to move slowly perpendicular to the cable. When the AC learning signal of the induction pen disappears, it can be used as a judgment that the breakpoint is at the detection point, and the error is not more than 10cm at most.

　　Broken line methoda

　　For short cable test breakpoints, the method of bending can be adopted. Connect both ends of the cable to the red and black probes of the multimeter. Bend back and forth from one end of the cable. If the multimeter is on and off at this time, the breakpoint is here. Follow this method until the breakpoint.

　　2、 Methods for damaged cables

　　Acupuncture discrimination

　　This kind of teaching method is to use the network cable to check the breakpoint of the cable. The steel needle can be inserted into the section on the breakpoint cable, and then the digital multimeter can be selected to check and measure the on-off status. The difference is the breakpoint. However, this method will damage the insulation layer, which is easy to cause other problems in the later use of cable enterprises.

　　3、 Instrument test method

　　1. In addition, the fault point of the underground cable can be judged by the audio detector.

　　2. It is used for the whole length of the cable and to determine the short circuit and point. The telemeter cable fault can be used.