When the breakpoint fault occurs in the cable or inside of the cable, it is difficult to determine the location of the breakpoint intuitively due to the wrapping of the external insulation.
The following is to introduce several methods to judge the breakpoint of wire and cable
The method of no damage cable
First, connect one end of the cable with breakpoint to the 220 V live wire, and make the other end suspended. Adjust the gear of the multimeter to AC 2V. Then, starting from the live wire access end of the faulty cable, hold the black pen tightly with one hand, and the red pen slowly slides along the insulation layer of the faulty cable. The voltage of the cable without breakpoint is about 0.445v. When the red probe moves to a certain place, the voltage value displayed by the multimeter drops to 1 / 10 of the normal voltage, that is, 0.04V. At this time, it can be concluded that the breakpoint is 15cm forward of the position (the live line access end).
If the shielding layer of the shielding wire is not damaged, this method cannot be used.
Induction pen method
First, eliminate the power supply of the ACSR Cable around the breakpoint cable, then connect the cable with breakpoint to the live wire, and then use the induction pen to move vertically to the cable slowly. When the AC signal of the induction pen disappears, it can be judged that the breakpoint is at the detection point, and the error is not more than 10cm at most.
Broken line method
For the short cable test break point, the bending method can be used to connect the two 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. According to this method, it has been checked until the breakpoint（ To learn more cable technology, please click here. A large amount of dry goods are waiting for you.)
Methods of repairing damaged cables
This method is to use the on-off of the cable to check the breakpoint of the cable. Insert the steel needle into the breakpoint cable section by section, and then use the multimeter to measure the on-off condition in turn. Different points are where the breakpoint is. However, this method will damage the insulation layer, which is easy to cause other problems in the later use of the cable.
Methods of professional instrument testing
1. In addition, for the judgment of underground cable fault point, the audio detector can be used to judge the fault point.
2. The cable fault telemeter can be used to judge the full length of the cable and the short circuit and open circuit points
3. According to the actual situation, different methods are used to determine the breakpoint. The above methods can basically determine the breakpoint of the cable.