When a breakpoint occurs inside a wire or cable, it is difficult to visually determine the location of the breakpoint due to the wrapping of the external insulation.
Here are some quick ways to identify breakpoints:
Method of non-damaged cable:
Digital multimeter method
First connect one end of the breakpoint cable to the 220V wire and leave the other end dangling. Adjust the multimeter’s gear to ac 2V. Then, starting from the firewire access end of the faulty cable, one hand grasps the black marker pen, and the red marker slowly slides along the insulation layer of the faulty cable. The voltage of the cable without breakpoint is about 0.445V. When the red watch pen moves to a certain place, the voltage value displayed by the multimeter drops to 1/10 of the normal voltage, i.e. 0.04V. At this point, it can be concluded that the breakpoint is 15cm forward (firewire access).
This method cannot be used if the shield layer of the shield wire is not damaged.
Two, induction pen method
Firstly, it is excluded that there is power supply in the cable around the breakpoint cable. Then, the cable with breakpoint is connected to the fire line. Then, the induction pen is used to move slowly perpendicular to the cable.
Three, broken line method
For short cable test breakpoints, bend the two ends of the cable to the two ends of the red and black watch pen of the multimeter. Bend back and forth from one end of the cable. If the multimeter goes on and off at this point, the break point is here. Follow this method until you reach the break point.
Damaged cable methods:
Four. Acupuncture discrimination method
This method USES the on and off of the cable to check the breakpoint of the cable. Insert the steel needle on the breakpoint cable in sections, and then measure the on-off condition using a multimeter in turn. The difference is where the break point is. However, this method will damage the insulation layer, which is easy to cause other problems in later cable use.
Five.Methods of professional instrument detection
1. In addition, the fault point of underground cable can be judged by audio detector.
2. The cable fault telemeter can be used to determine the length of the cable as well as the short circuit and open point.
3. Different methods are used to determine the breakpoint location according to the actual situation. The above methods can basically determine the breakpoint location of the cable.