In actual engineering maintenance and repair, the most […]
In actual engineering maintenance and repair, the most fearful thing for maintenance personnel is that they cannot find out where the breakpoint is when the wires and cables are broken. Although when we are actually repairing the weak current project, we will directly find a way to change the cable or re-lay the cable when we encounter a cable problem, but today we are discussing what technical methods are available to detect the cable breakpoint!
When the internal medium of the cable is broken, the exact location cannot be seen when the external insulation is covered, including strong and weak currents. Usually, the idea of finding the breakpoint is to investigate in sections.
For example, if there is a problem in the middle of a cable, you can measure from the two ends and three points in the middle, and take the middle point to measure which side is blocked. In this way, you can quickly find the location of the breakpoint by troubleshooting.
So under normal circumstances, what are the measuring methods to accurately measure the electrical wire and cable breakpoint?
1. Multimeter testing method:
The first is to connect one end of the unconnected cable to the live wire of the strong current, and leave the other end empty. Set the multimeter to the AC2V position. Starting from the cable connection end, hold the black pen tip while slowly moving the red pen along the insulation of the wire. At this time, the voltage value displayed on the display is about 0.445V .
When the red test lead moves to a certain place, the voltage displayed on the display suddenly drops to a few volts, which is about one-tenth of the original voltage. The breakpoint is about 15cm from this position forward (the hot wire access terminal) .
2. Inductive electric pen detection method
The induction test pen is a device with an electronic screen that can detect voltage and on-off. First, remove the power supply from the cables around the breakpoint cable, then connect the breakpoint cable to the live wire, put the electric pen perpendicular to the wire, press and hold the "inductive breakpoint test" button to move slowly forward on the wire, and wait for the test pen to test When the AC signal suddenly disappears, it can be judged that the breakpoint is at the detection point, and the error is no more than 10cm.
It should be noted that the cables around the broken wire cannot have power. Another thing to remind is that this method is not omnipotent, the effect of short cables is obvious, and the longer the cables, the worse the effect.
3. Use audio sounder
Audio sounder is an instrument that uses single-frequency or multiple-frequency signals to test the continuity of the line to identify line faults. It can directly find the line when connected to any switch, router, PC terminal. When tracing the cable circuit, there is no need to strip the outer skin of the circuit, which is simple and quick, and the position of the circuit breakpoint can be determined.
4. Cable fault tester
It is a comprehensive cable fault detection instrument. It can test cable high-resistance flashover faults, high and low-resistance grounding, short circuit and cable disconnection, poor contact and other faults. If equipped with an acoustic measuring point meter, it can accurately determine the precise location of the fault point. It is especially suitable for testing various types of power cables and communication cables of different voltage levels.
5. Broken line detection method
Connect one end of the wire with the breakpoint to the black test lead of the multimeter and the other end to the red test lead. The multimeter is set in the resistance range of 200Ω. Bent back and forth in the most likely place to break (such as frequent bending points). If the multimeter shows that it is switched on and off, this is the breakpoint. If you still can’t judge, you need to bend from one end of the cable until you find the break point. This method is suitable for shorter cables.
6. Acupuncture detection method
This method is a damaged detection method. Insert steel needles into the broken cable in sections, and use a multimeter to measure the connection and disconnection of the steel needle to the end of the cable to determine the breakpoint of the cable.
Under normal circumstances, it is not recommended to use, because it will damage the insulation layer, it is easy to cause other problems in the later use of the cable, especially in a humid environment. This method is to use the on-off of the cable to troubleshoot the breakpoint of the cable.
7. Pull wire detection method
This is also a damaged detection method, which is generally not used in practice, but it is also a method listed together. Use a vise to pull the broken wire at the cable end. If the break point is near the cable end, it is insulated The skin breaks easily. This method is used for cables whose breakpoint is near the end of the cable.