If a wire is broken internally, how to use a multimeter to determine the point of breakage
Due to manufacturing processes or external stress, wires may sometimes be broken internally. When an internal break occurs in a wire, how can you use a multimeter to quickly determine the break point? Two methods can be used: measuring resistance or measuring voltage.
The two ends of a section of wire are end A and end B respectively, and point O is the midpoint of this section of wire. We can first use the ohm range of the multimeter to measure whether point A and point O are connected. If they are connected, it means that the fault point is in section O~B. If there is no conduction, it means there is a fault point in the A~O section. After determining which half of the fault point is located, use this method to gradually narrow the range half by half until the fault point is found.
Using this method, the test leads of the multimeter may not be long enough and can be extended with other wires. You can also add a voltage of 220 volts to terminal A, and use the AC voltage range of a multimeter to measure the voltage to ground at point O. If the voltage is normal, the fault is in sections O~B. The specific measurement method is the same as the resistance measurement method. This method does not require extending the test leads of the multimeter, but you must pay attention to safety when making live measurements.
For stranded wires, you can first twist the wires at one end together.
A, B, and C are three wires wrapped in the same insulator. One of them is broken. Let's first connect a section of wire. Then use the ohm setting of the multimeter to measure the three points A, B, and C respectively. If A and B are connected, A and C are not connected, and B and C are not connected, then the disconnection point must be on the C wire. This method can also be used to determine which conductor the fault point is on.
Of course, it can also be measured using the voltage method. Connect the connected ends to 220 volts, and then use a multimeter to measure the voltage to ground at three points A, B, and C. If the voltage to ground at any point is absent or abnormal, indicate which wire the fault is on. . After determining which conductor the fault point is on, use the "half-section" rule mentioned earlier to investigate step by step.
The half-section method to troubleshoot the fault point of the wire requires destroying the insulation of the wire. A little work experience, for reference only. Nowadays, there are special cable breakpoint detection instruments, but they may be more expensive. I have not used them.
