Method for Locating Wire Breakpoints with Digital Multimeter
In addition to measuring basic parameters such as voltage, current, resistance, capacitance, and transistors, digital multimeters can also be flexibly used to further expand their functions and achieve the goal of multi-purpose use. The method of using a digital multimeter to determine cable>wire cable breakage is now provided.
When there is a wire breakage fault in the cable or inside the cable, the exact location of the wire breakage is difficult to determine due to the wrapping of the external insulation skin. A digital multimeter can easily solve this problem. Specific method: Connect one end of the broken wire (cable) to the live wire of 220V mains power, and suspend the other end. Pull the digital multimeter to AC2V position, start from the live wire connection end of the wire (cable), hold the tip of the black probe with one hand, and slowly move the red probe along the insulation of the wire with the other hand. At this time, the voltage value displayed on the screen is about 0.445V (measured by the DT890D meter). When the red probe moves to a certain point, the voltage displayed on the screen suddenly drops to just over 0.0 volts (about one tenth of the original voltage). About 15cm forward from that position (the live wire connection end) is the breakpoint of the wire (cable).
When using this method to check shielded wires, if only the core wire is broken and the shielding layer is not broken, then this method is powerless.
Measurement of AC and DC voltage using a digital multimeter
Insert the red probe into the "V/Ω" socket and select the appropriate voltage measurement range based on the voltage. The black probe contacts the "ground" terminal of the circuit, while the red probe contacts the point to be measured in the circuit. Special attention should be paid to the fact that the frequency of measuring AC voltage with a digital multimeter is very low (45-500Hz), and the voltage amplitude of medium to high frequency signals should be measured using an AC millivolt meter.
