Methods for Locating Cable and Wire Breakpoints with a 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 wire and cable breaks 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.
How to determine (test) whether the DC voltage range (DCV) of a multimeter is good?
When testing, the first step is to find the testing source. As we are qualitative with a little quantitative measurement, there are many available testing sources. Household testing sources include 1.5V alkaline/carbon batteries (No. 1, No. 5/AA, No. 7/AAA), 1.2V rechargeable batteries, mobile phone chargers, power adapters, and so on. When testing, turn the multimeter to the desired DC voltage range, insert the probes according to the instructions, connect the testing source, and read the reading on the LCD. As long as the measured value is around the nominal voltage, it is sufficient.
