How to judge the breakpoint of electric wire and cable by digital multimeter
In addition to the measurement of basic parameters such as voltage, current, resistance, capacitance and transistors, the digital multimeter can also be used flexibly to further expand its functions and achieve the purpose of multi-purpose. Now give a method of using a digital multimeter to determine the breakpoint of the cable > wire and cable.
When there is a disconnection fault inside the cable or the cable, the exact location of the disconnection is not easy to determine due to the wrapping of the outer insulation. This problem can be easily solved with a digital multimeter. Specific method: Connect one end of the wire (cable) with a breakpoint to the live wire of the 220V mains, and the other end is suspended in the air. Pull the digital multimeter to the AC2V gear, start from the live wire access end of the wire (cable), hold the nib of the black test lead with one hand, and slowly move the red test lead along the insulation of the wire with the other hand, at this time the display shows The voltage value displayed on the screen is about 0.445V (measured by the DT890D meter). When the red test pen moves to a certain place, the voltage displayed on the display screen suddenly drops to 0.0 volts (about one tenth of the original voltage), and about 15cm forward from this position (the live wire access end) is the wire ( cable) where the breakpoint is located.
When using this method to check the shielded wire, if only the core wire is broken but the shielding layer is not broken, then this method is powerless.
Matters needing attention
1. Pay attention to the correct selection of the measuring range and the red test lead jack. When measuring an unknown quantity, the range should be adjusted to the maximum first, and then adjusted from large to small until it is suitable. If "1" is displayed, it means overcut, and the range should be increased.
2. When not measuring, turn off the power at hand.
3. When changing the range, the test lead should be disconnected from the measured point.
4. When measuring current, avoid overloading.
5. It is not allowed to use the resistance file and the current file to measure the voltage
