The Method of Judging the Breakpoint of Electric Wire and Cable with 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 the method of using a digital multimeter to judge 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 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.
Digital multimeter AC and DC voltage measurement
Insert the red test lead into the "V/Ω" jack, select the appropriate voltage measurement range according to the voltage, the black test lead touches the "ground" end of the circuit, and the red test lead touches the point to be measured in the circuit. In particular, it should be noted that the frequency of the AC voltage measured by the digital multimeter is very low (45 ~ 500Hz), and the voltage amplitude of the medium and high frequency signals should be measured by an AC millivolt meter.
