How to use a digital multimeter to detect breakpoints in cables and wires
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.
The method of judging the breakpoint of the wire and cable with a digital multimeter: When the cable or cable has a broken line inside, due to the wrapping of the outer insulation,
Make it difficult to determine the exact location of the broken wire. 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 AC2V gear,
Starting 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 voltage value displayed on the display is about 0.445. About V (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),
About 15cm forward from this position (live wire access end) is where the breakpoint of the wire (cable) is.
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.
How to measure three-phase voltage with a digital multimeter
1. Adjust the knob of the multimeter to the V~ position and point to 750V (this position does not have to be 750, it can be greater than 380),
2. Insert one end of the red and black stylus into the com and VΩmA jacks of the multimeter respectively, the black stylus into the com jack, and the red stylus into the VΩmA jack
3. Turn on the multimeter, and touch the other ends of the two stylus to the line under test (note: the voltage between each live wire and the neutral wire of the three-phase power is 220V, and the voltage between the two live wires is 380V)
4. The reading displayed on the screen is the voltage value to be measured.
