How to use a multimeter to measure cable breakpoints
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. 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.
This method can also be used to find the breaking point of resistance wires such as faulty electric blankets.
Instructions
(1) Mechanical zero adjustment is required before measurement
(2) Select the appropriate range, choose the large range first, and then select the small range or see the nameplate value for estimation.
(3) When the minimum measuring range is used to measure and the reading is not obvious, the measured wire can be wound several times, and the number of turns should be based on the number of turns in the center of the jaw, then the reading = indicated value × range / full deviation × turns number
(4) When measuring, the wire under test should be in the center of the jaws, and the jaws should be closed tightly to reduce errors.
(5) After the measurement is completed, the transfer switch should be placed at the maximum range.
3) Precautions
(1) The voltage of the line under test should be lower than the rated voltage of the clamp meter.
(2) When measuring the current of a high-voltage line, wear insulating gloves, wear insulating shoes, and stand on an insulating mat.
(3) The jaws should be closed tightly and the range cannot be changed with power on.
