How to use a digital multimeter to determine the breakpoints of wires and cables
In addition to measuring basic parameters such as voltage, current, resistance, capacitance and transistors, digital multimeters can also be used in various ways to further expand their functions and achieve the purpose of a multi-purpose meter. Here is a method to use a digital multimeter to determine the breakpoint of cables > wires and cables.
When a wire break occurs within a cable or cable, the exact location of the wire break is difficult to determine due to the wrapping of the outer insulation. This problem can be solved easily with a digital multimeter. Specific method: Connect one end of the wire (cable) with a breakpoint to the live line of the 220V mains power, and leave the other end floating. Pull the digital multimeter to AC2V, start from the live wire access end of the wire (cable), hold the tip 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 The voltage value displayed on the screen is approximately 0.445V (measured by DT890D meter). When the red test lead moves somewhere, the voltage displayed on the display suddenly drops to 0.0 volts (about one-tenth of the original voltage). About 15cm from this position forward (the live wire access end) is the wire ( Cable) break point.
When using this method to check the shielded wire, if only the core wire is broken but the shielding layer is not broken, this method is powerless.
Digital Multimeter Overview
The digital multimeter is a small digital multimeter with a three-and-a-half-digit LCD display. It can measure AC and DC voltage and AC and DC current, resistance, capacitance, transistor β value, diode conduction voltage and circuit short circuit, etc. The measurement function and range can be changed by a rotary band switch, with a total of 30 levels.
The maximum display value of this multimeter is ±1999. It can automatically display "0" and polarity. It displays "1" or "-1" when overloaded. When the battery voltage is too low, it displays the "←" mark. There is a buzzer for short circuit inspection. .
