Explanation of the signal processing functions of infrared thermometers
Using a multimeter to measure whether there is leakage on a 220-volt line is not a good method because the multimeter measurement will have a relatively large error. The minimum current that the human body can sense is 1 milliamp; a leakage current of about 5 to 7 milliamps can cause spasms in the finger muscles; a leakage current of more than 10 milliamps can cause pain and burning in the fingers and palms; a leakage current of more than 30 milliamps can cause pain and burning in the fingers and palms. When the voltage is above milliamps, you cannot get rid of the power supply voluntarily, and your breathing begins to become paralyzed. It cannot be accurately detected by a multimeter, which easily creates the illusion that there is no leakage, and the danger continues to exist.
The way to use a multimeter to determine leakage is to measure the resistance. However, since the multimeter only supplies 9 volts, relatively large errors will occur when measuring large resistance values. After disconnecting the main line gate and disconnecting all electrical loads, you can measure the resistance value of the live and neutral wires. The resistance value should be infinite, but this method can only be used as a rough estimate and cannot be used as an accurate judgment. But when measured with a megger, if the resistance value is greater than 1MΩ, the insulation can be considered to be good.
Using a multimeter to measure leakage is far inferior to using a leakage protector to judge. Select a leakage protector with an operating current of 6 mA and connect it to the bus. If the reset button pops up after tripping, you can determine that there is leakage in the line. According to this method, the leakage protector is connected to each branch and checked step by step, and finally the leakage location can be determined. Why choose a leakage protector with an operating current of 6 mA for inspection? Because leakage current less than 6 mA does not pose a threat to the human body, the meter will not measure it.
To sum up, it is best to use a professional megger (megger) to measure the insulation resistance of the line to determine leakage. This is the most accurate judgment. Only a multimeter can be used for preliminary judgment. At the same time, it is strongly not recommended to conduct live measurement and maintenance of lines. Electrical shock accidents are mostly caused by live maintenance. Do not attempt live maintenance unless absolutely necessary.
