How to measure the leakage of household appliances with digital multimeter
Multimeters are still widely used in our work. Their main functions are to measure resistance, AC voltage and DC voltage. Some multimeters can also measure capacitance, inductance, diode, triode, level and temperature.
By measuring the resistance, the multimeter can judge the size of the resistance, the quality of components, the on-off and short-circuit of the line, and the presence or absence of grounding fault (leakage). By measuring the voltage, we can not only know the voltage, but also judge the quality of components, line connection and disconnection, load size, grounding fault (that is, leakage) and other phenomena. Multimeters are generally not used to measure current, and clamp ammeters (clamp meters for short) are generally used to measure current.
How to measure the leakage of electrical appliances with multimeter?
Before talking about how to measure the leakage of electrical appliances with multimeter, I have to say a premise: using multimeter to judge whether there is leakage is only suitable for contact leakage or very serious leakage. (For example, the broken skin of the wire touches the shell, and the circuit board touches the shell somewhere. )
For non-contact leakage, such as leakage caused by insufficient insulation strength of wires or insulators, multimeter can't measure it. In this case, it is necessary to use a more professional instrument for measuring leakage-megohmmeter.
Measuring leakage with multimeter resistance.
First, disconnect the power supply, and turn the multimeter to the resistance gear (try to use a large gear). Then, one probe of the multimeter is connected to the tested wire or equipment, and the other probe is connected to the equipment shell or the ground wire connected to the shell.
If the multimeter shows that the resistance is zero, it means that the measured object is leaking electricity, and the leakage is very serious.
If the multimeter shows infinite resistance, the measured object is normal.
If the multimeter shows a certain resistance, it means that the measured object is leaking, but the leakage may not be very serious.
Measuring leakage with multimeter voltage range
We can also judge whether there is electricity leakage by measuring whether the equipment shell is charged. The measurement method is to set the multimeter to the voltage range, with one probe connected to the equipment shell and the other probe grounded (the ground wire must be regular, and the false ground wire is meaningless). If a certain voltage is measured, it means that the tested equipment has leakage; If the voltage is zero, the device under test is normal.
