How to use a meter to measure whether a circuit is grounded with a resistance file
How to use a multimeter to measure whether a circuit is grounded with a resistance gear. First, regardless of measuring any line or equipment, you must first measure the voltage to ensure that it is safe and voltage-free, and then perform other measurements. If it is a capacitor or a device with capacitive reactance, you must first discharge it, and then confirm that it is safe and voltage-free; then adjust the gear of the multimeter to 2000 megohms. Generally, leakage protectors greater than 0.5 megohm and 30 mA will not trip for protection, so it is generally considered that the line or equipment is not grounded. But it also depends on the working voltage of the equipment or line or various technical requirements.
In daily life, as for the wide range of circuits, I don’t know which circuit you are referring to. There are electronic circuits, electric money circuits for transmitting voltage, and motor circuits. Let’s take these three commonly used circuits as examples to talk about how to use a multimeter to measure whether it is grounded.
1. Electronic circuit, under normal circumstances, the measurement electronic circuit chooses universal
The gear of the meter is the maximum gear of 10k gear. At this time, the measured resistance value is almost close to 10K. The pointer moves slightly, and then the test leads are reversed for measurement. Some electrical test leads will be different after being reversed. Therefore, it usually makes people feel numb. This kind of circuit cannot be measured with a shaker, which will damage the electronic parts.
2. Voltage transmission circuit, take the household lighting circuit as an example. Before measuring, first turn off the power switch, and at the same time turn off the switches of all electrical appliances, and then measure the grounding situation. If a multimeter is used to block the resistance of the circuit to the ground, the resistance of the live wire and the neutral line should be infinite. If you want to call it a shaker), the measured resistance value must be greater than 0.5 megohms to ensure that the circuit does not leak.
3. The measurement of the motor circuit to the ground is not possible with a multimeter. It is also necessary to use a 500-volt megohmmeter to measure. The resistance of the coil circuit to the ground must be greater than 0.5 megohm, which is considered safe. If it is a newly wound motor coil, the resistance to the ground must be greater than 10 megohm. Therefore, each circuit has different requirements for the resistance value of the ground, and the high voltage requires a large insulation resistance value for the ground.
