The method of digital multimeter to measure whether the electric wire is leaking
There are two ways to use a multimeter to measure whether the wire is leaking to the ground: one is live measurement, the multimeter is adjusted to the AC gear, and the voltage between the equipment shell and the ground is measured when the equipment is powered on. The voltage is generally tens of volts. Inductive electricity, more than 100 volts can determine that the equipment has leakage. This detection method is generally not recommended. The second method is to disconnect the power supply and measure the insulation resistance of the live wire and the neutral wire. If you use a multimeter to measure it, the leakage is generally serious and can be displayed on the multimeter. The resistance value generally ranges from several hundred ohms to tens of ohms.
Digital multimeter measurement method:
1. Adjust the multimeter to the AC gear. When the device is powered on, measure the voltage between the device casing and the ground wire (determined to be the ground wire). If the voltage range is tens of volts or 110 volts, it means that it is an induction current. , if it is 220V or 380V, it means leakage.
2. Adjust the multimeter to the AC gear. When the device is powered on, measure the voltage between the device casing and the neutral line. If the voltage range is tens of volts or 110 volts, it means that it is induction electricity. If it is 220V or 380V , it means leakage.
But strictly speaking, a megger should be used to measure whether the line insulation resistance circuit is leaking or not. The megger is equivalent to a 1000v or 500v generator. The leakage current passes through the sampling resistor inside the megger, and a sampling voltage indication is generated on the resistance. Under normal circumstances, a stable value greater than 0.5 megohm is qualified.
Methods as below:
1. Cut off the power of the equipment, fully discharge it, take safety measures and hang a warning sign, and then untie the terminals on both sides of the cable to be tested. Never allow the equipment to be charged for measurement to ensure the safety of personnel and equipment.
2. Before measuring, check whether the megohmmeter is in normal working condition, mainly check its "0" and "∞" points. That is, shake the handle to make the motor reach the rated speed. The megohmmeter should be at the "0" position when it is short-circuited, and it should be at the "∞" position when it is open-circuited.
3. Connect the “L” wire end button to the conductor of the equipment under test, the “E” ground terminal button to ground the equipment shell, and the “G” shield terminal to connect to the insulation part of the equipment under test. Turn the megger at an average speed of 120 rpm. If the reading is stable and greater than 0.5 megohm, it is qualified, otherwise, the degree of insulation is not enough, and there may be leakage.
