The Common Method of Measuring Leakage with Multimeter
Regarding the usage of the multimeter, let me talk about how to use the multimeter to measure the leakage. Whether the line is leaking, you can use the on-off gear of the multimeter to judge whether it is insulated by the resistance value measured on the multimeter, so as to determine whether there is leakage.
Requirements: Use the on-off gear of the multimeter to measure the ground and the circuit to be measured, and check whether there is resistance on the meter, and judge whether it is leakage or insulation based on this.
Insert the multimeter connector into the terminal corresponding to the measurement of alternating current, then use one pen to measure the zero line or ground wire, and the other pen to measure the place where the leakage is suspected, and look at the value displayed on the multimeter. If it is 0, it means no leakage and no voltage . If it is 220 or other voltage readings exceeding 36V, it means that there is leakage here.
Measure the insulation resistance with the 200M resistance range of the multimeter, first determine which wire is leaking, or which two wires are short-circuited.
Measurement methods:
Measure the insulation resistance of the live wire and the neutral wire, measure the insulation resistance of the live wire to the ground wire, and measure the insulation resistance of the neutral wire to the ground wire. If the short circuit insulation resistance is basically zero.
Know which line is leaking, and use the segmented search method to gradually narrow down the scope of the fault. Or use the elimination method to separate the lines and conduct power-on tests one by one.
Precautions:
To measure whether there is leakage in the circuit, a megger is generally used, that is, a shaker.
When the multimeter is measuring, the voltage at both ends of the test pen is very low, generally not more than 9v, and the gap leakage cannot be broken down, while the megohmmeter can reach more than 1000v.
How to Quickly Check Leakage with Multimeter
Leakage fault finding and analysis
First ask the repairing user what is the fault phenomenon and what are the obvious features; secondly, observe whether there is an intuitive fault point from the surface, and then proceed to the next step of inspection.
1. First disconnect the main isolating switch of the user's power incoming line, and turn off all the user's electrical loads, such as unplugging the refrigerator, disconnecting the water pump switch, etc.
2. Put the gear of the digital multimeter on the 200M gear of the ohm gear, place one test lead on one of the two outlets on the load side, and the other test lead touch the wall, preferably the grounding wire or a temporary Ground wire.
After the number displayed on the multimeter is stable, the insulation resistance value of the main line is read. If the insulation resistance value is less than 0.5 megohm, then there is a problem with the main line. If the insulation resistance is above 0.5 megohm, it can be ruled out. It's a problem with the main line.
Use the same method to measure another wire, and judge whether there is a problem with the main line according to the value displayed on the multimeter.
3. Check the insulation resistance value of the shunt and each electrical appliance, and use the same method to check one by one until the fault point is found.
Operation precautions:
1. When using the 200M gear of the ohm gear of the multimeter, be careful not to touch the metal part of the test pen with your hands when measuring, otherwise the reading will be inaccurate.
2. When measuring various electrical equipment, pay attention to discharge first to prevent the capacitive current in the electrical equipment from hurting people.
This is a relatively safe way to find the fault point in the state of no electricity. In addition, this method is also applicable to the search for power users and power plant leakage.
