The multimeter is often used. This section will talk about how to test the short circuit, open circuit and leakage of the line, and how to test the short circuit and open circuit with the multimeter after the line trips.
1. Multimeter to measure short circuit
Operation method:
Insert the black test lead of the multimeter into the "com" hole and the red test lead into the "VΩ" hole, and turn the knob to the buzzer position.
Disconnect the power supply of the line to be tested, and measure the two lines of the line with two test pens respectively. If the resistance of the multimeter shows 0 and there is a beeping sound, it means that there is a short circuit in the line.
Or use the ohm 1k gear or 10k gear, disconnect the other end of the line, and test the two lines with two test pens. If the resistance of the multimeter shows 0, it means that there is a short circuit in the line.
2. Multimeter to measure open circuit
Operation method:
When measuring the continuity of the circuit, be sure to disconnect the power supply before testing.
Turn the rotary switch to the buzzer gear, and the two ends of the test line should be in contact with the metal needles of the test leads respectively. If there is a certain resistance and there is a buzzing sound, it means that the line is conducting; if the resistance is infinite, the display is 1, And there is no beep, the line is disconnected.
Or select the 10k gear of the multimeter, short the other end of the line, and test the two lines with the test pen of the multimeter. If the resistance of the multimeter shows 1, it means that the circuit is broken; if it shows 0, the line may be connected.
3. Multimeter to measure leakage
There is leakage in the line. Generally, it is not recommended to use a multimeter to test. When there is no other measurement tool, it is also possible to use a multimeter.
Operation method:
Rotate the multimeter to the AC voltage range, measure with electricity, and measure the metal casing of the equipment suspected of leakage.
When measuring, one test lead is connected to the shell, and the other is grounded. If the displayed voltage is higher than 30V, test again. If the power supply is confirmed to be higher than 30V, it means that there is leakage, and it is normal if it is lower than 30V. , After the pens of the FireWire meter are swapped, measure it once to confirm.
Summarize
Use a multimeter to test short circuits, open circuits, AC voltage, DC voltage, resistance, current, etc.
Note: The red pen is positive and the black pen is negative. When measuring, you must first check the measurement type and range. When the range cannot be estimated, first select a larger range, and then gradually change to a smaller range according to the value.
