How to use a digital multimeter to measure the continuity of a live circuit
A commonly used digital multimeter, there are four holes at the bottom of the digital multimeter, one black hole is the COM terminal, which is used to insert the black needle; three red holes are used to measure high current, small current, voltage resistance and diode. ;
The middle part of the digital multimeter is the gear adjustment of the multimeter. Looking at the picture above, it can measure AC voltage, DC voltage, resistance and diode, capacitance and AC and DC current;
The top of the digital multimeter is a digital display screen, and there are two buttons below the screen, which are the data retention button and the manual or automatic range selection button.
The above are all the functions of the multimeter. The next step is to use the multimeter to measure the continuity of the live line. The specific method is (be careful of the danger of electricity, and non-professional electricians should not try):
Insert the black test lead into the COM hole, and the red test lead into the voltage resistance hole, which is the rightmost one of the four holes below the digital multimeter;
The first method: Use the voltage gear to detect the on-off of the live line, and rotate the digital multimeter to the AC voltage gear. The AC voltage gear of each digital multimeter is not the same, and the one with the highest voltage can be selected;
Then, use the black test lead and the red test lead to touch the zero line and the live line of the line respectively. If the value displayed on the display is about 220V (about 380V for three-phase power), then the line is a channel; if the displayed value is zero, then the live line It is an open circuit; then, use the test leads to connect the live wire and the ground respectively, and look at the displayed value. If the measured value is the same as the voltage between the live wire and the neutral wire, then the neutral wire is grounded.
The second method: use the buzzer to directly detect the on-off of the line, and the black and red test pens are still inserted in their original positions;
Then adjust the gear of the digital multimeter to the buzzer, and use the black and red test leads to connect the neutral and live lines respectively. If the multimeter indicator light flashes or beeps, then the line is the path; if the indicator light is off, and If there is no beep, then the line is shorted.
