How to use a multimeter to measure the continuity of live lines
In electrotechnics, in electric drive, electricity is divided into weak electricity, strong electricity, low voltage, high voltage, and ultra-high voltage. However, there are strong or even high-voltage electricity in the weak electricity, such as TV sets, switching power supplies, and LED light power supplies, which are as weak as a few volts and as high as more than 10,000 volts. There are low voltage and weak current in high voltage, because the control system controls low voltage to control high voltage, and weak current to control low voltage, for the sake of safe operation.
If you simply use a multimeter to measure the continuity of the live line, I don't agree! You can use an electric test pencil to measure whether there is electricity, or you can use an ohm block to measure the quality of the line after the power is turned off.
Electrician is a high-risk industry, sometimes it is necessary to measure data, and there is no way to measure the actual data voltage and current without electricity. and waveform diagrams. Live measurement is also live work. Although there are labor protection supplies, insulating gloves, and insulating shoes, it is really inconvenient for that guy to bring it to work. Friends, tell me that the work is difficult!
As for how to use the multimeter, you can read the manual and go to Baidu. Everyone has answered very well and I won’t repeat it. What I want to express is how to use the multimeter for safer work and safer use of the live measurement precautions.
1. Measure weak current with live current
When measuring, do not measure blindly first, check the weak current and strong current in the circuit, select the gear, and measure the voltage below DC and AC24V. large capacitor.
When measuring high voltage in low-voltage equipment, the best way is to cut off the power first, discharge (including capacitors), then select the gear of the test pen, place the measurement point, and then send power to read the measurement data. The digital multimeter has a memory button. , you can press the memory key, which will be safer.
When the multimeter is used to measure the voltage with electricity in the factory, the line may not be connected if there is voltage, and the line without voltage must not be connected.
Because it is a live measurement, there is a transformer in the line, there is a motor, there is electricity on the breakpoint, and there is electricity under the breakpoint. The electricity on the breakpoint is the power supply, and the electricity under the breakpoint is the electricity from another phase through the winding or coil. , we must pay attention to this phenomenon. Therefore, it is inaccurate to measure the continuity of the live line with a multimeter! For the mains electricity, it should be single-phase electricity. If the live line is broken, there will be no power supply, but if the neutral line is broken, it will be detected that there is power and no voltage.
To sum up, it is correct to use a multimeter to measure whether the circuit is on or off. If you can’t make it yourself, the best way is to use an ohm block after power off, or use a shaker to measure the circuit’s on-off is more accurate.
