How to Measure Live Line Continuity Using a Multimeter
In electrical engineering and electric drive, electricity is divided into weak electricity, strong electricity, low voltage, high voltage, and ultra-high voltage. But there are strong and even high voltages in weak electricity, such as televisions, switch mode power supplies, LED light power supplies, ranging from a few volts to over 10000 volts. There are low voltage and weak voltage inside the high voltage, because the control system controls both low voltage and high voltage, and weak voltage controls low voltage for operational safety.
I do not approve of using a multimeter solely to measure the continuity of live circuits! You can use an electrical tester to measure the presence or absence of electricity, or you can use an ohm switch to measure the condition of the circuit after power is turned off.
Electricians are a high-risk industry that sometimes requires measuring data. Without electricity, it is impossible to measure actual data such as voltage and current. And waveform diagram. Live measurement also belongs to live work. Although there are personal protective equipment, insulated gloves, and insulated shoes, it is truly inconvenient for that guy to bring work with him. Friends, let's talk about how difficult the work is!
As for how to use a multimeter, you can refer to the manual and go to Baidu. Everyone has answered very well, so I won't repeat it. What I want to express is how to use a multimeter more safely for live measurement precautions.
Live measurement of weak electricity
When measuring, do not blindly measure first. Check the weak and strong electricity in the circuit, choose the appropriate gear, and measure voltages below DC and AC24V. There is basically no danger, but do not touch the mains power, high voltage parts in the equipment, and large capacitors.
The best way to measure high voltage in low-voltage equipment is to first turn off the power, discharge (including capacitors), then select the appropriate gear for the probe, place the measuring point, and then power on to read the measurement data. The digital multimeter strap has a memory button, which can be pressed to ensure safety.
Due to the live measurement, there are transformers and motors in the circuit, and there is electricity on and off the break point. The electricity on the break point is the power supply, and the electricity below the break point is another electricity that passes through the winding or coil series. It is important to pay attention to this phenomenon. So using a multimeter to measure the continuity of a live circuit is inaccurate! For mains power, it should be single-phase power. If the live wire is disconnected, there will be no power supply, but if the neutral wire is disconnected, the phenomenon of having power but no voltage will be detected.
