How to use a multimeter to measure the on-off of a live line
In electrical engineering, power drag inside, electricity is divided into weak electricity, strong electricity, and low voltage, high voltage, ultra-high voltage. But inside the weak electricity, there are strong electricity and even high voltage electricity, such as television sets, switching power supply, LED light power supply, weak to a few volts of electricity, high to more than 10,000 volts. High voltage inside the low voltage power and weak power, because the control system control are low voltage control high pressure, weak control low voltage, is to operate safely.
If you simply use a multimeter to measure the energised line on and off, I am not in favour! You can use an electric pen to measure the presence or absence of electricity, or, after the power is disconnected, use an ohm stop to measure the line good or bad.
Electrician is a high-risk industry, there will be times when you need to measure data, and without electricity there is no way to measure the actual data voltage, current. And waveforms. The charged measurement and belongs to the charged operation, although there are labour insurance products, insulated gloves, insulated shoes, the guy with the work is genuinely inconvenient, friends say the work is difficult to do it!
As for how to use the multimeter, you can read the manual, on Baidu, guys answered very well I will not repeat, I would like to express the notes on the measurement of the bandwidth how to work more safely and more safely use the multimeter.
First, the charged measurement of weak electricity
Measurement should not first blindly to measure, review the circuit of weak and strong power, choose a good gear, measuring DC, AC24V voltage below the basic no danger, but do not touch the utility, and equipment in the high-voltage part, as well as large capacitors.
Measurement of low-voltage equipment in the high-voltage, the best way is to first power off, discharge (including capacitors) and then the meter pen to choose a good gear, placed in a good measurement point, and then send the power to read the measurement data, the digital multimeter with a memory button, you can press the memory button, so it will be safer.
When measuring voltage with multimeter in factory, voltage is not necessarily line is through, no voltage line is definitely not.
Due to the charged measurement, there are transformers and motors in the line, there is power on the breakpoint, and there is power under the breakpoint, the power on the breakpoint is the power supply power, and the power under the breakpoint is the power of the other phase through the winding or coil string over the power, so we must pay attention to this phenomenon. So with a multimeter with power to measure the line on and off is not measured! For utility power, should be single-phase power, the fire line is broken, there is no power, but the zero line is broken, will measure the phenomenon of power without voltage.
To sum up, with a multimeter with power to measure the line through is not correct, get it wrong, not their own winding into it, the best way is to use the ohm block after the power failure, or use a rocking meter to measure the line through is more accurate.
