Several tips for using digital multimeter well
Regarding the use skills of digital multimeters, it is very helpful to master these skills when using digital multimeters correctly, including judging whether the line or device is live or not, distinguishing whether the power supply line is live or neutral, digital multimeter looking for cable breakpoints, measuring ups frequency of the power supply, etc.
Several skills of using digital multimeter
1. Determine whether the circuit or device is charged or not
The AC voltage block of the digital multimeter is very sensitive, even if there is a small induced voltage around it, it can be displayed.
According to this feature, it can be used as a test pen.
The usage is as follows: turn the multimeter to the AC20V block, the black test lead is suspended, and the red test lead is in contact with the route or device on the side. At this time, the multimeter will display. There are different displays), indicating that the line or device is charged, if the display is zero or very small, indicating that the line or device is not charged.
2. Distinguish whether the power supply line is a live line or a neutral line
The first method: You can use the above method to judge: the larger number is the live line, and the smaller number is the zero line. This method requires contact with the line or device being measured.
Second method: No contact with the line or device being measured is required. Turn the multimeter to the AC2V block, the black test pen is hanging in the air, hold the red test pen and gently slide the pen tip along the line, if the meter shows a few volts at this time, it indicates that the line is the live wire.
If the display is only a few tenths of a volt or even less. It means that the line is the zero line. This judgment method does not directly contact the line. Not only safe but also convenient and fast.
3. Find breakpoints in cables
When there is a breakpoint in the cable, the traditional method is to use a multimeter to electrically block the breakpoint of the cable section by section, which not only wastes time, but also damages the insulation of the cable to a large extent. Using the inductive characteristics of the digital multimeter can quickly find the disconnection point of the cable.
First use the electric block to determine which cable core wire is broken. Then connect one end of the open-circuited core wire to the AC220V power supply, then turn the multimeter to the position of the AC2V block, the black test pen is suspended, and hold the red test pen to gently slide the tip of the pen along the line. Volts or a few tenths of a volt (varies from cable to cable), if you move to a certain position, the display on the watch suddenly drops a lot, write down this position: in general. The breakpoint is between 10 and 20 cm in front of this position.
This method can also find the breaking point of resistance wires such as faulty electric blankets.
4. Measure the frequency of the ups power supply
For UPS power supply. The stability of the voltage at its output is an important parameter, as is the frequency of its output.
However, it cannot be measured directly with the frequency block of the digital multimeter, because the voltage that the frequency block can withstand is very low. Only a few volts.
A 220V/6V or 220V/4V step-down transformer can be connected to the output end of the UPS power supply to reduce the voltage without changing the frequency of the power supply, and then connect the frequency block to the output of the transformer to measure the frequency of the UPS power supply .
