You do not know the three major uses of digital multimeters in daily applications
Digital multimeter, a multi-purpose electronic measuring instrument, generally includes functions such as ammeter, voltmeter, ohmmeter, etc., sometimes also called multimeter, multimeter, multimeter, or triple meter.
Digital multimeters are available as portable units for basic fault diagnosis, as well as those placed on a workbench, and some have a resolution of seven or eight digits.
A digital multimeter (DMM) is an electronic instrument used in electrical measurements. It can have many special functions, but the main function is to measure voltage, resistance and current. Digital multimeter, as a modern multi-purpose electronic measuring instrument, is mainly used in physical, electrical, electronic and other measurement fields.
Types of DMM Protection Circuits
1. Automatic recovery protection. Some watch circuitry, when an overload is detected, protects the watch until the condition no longer exists. After the overload is removed, the DMM automatically returns to normal operation. Usually used to protect the resistive function from voltage overload.
2. There is no automatic recovery function. Some meters will protect the meter after detecting overload, but will not automatically recover until the user takes corresponding measures, such as replacing the resistance, to resume use.
Safety features of digital multimeters
1. Fuse current input protection
2. Use a high-energy fuse (600 volts or higher)
3. High voltage protection in resistive mode (500V or higher)
4. Voltage transient protection (6000 volts or higher)
5. Safely designed test leads, safety handles, etc.
6. Independent safety certification
The routine use of digital multimeters in daily work is well known, so do you know of other unexpected uses? The following is shared by Xi'an Antai Testing Equipment Maintenance Center:
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 digital 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. The multimeter will have 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 line is live or neutral
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 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 means 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 AC20V 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 500 cm in front of this position.
This method can also find the breaking point of resistance wires such as faulty electric blankets.
