Pointer multimeter usage considerations
A good habit of using a multimeter is to look at whether the gear position is correct before each measurement. If you develop such a habit, the probability of burning the meter will be greatly reduced.
The range should be selected so that the pointer is indicated near two-thirds of the full scale, and the reading is more accurate. If you do not know the magnitude of the measured voltage and current, you should select a large number of range blocks, and then readjust the range according to the size of the reading to make the reading accurate.
When measuring the resistance, the range must be re-zeroed after changing the range gear, so that the reading can be accurate. If the zero position is not adjusted, the battery voltage in the meter is insufficient, and the battery should be replaced.
When measuring the resistance online, the power supply should be cut off for operation, and it should also be noted whether other components form a parallel circuit with the measured resistor, and if necessary, the resistance can be welded from one end of the circuit and then measured. For circuits with electrolytic capacitors, the capacitors are discharged before measuring.
When using a multimeter, develop the habit of not touching the metal part of the pen with your hand to prevent electric shock accidents. At the same time, when measuring resistance, such as touching the metal part of the pen with a hand, it will affect the reading.
When measuring DC voltage, the red pen is connected to "+" and the black pen is connected to "-" to prevent the counter from being deflected in the opposite direction and damaging the needle. In the case of not knowing the positive and negative polarity, you can first dial a large number of range blocks, quickly touch the measured point with the pen, and observe the direction of the pointer swing to determine the correct polarity. In particular, the mA block or electrical block should not be misused to measure the voltage, otherwise the instrument will burn out.
When measuring current, it is absolutely not possible to straddle two gauge pens on the power supply to avoid burning the gauge head. General multimeters can only measure DC current, not AC current.
After the meter is used up, the range switch should be placed in the highest voltage gear, and for the multimeter with short or disconnected gear, it should be placed in the corresponding gear to prevent others from damaging the instrument without paying attention to it.
So in daily work, many people will have some wrong methods when using multimeters, the following is for everyone to take stock, have you also done this?
1. Replace the fuse of the original multimeter with a cheap fuse. If your digital multimeter (DMM) meets the electrical safety standards it identifies, the fuse should be a fuse with special safety that can be quickly disconnected before a serious overload occurs for instrument and personal safety. When you need to replace the fuses of a digital multimeter, be sure to use fuses that comply with safety specifications and are allowed to be used.
2. Use a piece of metal wire or metal sheet to replace the multimeter fuse. This may seem like a quick fix when you can't find a surplus fuse on hand, but such a fuse can pose a serious safety issue.
3. Use inappropriate tools for the work being carried out. It is important to use a digital multimeter that is appropriate for the work to be done. First, to ensure that the digital multimeter (or other test tool) has the correct CAT (electrical safety) level suitable for each test occasion carried out, even throughout the day to switch to a different digital multimeter; second, to ensure that the maximum continuous operating voltage of the digital multimeter meets the actual test needs.
4. When using a multimeter to measure a live line, the line should be cut off as much as possible. If you need to measure live lines, be sure to use the correct insulation tools, wear ear protectors, safety glasses, arc-proof masks, and insulating gloves, remove your watch or other jewelry, stand on an insulating mat, and wear flame-retardant overalls (instead of your usual overalls).
5. Ignore the test line. The test line is an important aspect of ensuring the safety of digital multimeters. Ensure that the test lines also have a CAT electrical safety rating suitable for the appropriate operation, and use test wires with double insulation (silicone material), protective input connectors, finger guards and non-slip surfaces.
6, with both hands at the same time to perform the test, must not be like this! When measuring live lines, there is a trick to remember: keep one hand in your pocket. This makes it difficult to form a closed circuit that runs through the chest and heart. Hanging or lowering the multimeter as much as possible and avoiding holding the multimeter in your hand minimizes the risk of exposure to transient voltages. Of course, in higher-risk measurements, additional measures should be taken to reduce hazards and arc flashover risks. These additional measures include the use of protective equipment specified in the National Electrical Code, such as protective gloves, protective clothing and goggles, to provide arc protection.