Causes of damage to digital multimeters
In most cases, the damage of the digital multimeter is caused by the wrong measurement gear. For example, when measuring AC mains, the measurement gear is selected to be placed on the electric block. In this case, once the pen contacts the mains, the internal components of the multimeter will be damaged instantly. . Therefore, be sure to check whether the measurement gear is correct before using the multimeter to measure. After use, set the measurement selection to AC 750V or DC 1000V, so that no matter what parameter is wrongly measured in the next measurement, it will not cause damage to the digital multimeter.
The damage of some digital multimeters is caused by the measured voltage and current exceeding the range. For example, when measuring the mains power in the AC 20V range, it is easy to cause damage to the AC amplifier circuit of the digital multimeter, so that the multimeter loses the AC measurement function. When measuring DC voltage, the measured voltage exceeds the measurement range, which is also likely to cause circuit failure in the meter. When measuring the current, if the actual current value exceeds the range, generally only the fuse in the multimeter will be blown, and no other damage will be caused. Therefore, if you do not know the approximate range of the measured voltage when measuring the voltage parameters, you should first set the measurement gear to the highest gear, and then change the gear measurement to obtain a more accurate value by measuring the value. If the voltage value to be measured is far beyond the maximum range that the multimeter can measure, a high-resistance measurement lead should be provided. Such as detecting the second anode high voltage and focusing high voltage of black and white color TV.
The upper limit range of DC voltage of most digital multimeters is 1000V, so the maximum voltage value when measuring DC voltage is below 1000V, which generally will not damage the multimeter. If it exceeds 1000V, it is very likely to cause damage to the multimeter. However, the upper limit of the measurable voltage may be different for different digital multimeters. If the measured voltage exceeds the range, the method of reducing the resistance of the resistor can be used to measure it. In addition, when measuring 400-1000V DC high voltage, the test leads must be in good contact with the measurement place, and there should be no jitter. Otherwise, in addition to causing damage to the multimeter and making the measurement inaccurate, the multimeter can be used in serious cases. show
