6 точок за вибір а мультиметр
1. Надійність: Особливо під суворі умови, надійність є більше важливий ніж будь-коли.
2. Безпека: The main consideration in the design of the digital multimeter has passed the independent test of the certification laboratory, and printed symbols of the test laboratories such as UL, CSA, and VDE.
3. Resolution: Resolution is also called sensitivity, which refers to the smallest quantification unit of the the digital multimeter's measurement results, that is, that is, subtle changes in the measured signal can be seen. For example: Припускаючи that the resolution of the digital multimeter in the 4V range is 1mV, then when measuring a signal of 1V, you can see a slight change of 1mV. The resolution of a digital мультиметр is usually indicated in digits or words.
The resolution of the digital multimeter is a very important goal. Just like you want to measure the length of less than 1 mm, you will definitely not use a ruler whose smallest unit is meters; perhaps the temperature is 98.6 degrees F, then it is measured with a thermometer that only has integer symbols. No use, you need a thermometer with a resolution of {{}}.1 degree F.
For a 3.5-digit meter, the last three digits can display three full digits from 0 to 9, and the first digit can only display one and a half digits (1 or no display), that is, the 3.5-digit digital table can reach 1999 characters resolution; a 4.5-digit digital multimeter can reach a resolution of 19999 words. It is better to describe the resolution of a digital table in words than in digits. The resolution of today's 3.5-digit multimeters has advanced to 3200 or 4000 counts. A 3200 count DMM provides very good resolution for some measurements. For example, with a 1999-word meter, when measuring a voltage greater than 200V, it is impossible for you to display 0.1V. However, the 3200-digit digital multimeter can still flash to 0.1V when measuring the voltage of 320 volts. When the measured voltage is higher than 320V and the resolution of 0.1V is to be achieved, a more expensive 20,000-word digital multimeter should be used.
4. Accuracy: refers to the maximum allowable error in a specific application environment. In other words, accuracy is used to indicate how close the measured value of the digital multimeter is to the actual value of the signal being measured. For digital multimeters, accuracy is usually expressed as a percentage of reading. For example, 1 percent of reading accuracy means that when the digital multimeter displays ten 0.0V, the actual voltage may be between 99.0V and ten 1.0V. In the detailed instructions, there may be a specific value plus the final sub-precision, which means the number of words to be added to replace the rightmost end of the display. In the previous example, the precision might be marked as ±(1 percent plus 2). Therefore, assuming that the reading of the multimeter is ten 0.0V, the actual voltage will be between 98.8V and ten 1.2V. The accuracy of the analog meter (or pointer multimeter) is calculated by the error of the full scale, not by the displayed reading. The typical accuracy of an analog multimeter is ±2 percent or ±3 percent of full scale. The typical basic accuracy of a digital multimeter is between ±(0.7 percent plus 1) and ±(0.1 percent plus 1) of reading, or even higher.
5. Ohm rule: The ohm rule shows the relationship between voltage, current and resistance. Using Ohm's rule, any circuit voltage, current, and resistance can be calculated: Voltage=Current × Resistance. So you only need to know any two values in the formula to calculate the third value. A digital multimeter uses the ohm rule to measure and display resistance, current or voltage.
6. Digital and analog pointer display: In terms of accuracy and resolution, digital display has excellent advantages, and the measured value can be displayed with three or more digits. The analog pointer is slightly inferior in accuracy and resolution, and we usually read by estimating the position of the pointer. DMMs have a bar graph that shows changes and trends in the signal just like a pointer, but it is more durable and less prone to damage.
