Basic Outline of Digital Multimeter
Basic outline of a digital multimeter:
A digital multimeter (GMM) is an electronic instrument to be used in electrical measurements. It can have many special functions, but the main function is to make measurements of voltage, resistance and current. Digital multimeters, as modern multi-purpose electronic measuring instruments, are mainly used in the field of physical, electrical and electronic measurements. Basic outline of digital multimeter
Resolution, Digits, Words
Basic Outline of Digital Multimeter Resolution refers to how good a meter is at measuring results. By knowing the resolution of a meter, you can tell if you can see small changes in the measured signal. For example, if a digital multimeter has a resolution of 1mV over a 4V range, you can see a small change of 1mV (1/1000 of a volt) when measuring a 1V signal.
If you were measuring a length of less than 1/4 inch (or 1 mm), you certainly wouldn't use a ruler with *smaller* units of inches (or centimetres). If the temperature is 98.6°F, it's useless to measure it with a thermometer that has only integer markings. You need a thermometer with a resolution of 0.1°F. Humidity Sensor Probes , , Stainless Steel Heaters PT100 Sensors , , Cast Aluminium Heaters , Heating Coils Fluid Solenoid Valves
The number of digits and words is what is used to describe the resolution of the meter. Digital multi-meters are categorised by the number of bits and words they can display.
A 3½-digit meter can display three full numeric digits from 0 to 9, and one half-digit (1 only or no display). A 3½-digit meter can achieve a resolution of 1999 words. A 4½-digit meter can achieve a resolution of 19999 words. Basic Outline of a Digital Multimeter
It is better to describe the resolution of a digital multimeter in terms of words than in terms of bits, and the resolution of a 3½-digit digital meter has been increased to 3200 or 4000 words. Basic Outline of a Digital Multimeter
A 3200 word digital meter provides better resolution for some measurements. For example, with a 1999-word meter, you can't measure voltages greater than 200 V and still get to 0.1 V. A 3200-word digital meter can measure voltages up to 320 V and still get to 0.1 V. When the measured voltage is higher than 320 V and you want to get to a resolution of 0.1 V, you'll want to use a 20,000-word meter, which is a bit more expensive.
Accuracy
Accuracy is the maximum permissible error under a specific usage environment. In other words, accuracy is used to indicate
how close the measured value of a digital multi-meter is to the actual value of the signal being measured.
For digital multimeters, accuracy is usually expressed as a percentage of the reading. For example, a 1% reading accuracy means that when the digital multi-meter display is 100.0V, the actual voltage may be between 99.0V and 101.0V.
There may be specific values added to the basic accuracy in the detailed instructions. It means the number of words to be added for the transformation of the rightmost end of the display. In the previous example, the accuracy may be labelled ±(1%+2). Thus, if the GMM reads 100.0V, the actual voltage will be between 98.8V and 101.2V.
The accuracy of an analogue meter is based on the error at full scale, not on the displayed reading. Typical accuracy of an analogue meter is ±2% or ±3% of full scale. Typical basic accuracies for digital multi-meters are between ±(0.7%+1) and ±(0.1%+1) of the reading, or better.
