Multimeter: All you need to know

25-May-2016 16:53 pm 0

Digital multimeters are here to make your life easy. The meters can be used to calculate 3 electrical parameters of current, voltage, and resistance. Knowing how to efficiently use digital multimeter can enable you to measure accurate readings.

Knowing how to use a DMM can enable the best to be gained from them – the most accurate readings and also knowing the limitations of the readings. It also allows you to use some tricks of the trade which can help you measure parameters that may not normally be known about.

fluke-27-ii-digital-multimeter-fluke-digital-multimeter-0

Fluke 27 II Digital Multimeter

 

Digital Multimeter- Multimeters are two kinds. Analog Multimeter and Digital multimeter. Analog is a microammeter that has a pointer and is preferred over digital if the current is highly fluctuating and the pattern of fluctuation is of importance. A digital multimeter gives the low range values of Current(AC/DC),  voltage (Digital Voltmeter) and resistance. Some multimeters also provide the  additional measurements like Capacitance, Temperature, Frequency, Transistor test -he(may not be that accurate). The Range of a digital multimeter can auto-shift so that most significant digits are shown. The multimeter price varies according to its purpose from a ₹100 to ₹50000.

  • When making a voltage measurement the probes from the digital multimeter are placed across the points where the voltage is to be measured(in parallel).
  • Measuring current is done by breaking the circuit and placing the digital multimeter acting as a current meter in a circuit(in series).
  • For Measuring resistance, the item to be tested should not be affected by other components within the circuit. So, it is removed from the circuit and measured separately.

Multimeter provides more accuracy but the range is limited for the safety of the user whereas the clamp meter provides safety but the accuracy is limited to around 95 % which reduces with lower currents.

The troubleshooting for Multimeter includes changing its battery and if once opened, locate and replacing the fuse wire.

Factors to consider before buying a Digital Multimeter-

Auto-Range feature– If your multimeter has this feature then the range automatically changes to give the most meaningful reading in the best resolution for the instrument. If the reading exceeds the range then the instrument will show OL(overload). Then, you need to change the instruments range to suit your readings.

Display- Display is measured in the no. of digits that can be displayed on the screen. A digital multimeter is usually 3½ (3 places that display values from 0 to 9 and the last one displays either 0 or 1) or 4½.

Resolution(Price increases with increase in resolution for the smallest range)
-Smallest change in an input signal that produces a change in the output signal is the resolution of that device. Resolution depends on the range you have set for the instrument. The resolution is 1V on 1000V range. For 300 mV range, the resolution is 0.1 mV.

Accuracy (Price increases with increase in accuracy)                                         –Accuracy is expressed as ±(% of reading + number of least
significant digit (LSD). For example, for a 1kV (0.1%±1), the readings vary from 9989V to 1011V.

True RMS Converter

If you are more concerned with power measurements, you would require the true RMS values. RMS value is different from the average value. True RMS converter only comes with high priced instruments.

 

Summary
Article Name
Multimeter: All you need to know
Description
This article explains everything that you need to know about multimetrs. It also helps you buy a multimeter.
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