As technology expands the demand for more elaborate and more accurate instruments increases and produces new developments in instrument design and application. The digital multimeter is the best outcome of this advanced technology. Today, these devices are considered to be among the most essential equipment required by technicians, electricians, engineers, and inspection professionals. To use these instruments intelligently, you have to know their advantages and disadvantages.
Advantages of digital multimeters
Digital multimeter has many benefits for users. Some of them are listed below:
Measurement of current, voltage, and resistance
The digital multimeter is a multi-purpose, hassle-free, all-in-one, and one of the most useful electrical equipment used for testing and measuring any type of electrical device. It helps get to the root cause faster.
A digital multimeter allows by itself the measurement of DC voltage, AC voltage, DC current, AC current, and resistance. So, it offers the combined functionality of an ohmmeter, a voltmeter, and an ammeter.
Less reading errors
Using a multimeter is one of the most basic skills in electronics but reading a multimeter is not difficult. A digital multimeter displays the quantity measured as a number; it eliminates observational, parallax, and approximation errors.
Effective working principle
DMM has a simple working principle. First, the information from the analog input signal passes through the various analog signal conversion circuits which convert the measured quantity to a dc voltage equivalent. Then the analog to digital converter converts the dc value to digital form and the display unit displays the value. The digital multimeter is made up of the following three basic elements:
- Signal conditioning
- Analog-to-digital (A/D) conversation
- Numeric digital display
Measurement of quantities with different ranges can be possible. The digital multimeter consists of an LCD, and a knob to select various ranges of electrical characteristics. All the available measuring modes can be selected manually. It can be used for testing batteries, household wiring, electric motors, and power supplies.
Various measuring functions
In addition to basic measuring functions, most models are provided with features such as a diode test function and a continuity buzzer. Some recent products feature the measurement of frequency and capacitor capacity.
Data hold function
Some have added functions of maximum and minimum value hold and relative value measurement as well as data hold and range hold functions are also available.
In addition to the visual display, the output from the digital multimeters can also be used to interface with some other equipment. The output of these instruments can be directly fed to a computer for further analysis and use.
Manual and auto range functions
Advanced digital multimeters have both manual range and auto range modes. In the auto range mode, the meter selects the range with the best resolution. In the manual range mode, you override auto range and select the range yourself.
Accuracy refers to the degree of closeness or conformity to the true value of the quantity under measurement. A Digital multimeter offers high measurement accuracy. Higher accuracy (1% or less) compared with an analog multimeter (approximately 3%).
Durable and portable
Digital multimeter displays have no moving parts. This makes them free from wear and shock failures. The meter has protection against undesired input range. Hence meter can be protected from overload or fault or misuse.
Multimeters are compact, durable, and last for a longer period. Portable size makes it is easy to carry anywhere. Besides, when operated following the instruction manual, it does not require any particular maintenance.
High input impedance
To prevent the measured object from being influenced during voltage measurement, you should use a measurement device with an extremely high input impedance. Digital multimeters have a high input impedance.
No zero adjustment and auto polarity
Unlike analog multimeter, zero adjustments are not required. The auto polarity function prevents problems from connecting the meter to the test circuit with the wrong polarity.
Advanced digital multimeters have energy-saving features. The automatic power-off function is always enabled as a default setting. If no control key is pressed within approximately 15 min, the instrument switches off automatically. If necessary, the automatic power-off function can be turned off.
Disadvantages of digital multimeters
Digital multimeter has some drawbacks. Some of them are listed below.
Low battery causes reading difficulty
Digital multimeters are battery-powered. When the battery is low, the display will be dim and making it difficult to read. You should replace the battery as soon as the low battery indicator appears.
DMM has a voltage limitation. Failing to do this will cause damage to the equipment and also cause personal injury.
A digital multimeter is more expensive than an analog model. Due to improvements in integrated technology, prices are going down.
Pocket type limitations
Pocket-type digital multimeters normally cannot be used for the measurement of current for safety reasons.
In case of fluctuations or transients, it can record an error.
Warming of the meter during its use can change its properties leading to errors in the measured value. You should prevent the instrument from being heated due to exposure to direct sunlight. This is the only way to guarantee the instrument will function perfectly and have a long service life.
Dirt or moisture
Dirt or moisture in the terminals can affect readings. You should always keep it clean.
The battery could be dangerous
The battery acid (electrolyte) is highly alkaline and electrically conductive. Risk of acid burn! If the battery acid comes into contact with your skin or clothing, thoroughly rinse the areas affected immediately with plenty of water.
The instrument is not explosion-proof. It cannot be used in explosive atmospheres. When there is rain or other precipitation there is a risk of electric shock.
To maintain the specified accuracy of the measurement results, manufacturers recommend calibrating the instrument once a year.