As we benefit more and more from the major discoveries of the digital era, it was also time for a change as far as voltage measurements are concerned. Thus, more accurate measurements are possible with the help of a digital voltmeter, and this is the reason why this device is an electrician’s favorite tool nowadays.
Understanding the concept
Voltmeters are instruments that measure voltage, that is, the electrical potential difference – either gain or loss – between two points in an electric circuit submitted to the test. When they were first invented in the 1800s, voltmeters were called galvanometers and from the technical point of view, were, in fact, designed to measure current and not voltage. However, the early models were not quite accurate even if they were functional at this empirical level. They need to be taken as mere attempts of understanding the effect of passing a current through a wire. There was still a long way to the digital voltmeter as we have it today.
Types of Voltmeters
Generally, there are two types of voltmeters used for voltage measurements: analog voltmeters and digital voltmeters. Of course, they are made in different styles and function either as panel permanently mounted instruments, portable instruments or handheld devices. Different brands have tried to create the most functional devices with the highest efficiency and quality standards, so there are lots of models on the market with different characteristics: panel type, different size and volume, mounting possibilities, best price etc.
How a Digital Voltmeter Works
Basically, digital voltmeters function as analog ones, except that the results of the measurements will be shown on a digital display, such as a LED or a LCD.
Also called DVM’s, these instruments function based on an integrating converter. This way, the signal is transformed from analog into digital, directly related to the magnitude of the signal. The common units of the scale shown on the digital display are volts. Depending on the type of the voltmeter, in order to obtain more accurate results, other subunits of volt can be displayed.
It is very common to use digital voltmeters in order to monitor a unit. It can be a generator, for instance.
One of the greatest advantages is that with digital voltmeters you may measure both alternating current and direct current.
Generally speaking, voltmeter accuracy can be damaged by some factors, such as temperature and voltage variations. In order to make sure it displays the most accurate results, these instruments need to be calibrated against a voltage standard after a certain period. It is also known that digital voltmeters have input amplifiers with 10 megohms input resistance which is a constant, no matter the range of measurements.
Digital voltmeters have proven to be more functional than the analog ones as they have higher resolution and input resistance, and read values faster and more accurate, regardless of the waveform.