What is a multimeter? Purpose and principle of operation of the tool - Setafi

A multimeter is a handy tool that can be used to measure voltage, resistance, and current. It consists of a mechanism enclosed in a housing, as well as test leads with probes. The device, types and selection criteria for this tool are described in detail in the article.

Description of the multimeter

If we explain in simple terms what a multimeter is, we can say that it is a universal device that is used to measure 3 indicators:

• voltage in Volts;
• current strength in Amperes;
• resistance in ohms.

In fact, it performs the functions of 3 instruments - an ammeter, an ohmmeter and a voltmeter. It is used to diagnose electrical networks in the field of electrical engineering and electronics.

Previously, analog instruments were common. But now we can say about the multimeter that in most cases it is a digital device. It features high measurement accuracy, convenient operation and reliability.

The device consists of several elements:

• screen (display), which displays the results of measurements;
• buttons for a particular option;
• a knob that allows you to select one value for the current measurement, for example, Volt;
• input connectors - allow you to connect one or more test leads.

If you study what a multimeter is for, first of all, to measure the main indicators of an electrical circuit. This allows you to solve several problems at once, including diagnostics, debugging and network repair.

For testing, special test leads are used. They are flexible, under a layer of insulation, have 2 colors:

• red is connected to the positive contact;
• black - to the negative.

They play the role of conductors that connect the tested objects with the device. And each wire has a tip with a probe. It is used to test the circuit.

Types of multimeters

It is clear that the multimeter measures the main parameters of the current (strength, resistance and voltage). This allows you to determine possible errors and causes of failure in the circuit. Moreover, it is possible to carry out measuring work using different devices:

• analog;
• digital.

The former are more affordable, although larger in size. A small microammeter is placed in the case, which creates its own electromagnetic field. As a result, it affects the needle (as in the case of a compass), which deviates along the scale and shows a certain value during measurement.

This device has several advantages:

• affordable;
• not so sensitive to interference when measuring voltage, as well as resistance;
• if the needle oscillates, you can reliably judge the dynamics of the signal (in this case, the digital device will only show the average value).

Although there are also quite a few disadvantages:

• large measurement error;
• large dimensions;
• must be set to zero before starting;
• when held on weight or on a vibrating surface, the measurement accuracy decreases;
• individual values ​​have to be calculated independently.

If we talk about what a digital multimeter is used for, we can say that it has exactly the same purpose as an analog one. but the principle of action here is different. The device has an analog-to-digital converter, as well as a display on which indicators are displayed. Therefore, there is no need to follow the arrow - just read the reading from the screen.

This tool has several important advantages:

• very simple measurement procedure;
• the accuracy of the results is noticeably higher;
• accuracy does not depend on the height at which the device is held;
• even if you connect the polarity incorrectly, it will not deteriorate;
• The tool is compact and light in weight.

It is clear what the digital multimeter is intended for. It measures 3 important indicators of the power grid, just like analog models. Moreover, the error is small, there is no need to look closely at the arrow. But this tool also has disadvantages:

• costs much more;
• practically does not work in the cold;
• if the battery runs out, the screen becomes dim;
• if the housing is heated, large errors may occur.

The principle of operation of a digital instrument multimeter differs from that of an analog instrument, but in general, their scope and purpose are the same.

How to choose a multimeter

When choosing a specific model, you need to pay attention to several technical characteristics: Among them, the safety class, measurement error, dimensions, and others are of great importance. The main criteria are as follows:

1. Electrical safety class - according to this indicator, tools are divided into those used in low-voltage, local circuits and distribution systems.
2. Weight and dimensions - it is better to choose compact digital instruments that take up a minimum of space and are also very light in weight.
3. Measurement error - in everyday life it is possible within 2.5%. If applied in the professional field, the error should be a maximum of 1.0%. And it also happens that you have to work with very sensitive equipment. Then the error rate should not exceed 0.5%.
4. Resistance level - for use at home, including for repairing your own car, 2 MΩ is enough. If it is supposed to work, for example, with large cables, the indicator should be much higher - up to 60 MΩ.
5. The presence of illumination is especially important when repairing in the dark, as well as in hard-to-reach places.

Also, many devices are equipped with additional functions. Some of them have a temperature gauge. Others have software installed that allows you to connect to your computer via Bluetooth. It is quite obvious why a multimeter is needed in such cases. The obtained data is transferred to a PC for further processing and calculations.

Another useful option is the “Hold” standby mode, when the device saves the last data on the screen, if at the moment it cannot be seen due to the contact of the probes and terminals. Some devices also have water protection, which allows you to work even in water.

From this review it is clear that a multimeter is a device for measuring the main parameters of a network. Today, analog models are already outdated. Although they are cheaper, the measurement accuracy is usually lower. Therefore, for everyday work, it is better to purchase a digital device.