Almost every man knows what is a multimeter, which is an indispensable electrical measuring instrument. A complex device performs many functions, therefore it can replace several other tools, thereby saving money on their purchase and space in the workshop.
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How to choose a multimeter
A multimeter is a versatile instrument that combines the capabilities of an ohmmeter, voltmeter, and ammeter, often offered as a clamp meter. It works by direct connection to the electric circle according to the principle of comparing the incoming signal with a standard.
Multimeter selection based on answering several questions:
- for what purposes the device is bought (for home use, intensive work in production or for various studies);
- how important is the accuracy of the data obtained;
- Are additional features needed?
- where the device will be used (indoors or will be carried).
The meter can be of various types: professional and household, digital and analog, with and without additional functions, stationary and portable (portable).
Like any other technique, measuring device professional differs from domestic in several characteristics:
- higher accuracy;
- the ability to work in intensive mode for a long time;
- durability and reliability;
- durable body;
- higher price.
For the user, the type of operation of the device is important - digital or analog. Analog is obsolete types of multimeters, whose work is based on a magnetoelectric needle (its sensitivity determines the accuracy and measurement range of the device). In some modes of operation, the meter has a non-linear scale and requires polarity when connected.
The digital model is easier to use, so even a person who has not previously held the device in his hands can master it. This is a more accurate and compact device, all measurements take place automatically. Most often, it has a number of additional functions, and its bit depth ranges from 2.5 to 5 or more.
Both analog and digital multimeter can be mains powered (stationary model) or portable (small self-powered device - from batteries or accumulators).
Varieties of multimeters are considered to be all digital scopmeters and voltmeters.
Which model is better to buy
Is it better to choose a digital or pointer meter? Analog Model - Simplest: Simple frame and design, it inexpensive. But there are other differences that are worth exploring when choosing quality multimeter.
Influence of polarity when connecting. For modern digital devices, the polarity of the applied signal - the measurement will always be performed correctly, only with reverse polarity, a minus sign will appear on the display. The pointer device needs to comply with the connection rules, otherwise there will be no results.
Accuracy of measurements. Several factors affect the accuracy of an analog device:
- position corps relative to the ground;
- influence of an external magnetic field;
- user experience.
Digital multimeters (professional and household) are always accurate, and the data obtained is displayed on large display and are presented in a form understandable to the operator.
Resistance to mechanical damage. Arrow models in their design have suspended frames, the fastening of which (thin hairs) breaks during vibrations, strong shocks and shakes. Modern digital meters are enclosed in shock-resistant corpsto protect the instrument from damage.
The ability to track the dynamics of indicators. The analog instrument will show the change signal instantaneously, while the digital one needs some time to digitize the data and display it on the screen.
Functions and possibilities. Analog multimeters do not have additional features, while digital devices can additionally determine the temperature, capacitance of capacitors, select the measurement range, calculate the ratio between data as a percentage, etc. (depending on the model).
Effect of battery charge on measurement accuracy. Any digital (even compact) multimeter will work properly until signal "replace battery" on the display. The pointer model, when the power source is discharged, knocks down the zero settings and distorts the data, so the user should always correct the settings before starting work.
Parameters for device selection
When using for home use or when choosing a model for intensive work, it is worth studying the technical characteristics and capabilities of the multimeter.
Energy security option. The instructions for each device indicate the class of the meter:
- CAT I - the device is designed to work with low-voltage power lines;
- CAT II - the unit is used when working with local electric lines;
- CAT III - the device is used to work with distribution lines in the premises;
- CAT ІV - meter intended for work with distribution lines outdoors.
Bit depth, that is, the range and number of full bits. The indicator "3.5" means that one digit from the limited range and three from the range 0 ... 9 will be displayed on the device monitor. This characteristic does not affect the measurement accuracy.
Multimeter accuracy is especially important in industrial environments. It depends on the parameters of the current, calibration, protection against external interference, model.
The most common and desired functions of the meter are:
- continuity of diodes (possible with sound and/or light signal);
- measurement of voltage, current strength, frequency, resistance (with alternating and direct current, including large values);
- capacitance measurement;
- temperature determination;
- checking bipolar transistors;
- definition of inductance;
- generating a simple test signal (harmonic or impulse).
The following functions are additionally possible: blocking and display backlight, integrated memory, indication of overload or low battery, auto power off to save resources, automatic setting of measurement limits, protection of input circuits and tester, Hold button. Some models are equipped with two screens: the first is digital with data updates every 4 seconds, the second is an arrow one, capable of recording up to 20 changes per second.
When choosing a meter, you should pay attention to the quality of the probe wires, material corps (it must be resistant to moisture, dust and shock), the presence of an additional case for carrying and storing.
What is the difference between a multimeter and a tester
In addition to multimeters, there are voltage testers, which are used to determine the presence of voltage in the electrical circuit and to measure it. The unit is characterized by a simpler design, quick response, the ability to work in any conditions and ease of operation.
Previously, arrow testers were used, reminiscent of screwdrivers. Today they are:
- neon - this is a common model, which consists of a handle and a contactor, a signal light;
- LED - have a similar principle of operation with neon devices, but additionally allow you to determine the phase and zero cables, conduct non-contact analysis;
- versatile or multifunctional.
The last type of meter has the ability to work in 3 modes (sound, non-contact and contact), determines voltage, resistance, current strength. The device has a wide handle with mode switches and special protection of the working part in the form of a cap. Such digital tester can be considered a simplified multimeter, but with a limited set of functions. A multimeter is also sometimes called a tester.
Rating of the best multimeters for home and car
On the domestic market there are a large number of meters of various types for any needs. AT top The top 10 devices included products from Mastech, APPA, Fluke, Resanta, Elitech, CEM. Their models differ in the scope of use, the number of measurement modes, functions, cost, appearance. Let's spend a little multimeter comparison in 4 categories: budget devices, for home use, for motorists and for professional use.
Budget appliances
MASTECH M830B is a budget household multimeter with an accuracy of 0.5%. Allows you to determine the physical parameters of the electrical circuit, the gain of transistors, ring semiconductor diodes. The device is equipped with probes, the power source is a 9V krone battery.
PROCONNECT DT-182 is a compact and accurate device (error 0.5-1.8% depending on the parameter) with a wide range of functions. Suitable for testing batteries, measuring strength, current resistance. The model lacks the auto-shutoff function, but has an affordable price. Production: China.
RESANTA DT830B meter intended for home use or for diagnosing vehicle problems. It will allow you to determine the performance of transistors and diodes, the value of resistance, current, voltage. The multimeter has a switch for 20 positions, overload protection, can work both indoors and outdoors.
The best household models
UNI-T UT33A is a device with automatic selection of measurement limits, auto-shutdown for 30 minutes of inactivity and a panel for checking the health of transistors. The power source is two AAA 1.5V batteries.
CEM DT-912 has a compact and ergonomic framewhich is not afraid of moisture and mechanical damage. Research data are displayed on the LCD display, equipped with a backlight. The measurement range is adjusted manually and automatically, it is possible to remember the last readings.
Testers for motorists
FLUKE 28-II - positioned as a professional multimeter for car with an affordable price. It has a wide range of functions - basic and additional (memory, thermometer, screen backlight, low-pass filter), soft probes. Frame made of materials resistant to mechanical damage, moisture, dust, high and low temperatures.
ELITECH MM 100 is a successful model for troubleshooting electrical systems in cars and self-propelled machinery. Allows you to ring the circuit, check semiconductor diodes, determine the physical parameters of the current. The device has a sound buzzer, a small monitor, special overload protection.
Devices for professionals
Professional meters are distinguished by high-quality wires, high speed and accuracy, an informative screen and a large number of features. In addition, they are enclosed in shockproof and hermetic corps, can almost always be used even in extreme conditions (too high or low temperatures, noise, vibration). Therefore, their high price fully justified - the multimeter will serve for years.
CEM DT-9979 is a multifunctional meter in sealed corpsresistant to mechanical damage. In addition to the standard functions of the multimeter_ has a number of additional ones, including: auto power off, display backlight, memory, the ability to plot graphs and various types of analysis, output the received data to a PC. The device has a high degree of protection (IP67), stand-emphasis for comfortable work, modern design.
KEYSIGHT 3458A is a device with a resolution of 8.5 digits, 110 modes of operation, a wide range of functions and analytical and mathematical capabilities, various research methods. Suitable for highly specialized professionals who need exceptionally accurate and timely data.
CEM DT-3219 is a compact electronic multimeter with a set of 7 functions, large LCD screen, graphic scale, indication, automatic shutdown. Easy to use, with an ergonomic housing protected from moisture, dust and mechanical damage.
