Almost every man knows, what a multimeter is.which is an indispensable electrical measuring device. The complex device performs many functions, so it is able to replace several other tools, thereby saving money on their purchase and space in the workshop.
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How to choose a multimeter
Multimeter is a universal device, which combines the possibilities of ohmmeter, voltmeter and ammeter, often offered as a clamp meter. It works by direct connection to an electrical circuit on the principle of comparing the incoming signal with a reference.
Choosing a multimeter is based on answering several questions:
- for what purpose the instrument is purchased (for home use, intensive work in production, or for various studies);
- How important is the accuracy of the data obtained;
- Whether additional features are needed;
- where the device will be used (indoors or portable).
The meter comes in various types: professional and household, digital and analog, with and without additional functions, stationary and portable (portable).
Just like any other technique, meter professional differs from household in several ways:
- higher accuracy;
- ability to work in an intensive mode for a long time;
- durability and reliability;
- rugged housing;
- higher price.
The type of operation of the device - digital or analog - matters for the user. Analogue meters are outdated types of multimeterswhose operation is based on a magnetoelectric pointer (its sensitivity determines the accuracy and measuring range of the device).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 never held the device in his hands before can master it. It is a more accurate and compact device, all measurements are automatic. Most often it has a number of additional functions, and its digit capacity varies from 2.5 to 5 or more.
Both the analog and digital multimeter can operate from the mains (stationary model) or be portable (a small device with self-contained power - from batteries or rechargeable batteries).
All digital scopmeters and voltmeters are considered varieties of multimeters.
What is the best model to buy
A digital or an arrow meter is better to choose? The analog model is the simplest: a simple case and design, it is inexpensive. But there are other differences that are worth investigating when choosing a quality multimeter.
The effect of polarity when connected. For modern digital devices does not matter the polarity of the applied signal - the measurement will always be performed correctly, only if the polarity is reversed, the display will show a minus sign. The pointer device needs to comply with the rules of connection, otherwise there will be no results.
Accuracy of measurements. The accuracy of the analog device is affected by several factors:
- position housing in relation to the ground;
- The influence of an external magnetic field;
- user experience.
Digital multimeters (professional and consumer multimeters) are always accurate and the data is displayed on the large display and presented in an easy to understand manner for the operator.
Resistant to mechanical damage. Arrow models in their design have a suspended frame, the fastening of which (thin hairs) tears when vibrations, strong shocks and shaking. Modern digital meters are encased in a shockproof housingswhich protects the device from damage.
Ability to track the dynamics of indicators. An analog meter will show the change in of the signal instantaneous, while the digital one needs some time to digitize the data and display it on the screen.
Features and capabilities. Analog multimeters have no additional features, while digital devices can additionally determine temperature, capacitance of capacitors, select the measuring range, calculate the ratio between data in percentages, etc. (depending on the model).
The effect of battery power on measurement accuracy. Any digital (even compact) multimeter Any digital multimeter (even a compact one) will function correctly until a signal "replace battery" signal appears on the display. An arrow model will knock out the zero setting and distort the data when the power supply is depleted, so the user should always adjust the settings before starting work.
Parameters for selecting the instrument
When using it for home use or selecting a model for heavy-duty work, it is worth examining the specifications and capabilities of the multimeter.
The energy safety parameter. The manual for each device specifies the class of the meter:
- CAT І - the unit is designed to work with low-voltage power lines;
- САТ ІІ - the unit is used when working with local electric lines;
- САТ ІІІ - the unit is used to work with distribution lines in the premises;
- CAT IV - meter is designed for working with distribution lines outside the premises.
Range, i.e. the range and number of full discharges. The indicator "3.5" means that one digit from the limited range and three from the range 0...9 will be displayed. This characteristic does not affect the accuracy of measurements.
The accuracy of a multimeter is especially important in industrial environments. It depends on current parameters, calibration, protection against external interference, model.
The most common and necessary functions of the meter are:
- diode dialling (possible with sound and/or light signal);
- measurement of voltage, current, frequency, resistance (AC and DC, including large values);
- capacity measurement;
- temperature determination;
- Bipolar transistors testing;
- determination of inductance;
- Generating a simple test test signal (harmonic or pulsed).
The following functions are also possible in addition: locking and display backlight, integrated memory, overload or low battery indication, auto power off to save resources, automatic setting of measurement limits, protection of input circuits and tester, Hold button. Some models have two screens: the first digital with data update every 4 seconds, the second - an arrow capable of fixing up to 20 changes per second.
Choosing a meter, it is worth paying attention to the quality of the probe wires, the material housing (it must be resistant to moisture, dust and shock), availability of an additional carrying and storage case.
What is the difference between a multimeter and a tester
In addition to multimeters, there are on sale voltage testersIn addition to multimeters there are voltage testers which are used to determine the presence of voltage in electrical circuits and to measure voltage. The unit is characterized by a simpler design, speed of operation, the ability to work in all conditions, and ease of operation.
In the past, the use was made of a dial tester, which resembled a screwdriver. Today they come in a variety of models:
- neon - this is a common model, which consists of a handle and contactor, a signal lamp;
- LEDs - have the same principle of operation as the neon devices, but additionally allow you to determine the phase and neutral cables, conduct a non-contact analysis;
- universal or multifunctional.
The last type of meter has the ability to work in 3 modes (audio, non-contact and contact), determines the voltage, resistance, current. The device has a wide handle with mode switches and a 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. Multimeter is also sometimes called a tester.
Rating of the best multimeters for home and car
On the domestic market there is a large number of various types of meters for all needs. В top 10 best devices got products of companies Mastech, APPA, Fluke, Resanta, Elitech, CEM. Their models differ from each other by the scope of use, the number of measurement modes, functions, cost, appearance. Let's make a short comparison of multimeters in 4 categories: devices for the budget, for home, for motorists and for professional use.
Budgetary devices
MASTECH M830B is a budget multimeter with an accuracy of 0,5%. It allows you to determine the physical parameters of the electrical circuit, the gain of transistors, to test the semiconductor diodes. The meter is equipped with probes, the power supply is a 9V Krone battery.
The PROCONNECT DT-182 is a compact and precise meter (error 0.5-1.8% depending on the parameter) with a wide range of functions. Suitable for testing of batteries, measuring power, resistance of current. Model does not have auto shut-off function but is reasonably priced. Production: China.
PESANTA DT830B. designed for for home use or for car troubleshooting. It will determine the performance of transistors and diodes, the value of resistance, current and voltage. Multimeter has a switch for 20 positions, overload protection, can work both indoors and outdoors.
Best residential models
UNI-T UT33A is a device with automatic selection of measurement limits, automatic shutdown in case of inactivity for 30 minutes and a panel to check the working order of transistors. Two 1.5 V AAA batteries serve as a power source.
CEM DT-912 has a compact and ergonomic housingwhich is not afraid of moisture and mechanical damage. Research data is displayed on an LCD display equipped with backlight. Range of measurements can be adjusted manually and automatically, there is a possibility of storing the last reading.
Testers for Motorists
FLUKE 28-II - positioned as a professional multimeter for cars with an affordable price. Has a wide range of functions - basic and additional (memory, thermometer, backlighting screen, low-pass filter), soft probes. Case 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 mechanisms. Allows to test the electrical circuits, check the semiconductor diodes, determine the physical parameters of current. The device has an audible buzzer, a small monitor, and special overload protection.
Devices for Professionals
Professional meters are distinguished by high-quality wires, high speed and accuracy, informative screen and a large number of possibilities. They are also built in shock-resistant and waterproof housingsThey can practically always be used even under extreme conditions (too high or too low temperatures, noise, vibrations). Therefore, their high price is fully justified - the multimeter will serve for years.
CEM DT-9979 - Multifunctional meter in a sealed case caseresistant to mechanical damage. In addition to the standard functions of the multimeter_ has a number of additional functions, including: auto power off, display backlightmemory, the possibility of constructing graphs and various types of analysis, the output of the data obtained to a PC. The device has a high degree of protection (IP67), stand-support for convenient operation, modern design.
KEYSIGHT 3458A has 8.5 digits resolution, 110 operation modes, wide range of analytical and mathematical functions and various research methods. Suitable for highly specialized professionals who need extremely 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 shut-off. Easy to use, with an ergonomic housing, protected from moisture, dust and mechanical damage.
