Clarification of information about the cause of the breakdown of electronic and household appliances always begins with measuring their parameters and checking each part. For this purpose, various devices are used that can measure amperage, resistance and voltage. You can use separate devices: for example, a voltmeter or ammeter, but it is better to have a comprehensive instrument for measuring such a multimeter on hand. How to measure the current strength with a multimeter and what kind of device is it?
On sale there are two main types of multimeters: analog and digital. Each of them has its own advantages and disadvantages. The analog model is quite cheap, reliable and durable to use, but such a tool gives a large error in the measurement of parameters. In addition, it is rather inconvenient to use: it will be difficult for beginners to navigate in the measurements due to different gradations on the indicator scale for each individual model (analogous devices made in Asian countries are especially affected by this ailment). For those who care about accuracy in measurements, who don’t want to delve into the instructions for a long time, to understand what the indicators on the device are responsible for, and to whom the issue of price is not as important as usability, you should take care to buy a digital version of the device.
As already mentioned, a multimeter combines several devices at the same time. One way to use it is to measure current. It will help to determine this parameter of the electric network in the battery, outlet, power supply unit of a personal computer or charger. With the help of such a device, it is possible to measure the current strength in an electric circuit with direct or alternating current.
How to measure the current strength with a multimeter? To understand the principle of operation of the device, you first need to deal with such a question as the operation of its indicators and connectors. It should be understood why they are needed and how they are generally used during measurements. In any model of the multimeter, you can find two separate terminals and several sockets for plugs. Nests can be from 2 to 4, on devices of an old design there are several more. The black output is used to measure the “minus” parameter of the network, red, respectively, for the “plus”.
Before starting work, we fix the black probe in the socket marked “-”, red - “+”. If there are additional sockets, then they are usually designed for measuring current strength in different ranges: for example, a connector marked "mA" for measuring current strength up to 1 ampere, with a mark "A" for checking this parameter in the range from 1 to 10 A etc.
Also, the device may have several switches. Their purpose is similar in principle to working with the jacks for the probes - they are needed to change the tested ranges of voltage and resistance.
How is a multimeter used to measure current?
In order to get an answer to the question of how to measure the current strength with a multimeter (for those who have forgotten the physics lessons, we recall that this parameter of the electric network is measured in Amperes), you first need to install the measuring probes in the corresponding connectors. Next, we select the network that we plan to measure, that is, a network with direct or alternating current. In analog models, for this purpose, we set the toggle switch to the required position, and on the digital device, press the corresponding button to select the desired network. Before checking, you also need to know the voltage of the tested electrical device. This parameter is fixed on the multimeter using the same switch or key. After the initial preparation, the verification itself follows: we touch with the probes the plus and minus conclusions of the device under test. With the correct settings of the multimeter, information about the current strength in the network can be seen on the indicator or on the dial of the device for verification.
When measuring current, there are certain nuances regarding parameter measurements for certain devices, devices and electrical circuits.
Battery Current Measurement
Before measuring the battery current with a multimeter, we set the maximum permissible values of the checked parameters on the device itself. Then, in parallel, connect the tester leads to the device under test: black - to the "minus", red - to the "plus". Verification time is minimal. When the expected information appears on the screen panel of the device, the probes must be immediately turned off, because as a result of this procedure a short circuit occurs, which very negatively affects the further operation of the power source.
Measuring current in an electrical outlet
The first important rule of how to measure the strength of the current with a multimeter in the outlet: you can not check the operation of the outlet directly. If you connect the measuring device without load electronic devices, then you simply burn it. That is, an electric device is inserted between them in the “multimeter-outlet” circuit: for example, a multimeter-bulb-outlet. After the correct serial connection, we measure the current strength in the circuit. It is not worth delaying the test for a long period, it is desirable that the procedure in time be no longer than 10-15 seconds.
Checking the current in the charger
It is easy and simple to measure the current strength of the charger with a multimeter . To do this, when measuring, in order not to burn the multimeter, again we set the maximum values of the parameter to be checked on the measuring device. We also translate the device into operation with DC networks. Then we connect the device to the charger in the mode of checking the current strength: we connect one of the probes to the wire going to the charger at the place of the gap. In order not to damage the power source and tester, we take measurements as quickly as possible.
Current measurement in alternating current circuits
It is recommended to measure the AC current with a multimeter as follows:
- The multimeter itself is connected through a break in the circuit.
- We set the tester to the maximum verification range of the desired parameter.
- Then we connect the black probe to the "negative" wire.
- After a short time touch the red probe to the positive cable or terminal.
- After reading the current parameters, immediately turn off the red probe.
It is worth noting the fact that not all testers for complex testing can work in AC networks. If this parameter is important for you to check, then before buying, be sure to find out whether the purchased multimeter can work with networks of this type. Because not all devices allow you to measure the current strength in the circuit with a multimeter.
Checking the current strength in the power supplies of electrical appliances
You can also measure the current strength of the power supply with a multimeter through an open circuit. After connecting the probes to the tester sockets, we connect the black probe to the negative terminal of the power supply, and the “plus” to a specially made place for a network break, that is, to the “positive” cable coming from the power supply. After receiving the information, turn off the multimeter.
General information on checking the current strength in electric circuits using a multimeter
The main difference between measuring the current strength in a circuit with a multimeter and measuring resistance and voltage lies in the way the test device is connected: it is connected to the electric circuit not in a parallel but in a serial way. That is, the device is connected in a specially created place for a cable break. If you want to use the device to test a multiphase circuit (for example, a three-phase circuit), then such a gap is made for each individual phase.
Measurement of parameters with a multimeter in networks with constant current
How to measure direct current strength with a multimeter? Measuring the current strength in these networks is practically no different from checking the same parameter in alternating current networks. It is important to choose the type of network to be checked on the multimeter, and the rest of the steps are identical to the procedures for checking the current strength for networks of the type described above.
Some useful tips for working with a multimeter
- When working with an analog type device during measurements, when accurate results are important, it is advisable to keep the device in a horizontal position: if the multimeter is upright or folding, then the information on the indicator may be distorted and untruthful.
- To obtain reliable information, the instrument must be calibrated before each use. It is very simple to make: just connect the probes to each other and the potentiometer.
- With unknown parameters of the device under test, it is worth setting the initial values on the multimeter to the maximum acceptable level so as not to burn the tester.
- If you have to check devices with small parts, then you should purchase an additional set of terminals with thin, needle probes. If there are no thin probes at hand, you can use auxiliary means at hand: for example, a straightened paper clip to which the probe is screwed with a wire.
How to measure the current strength with a multimeter? To perform such a simple task, you must have a working device and a certain amount of knowledge. After all, each item has its own characteristics of measurement. The multimeter is very easy to use and does not pose any threat to life. But still it is not recommended to give it to children.