Look around yourself, and you can see tons of appliances. From a basic bulb to advanced laptops, everything is running on current. To know the working principle or trace any electrical fault, you need to measure current.
Luckily, the current can be easily measured with a multimeter. Now the question arises, how to measure current using a multimeter. Before measuring current, you must know about current. Then we can proceed to question how to measure DC current using a multimeter. And later study how to measure AC current using a multimeter.
What is current?
Current is the flow of electrons from high potential to low potential space. This flow of electrons is known as current. It is this flow of electrons that impacts voltage and resistances.
Difference between AC and DC
First, it's essential to know that the flow of current can be different. Understanding the difference will help solve our question of how to measure AC current using a multimeter. Current can be either AC current or DC depending on the direction and mode of the source. AC, as the name suggests, Alternating current changes its direction periodically while DC flows in a single direction.
DC supply is primarily popular in low voltage, low current applications such as batteries, cell phones, electronic circuits, and laptops. Portable devices also use DC current because you can store power in DC form only. However, the AC power supply is widely used due to its ability to transmit electricity over long distances with minimal losses.
What is a multimeter?
The electrical properties need to be monitored for our safety and research. For that purpose, an electronic testing tool multimeter is used. A Multimeter can measure multiple electrical properties such as voltage, current, capacitance, and resistance. Hence it is also known as volt-ohm-milliammeter (VOM).
A general multimeter has many components which function in order to get the task done. I will elaborate how these components are to be used, how they work and get the task done. The components of the multimeter that I will discuss are display, keypad, dial and probe.
The display of the digital multimeter is a screen at the top which shows the electronic measurement. Depending on which type of multimeter you would be using a digital one or an analogue the display might be different.
The analogue shows the measurement on an analogue scale with a pointed needle. The digital scale shows reading in discrete digits. In digital display we have a number of counts like 6000, 4000 and 2000. The backlight display is also a plus feature in good quality multimeters.
The keypad in a multimeter consists of a numerical dial. It is used to input numerical values inside the multimeter. Some digital multimeters also have a hold button to measure fluctuating current values.
The multimeter measures multiple electrical values but you have to select the option first. The dial alternates between these quantities. The dial is usually rotatable and can vary accordingly. Through the dial we can alternate between different categories.
The probes in a multimeter are connected to the device that is under observation. The probes are flexible elongated wires. They have clamps at the end which are then connected to the device. There are different standards of probes like CAT-III and CAT-II.
CAT-II quality Test leads
CAT-II standard test leads can measure up to 600 volts easily and can be used on single phase distribution easily.
CAT-III quality Test leads
CAT-II standard test leads can measure up to 1000 volts easily with a resistance of 2 ohms.CAT-III standard is perfect for three phase industrial distribution easily.
Digital multimeter vs. Analogue multimeter
The multimeter can be either digital or analog, depending on its display. Choosing an analog multimeter or a digital multimeter can depend on the output you want to achieve. Though the digital multimeter gives discrete digital figures, it is more accurate.
- A digital multimeter has a numeric value directly being displayed on the screen. You don't have to analyze the measurement.
- In addition to this, the analog multimeter needs to be analyzed. The display of an analog consists of a scale that is distributed according to the least count. A needle points to the measurement on the screen displaying the current, voltage, or resistance measured. The pointer moves over the scale to give the reading. Furthermore, the analog multimeter is also known as VOM since it measures voltage, current, and resistance.
In the end, it depends on individual preference and availability to choose from the best multimeters to measure current-voltage and other electrical values.
How is the ammeter different from a general multimeter?
Let's first look at what an ammeter is. Ammeter is a device that measures the electrical quantity current. Due to the limitation of the ammeter to just measure current, a multimeter can measure multiple entities. Hence a multimeter was formed, which measured not only current but other quantities as well.
Clamp multimeter is not like a general digital multimeter. It has C.T type clamps at the end of the multimeter. These clamps measure current without using probes while probes are also available to measure voltage.
Luckily you don't have to plug or unplug live circuits for current measurement while using multimeters. A Hinged jaw is integrated into the multimeter which measures current directly without disconnecting.
How does the clamp multimeter work?
The clamp multimeter consists of a ferrite iron beneath plastic clamps to function. The hard jaws are constructed in such a way that they detect and measure magnetic fields being generated by the current.
A clip type current transformer is used in it to measure electrical values. A standard clamp multimeter senses the magnetic flux around the cables and converts into numeric values.
Measuring current with clamp multimeter
Clamp multimeters are preferred to measure current of high level. A multimeter does not have the capability to measure 10 A of current for more than 60 minutes without causing internal damage.
In addition to this, To repair electronic circuits you need best calibrated multimeters which can measure precise values. Whereas a clamp meter can measure current up to 0.1A at least to a maximum current flow of 600 A depending upon different clamp meters.
Before you scratch your head and ask how to measure DC current using a multimeter, decide whether your multimeter can tolerate the current of the device being measured.
Here I'm sharing with you some tips and tricks that you should keep in mind. It will help you in deciding which multimeter you should get yourself to measure current.
Different multimeters can measure a variety of parameters. Depending on which specific multimeter you are looking for a typical range can be from 1 milliamp to 600 amperes.
To check the accuracy of a multimeter, always make sure to do a survey test first. Take a known supply and measure the current of that known source. If the multimeter gives the same expected result then you are good to go.
You should always calibrate your multimeter before you start measurement. You would calibrate the instrument by checking the meter’s accuracy against an already calibrated multimeter.
Moreover, you could simply set the multimeter to highest resistance and touch the test probes together. If the multimeter gives value zero after pressing the calibration knob you are good to go.
Safety measures should be taken to avoid any big mishaps. Thus, always check the multimeter for physical damage before testing.
What do the symbols mean on the multimeter?
The symbols on the multimeter represent the electrical parameters such as A is ampere, V is volt and a horse shoe symbol means resistance.
Is my multimeter safe to be used?
Inspect your multimeter thoroughly first and then proceed. If you are not sure about using the multimeter, consult an electrician or a professional first.
When should my multimeter be calibrated?
A multimeter should be calibrated once a year and verified to be checked for calibration. If you have a fluke multimeter for current measurement then you can also send your multimeter to fluke labs.
I hope now that you have gone through this article it has saved your time. Now you can easily answer how to measure the DC using a multimeter and how to measure AC current using a multimeter. So, you are now ready to measure AC/DC current, get the best budget multimeter for yourself and start your journey.