What is electrolytic capacitor? What are its characteristics?

Do you know what a capacitor is and what it is for? The capacitor is one of the most well-known components, but few people really know how a capacitor works and what the main characteristics of a capacitor are. Knowing this, the World of Electrical answers these and other questions related to capacitors, especially about the electrolytic capacitor. So come on guys!

Capacitors: What are they?
Capacitors are considered reactive elements, which react to the passage of electric current due to the accumulation of electrical charges, that is, capacitors have the capacity to store electrostatic energy.

A basic capacitor model has two conductive plates also known as armatures, which are separated by a dielectric material. In other words, they are two metallic materials, and between them, there is another material that is insulating. Capacitors are specified in Farads (F) and their submultiples (microfarad, nanofarad, and picofarad).

Do you know how a capacitor works and what is it for?
The basic structure of a capacitor.

Capacitors: Working principle
Now that we know what a capacitor is made of, we can understand its working principle, which is relatively simple! By applying a potential difference between the conductor plates of the capacitor, where one plate stores positive charges and the other store’s negative charges. Capacitors can also operate in both direct and alternating current depending on the type of capacitor.

When the capacitor is charging or discharging it has a variable value of electric current, however, due to the fact that there is a dielectric material between the capacitor plates, this energy does not pass from one plate to another, so that this energy is stored.

It can be said that the main function of the capacitor is to accumulate electrical charges in a circuit, to later discharge these same charges. It is important to highlight that the charges are accumulated equally, that is, both negative charges and positive charges have the same value in the module.

A curiosity in relation to the dielectric material used in the capacitor is that it usually gives rise to the name of the capacitor, for example, polyester capacitor, ceramic capacitor, mica capacitor and others.

Electrolytic capacitor: What is it?
There are several types of capacitors, such as polyester capacitors, ceramic capacitors, SMD capacitors and electrolytic capacitors. Electrolytic capacitors differ from the others because of the thickness of their dielectric, which is very small. In addition, most capacitors have fixed polarity, with the exception of special electrolytic capacitors.

What is the basic structure of a capacitor?
Comparison of the dielectric material of the capacitors.

In the most common types of capacitors, the same materials are used for the armatures, which can be tantalum (Ta), aluminum (Al), niobium (Nb), in addition to others that allow this characteristic. Currently, the most used capacitors are aluminum and tantalum. Because of tantalum, the capacitors made by this material are smaller, when compared with others of the same capacitance. Below is an image that can better illustrate.

What are the characteristics and applications of a capacitor?
Capacitors of the same capacitance.

Electrolytic capacitors have the capacitance indicated on the component housing, therefore their value in Farads and submultiples. In case you do not know the capacitors present leakage current, because when a direct voltage is applied to the capacitor a small current flows. This is because the dielectric of the capacitor is not a perfect insulator, in addition to other factors that can also contribute to this leakage of currents such as humidity and the characteristics of the enclosure.

Another important point of the capacitors is that when they are operating in the alternating current they have an equivalent resistance, resulting in a lag between current and voltage, in addition to dissipating electrical power.

When making a project we must take into account several characteristics of a capacitor, such as:

Rated voltage
Surge Voltage
Operating Temperature Range
Working Voltage
Ripple chain
Lifetime and Failure Rate
After seeing some characteristics of the capacitors it is possible to see that it is not just choosing the capacitance and nominal voltage of the capacitor! Therefore, when making any project, the responsible person must be aware of the characteristics of the electrolytic capacitors, because the influence of external factors interferes with the capacitor’s functioning and useful life.

If you are interested in learning even more about capacitors, below is a video from the Mundo da Elétrica channel that explains in detail how a capacitor works, what are the types of capacitors and where the capacitors are used, it is very worth watching!