What is a Capacitor and What does it do?
A capacitor is an electronic component whose function is to store electric charges. It is made of two conductors that are separated by a dielectric material. When connected to a power source, these plates accumulate electric charges.
How are Capacitors Classified?
The types of capacitors available range from a very small delicate trimming capacitors using an oscillator or radio circuits, up to large power metal-can type capacitors used in high voltage power correction and smoothing circuits.
According to structures, capacitors can be classified into the following:
- Fixed Capacitors
- Variable Capacitors
- Trimmer Capacitors
The capacitors are classified into two types as :
A polarized capacitor is an important component of the electronic circuit and often termed as an electrolytic capacitor. These capacitors are used to achieve high capacitive density.
Unpolarized capacitors are preferred over polarized capacitors because it doesn’t get destroyed by reverse voltage and can be used in pure AC circuits. They also find applications in DC circuits as they don’t have positive and negative ends. The frequency of the unpolarized capacitor is high and the leakage current is low.
Types of Capacitors
Capacitors are categorized into 2 mechanical groups. Fixed Capacitors consisting of fixed capacitance value and variable capacitance with variable capacitance value. Beneath are a brief description of various capacitor types and their properties.
- Ceramic Capacitors
- Film Capacitors
- Power Film Capacitors
- Electrolytic Capacitors
A ceramic capacitor is a fixed capacitor consisting of a metal and two alternating layers of ceramic. Here metals act as an electrode and ceramic metal serves as a dielectric. An electric behaviour of capacitors can be classified into two classes of stability. That is Class 1 and Class 2. Ceramic capacitors are available in various styles and shapes that are used in unique applications. Some of them include high voltage ceramic power capacitor, multilayer ceramic capacitors, and Ceramic EMI suppression capacitors.
Film capacitors or plastic capacitor is a capacitor which consists of an insulating plastic film as the dielectric. Electrodes of plastic capacitors are made up of zinc applied on both sides of a plastic firm, appearing as a metalized film capacitors. In metalized film capacitors, when there is a breakdown of dielectric between electrodes, there won’t be any damage caused to the components as metalized construction produces a wound capacitor comprising of the large capacitance value.
Power Film Capacitors
Construction techniques and materials that are used in power film capacitors are similar to that of ordinary film capacitor. Polypropylene film is used as a dielectric in a capacitor.
In electrolytic capacitor metallic anode coated with oxidized layer used as a dielectric. These capacitors are polarized. Electrolytic capacitors are categorized based on their dielectric.
- Aluminum electrolytic capacitors – aluminum oxide ( dielectric).
- Tantalum electrolytic capacitors – tantalum pentoxide (dielectric).
- Niobium electrolytic capacitors – niobium pentoxide ( dielectric).
What are Common Capacitors?
Capacitors are mainly divided into two mechanical groups:
- Fixed capacitors
- Variable capacitors
Some common capacitors and their names are mentioned in the table below.
|Aluminium, tantalum, and niobium electrolytic capacitors|
|Film and paper capacitors|
|Silver mica, glass, silicon, air-gap, and vacuum capacitors|