A capacitor is an electronic device that allows you to accumulate and then give off an electrical discharge. The main characteristic of an element is its capacitance, which determines the dependence of charge on voltage.
Classification of capacitors
Different technologies for the production of devices allow the production of different types of devices. Air capacitors are products in which the dielectric is air. The advantages of this type of devices are ease of manufacture. They are intended for mechanical regulation of capacity and are designed for mechanical constant influences. The disadvantages of this type of devices include instability, poor reliability, dependence on humidity and temperature of the environment, large dimensions, relatively low electrical strength, which is limited by the breakdown between air platinum, and low capacitance.
There are paper types of capacitors in which paper impregnated with transformer oil acts as a dielectric. These devices have a highreliability and electrical strength. At high voltage, they have a fairly high capacitance and low current leakage.
Many capacitors for power plants are produced according to the paper principle. To do this, two plates are put together, between which paper is placed. Then the device is rolled up and placed in a jar, which is filled with transformer oil, and then sealed. The disadvantages of the device include heavy weight, high self-inductance and resistance.
Electrolytic types of capacitors have a dielectric, presented in the form of an oxide layer that appears on the surface of the active metal (usually aluminum). The device is produced by placing a tape made of active metal into an electrolyte, on the surface of which a film of strong oxide is formed, which makes it possible to insulate the metal.
The main feature of electrolytic types of capacitors is the presence of polarity, at one value of which they hold the rated voltage, and when it changes, they quickly collapse. This occurs as a result of chemical processes that occur between the electrolyte and the metal of the plate. The oxide film gradually cracks and breaks down.
However, if the correct polarity is observed, microcracks are quickly covered with new oxide. The advantages of these devices include high capacitance, the disadvantages are polarity, loss of properties, rapid wear, high internal inductance.
Viewscapacitors and their applications
There are also devices in which mica acts as a dielectric, they are used in various electrical installations. Since mica is able to store energy on its own, these types of capacitors have high capacitance and electrical strength. Disadvantages include parameter instability, non-linearity, high cost, and capacitance-current dependence.
In addition, ceramic types of capacitors, film, Teflon, polypropylene and other devices have found application.
