Dielectric absorption
Encyclopedia
Dielectric absorption is the name given to the effect by which a capacitor
that has been charged for a long time discharges only incompletely when briefly discharged. Although an ideal capacitor would remain at zero volts after being discharged, real capacitors will develop a small voltage, a phenomenon that is also called soakage or battery
action. For some dielectric
s, such as many polymer
films, the resulting volt
age may be less than 1-2% of the original voltage, but it can be as much as 15 - 25% for electrolytic capacitor
s or supercapacitor
s. In order to prevent shocks most very large capacitors are shipped with shorting wires that need to be removed before they are used.
See permittivity
and Types of capacitor#Dielectric absorption (soakage).
Capacitor
A capacitor is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric ; for example, one common construction consists of metal foils separated...
that has been charged for a long time discharges only incompletely when briefly discharged. Although an ideal capacitor would remain at zero volts after being discharged, real capacitors will develop a small voltage, a phenomenon that is also called soakage or battery
Battery (electricity)
An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy. Since the invention of the first battery in 1800 by Alessandro Volta and especially since the technically improved Daniell cell in 1836, batteries have become a common power...
action. For some dielectric
Dielectric
A dielectric is an electrical insulator that can be polarized by an applied electric field. When a dielectric is placed in an electric field, electric charges do not flow through the material, as in a conductor, but only slightly shift from their average equilibrium positions causing dielectric...
s, such as many polymer
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
films, the resulting volt
Volt
The volt is the SI derived unit for electric potential, electric potential difference, and electromotive force. The volt is named in honor of the Italian physicist Alessandro Volta , who invented the voltaic pile, possibly the first chemical battery.- Definition :A single volt is defined as the...
age may be less than 1-2% of the original voltage, but it can be as much as 15 - 25% for electrolytic capacitor
Electrolytic capacitor
An electrolytic capacitor is a type of capacitor that uses an electrolyte, an ionic conducting liquid, as one of its plates, to achieve a larger capacitance per unit volume than other types. They are often referred to in electronics usage simply as "electrolytics"...
s or supercapacitor
Supercapacitor
An electric double-layer capacitor , also known as supercapacitor, supercondenser, electrochemical double layer capacitor, or ultracapacitor, is an electrochemical capacitor with relatively high energy density. Their energy density is typically hundreds of times greater than conventional...
s. In order to prevent shocks most very large capacitors are shipped with shorting wires that need to be removed before they are used.
See permittivity
Permittivity
In electromagnetism, absolute permittivity is the measure of the resistance that is encountered when forming an electric field in a medium. In other words, permittivity is a measure of how an electric field affects, and is affected by, a dielectric medium. The permittivity of a medium describes how...
and Types of capacitor#Dielectric absorption (soakage).