Dielectric Absorption (soakage)
Dielectric absorption is the name given to the effect by which a capacitor, which 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 coming from time-delayed dipole discharging, a phenomenon that is also called dielectric relaxation, "soakage" or "battery action".
|Type of capacitor||Dielectric Absorption|
|Class-1 ceramic capacitors, NP0||0.3 to 0.6%|
|Class-2 ceramic capacitors, X7R||2.0 to 2.5%|
In many applications of capacitors dielectric absorption is not a problem but in some applications, such as long-time-constant integrators, sample-and-hold circuits, switched-capacitor analog-to-digital converters, and very low-distortion filters, it is important that the capacitor does not recover a residual charge after full discharge, and capacitors with low absorption are specified. The voltage at the terminals generated by the dielectric absorption may in some cases possibly cause problems in the function of an electronic circuit or can be a safety risk to personnel. In order to prevent shocks, most very large capacitors are shipped with shorting wires that need to be removed before they are used.
Famous quotes containing the word absorption:
“These philosophers dwell on the inevitability and unchangeableness of laws, on the power of temperament and constitution, the three goon, or qualities, and the circumstances, or birth and affinity. The end is an immense consolation; eternal absorption in Brahma.”
—Henry David Thoreau (18171862)