In electrolytic capacitors (electrolytic capacitors ), the cathode consists of a conductive liquid, the electrolyte, in contrast to normal capacitors. The dielectric is formed by an extremely thin oxide layer, which is located on the anode. In addition, there are developments with polymer electrolytes made of conductive polymers.
Elcaps are polarized compensators and are used to smooth current peaks, to compensate for voltage fluctuations, to screen the rectified AC voltage in power supplies and as current buffers for electronic circuits. Their capacitance can reach values of up to 100 mF. Supercapacitors have even larger capacitances. The values of electrolytic capacitors are specified in the E series according to DINIEC 63. According to this, there are the standard values E6, E12 and E24.
The use in power supplies is characterized by the mains frequency of 50 Hz or 60 Hz and the low internal resistance of the rectifier. In these circuits, the electrolytic capacitor is located behind the rectifier or thyristor and smoothes the semi-sinusoidal DC voltage. The capacitance of the electrolytic capacitor can be calculated from the mains frequency, the internal resistance, the supply power and the degree of smoothing.
Characteristic values of electrolytic capacitors
In addition to the capacitance and dielectric strength, which can range from a few volts to about 500 V, the internal resistance, the Equivalent Series Resistance( ESR) of the electrolytic capacitor is also important, since this determines the discharge current and the rate of change of the electrolytic capacitor. For example, electrolytic capacitors can certainly handle load currents of 50 A/µs with minimal voltage fluctuations. Such load requirements can occur motherboards, memory chips or graphics processors.
As polarized capacitors, electrolytic capacitors must be connected with the anode to the positive voltage and the cathode to the negative voltage. The connecting wires are marked; that of the anode is longer.