This guide covers the application of polar, non-solid aluminum electrolytic capacitors, which are those aluminum electrolytic capacitors featuring a wet, aqueous electrolyte with separator membranes such as cellulosic papers between two aluminum foils.
Other types of aluminum electrolytic capacitors not cov-ered include the obsolete wet types without separator mem-branes, “hybrid” aluminum electrolytic capacitors containing both polymer and liquid electrolyte components and sol-id-polymer electrolytic capacitors.
Other component materials include a paper separator that Fig-2 holds electrolyte in place and another aluminum foil that func-tions as a draw-out electrode coming into contact with the true cathode (electrolyte). In general, an aluminum electrolytic capacitor is asymmetrical in structure and polarized.
These are available for momentary-duty AC applications like motor starting and voltage-reversing applications, but the high DF of aluminum electrolytic capacitors – from 2% to 150% – causes excess heating and short life in most AC applications.
Aluminum electrolytic capacitors can generally withstand extreme overvoltage transients of limited energy. Application of overvoltage more than about 50 V beyond the capacitor’s surge voltage rating causes high leakage current and a constant-voltage operating mode quite like the reverse conduction of a zener diode.
In general, an aluminum electrolytic capacitor is asymmetrical in structure and polarized. The other capacitor type known as a bi-polar (non-polar) comprises the anodic aluminum foils for both electrodes.