Datasheet

Aluminium Electrolytic Capacitors
4
Fig.2 shows a cross
section of the winding.
If two capacitors are connected in series, the total capacitance results from the relationship
C
G
=C
A
*C
K
/(C
A
+C
K
).
If C
A
<< C
K
it follows C
G
C
A.
( aspired normal case)
This means the anode capacitance determines the capacitance of the whole capacitor ( the cathode foil decreases
the capacitance only somewhat). To accomplish that, highly etched cathode foils are necessary.
Nonpolarized electrolytic capacitors use the same foil for anode and cathode ( C
A
= C
K
) Therefore the capacitance
of these capacitors are given by C
G
= 0,5 * C
A
.
It is obvious that a nonpolarized electrolytic capacitor needs two times the space of a polarized capacitor.
2. Different types of foil
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Anode foil
Oxide layer
Cathode foil
Electrolyte
Paper
C
A
C
K
Fig. 2
high - voltage anode foil
low - voltage anode foil
cathode foil
etched surface
etched and formed surface
solid aluminium core
etched and formed surface
solid aluminium core
solid aluminium core