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Posted on 22 June 2019

Temperature Influence on Series Capacitance

 

The capacitance of an electrolytic capacitor is not a constant quantity that retains its value under all operating conditions. Temperature has a considerable effect on capacitance. With decreasing temperature, the viscosity of the electrolyte increases, thus reducing its conductivity.

Figure 1: Heat transport in a aluminum electrolytic
capacitor

 

 

 

 

 

 

As a general rule, the characteristic curves showing capacitance as a function of temperature are steeper for lower rated voltage and increasing anode surface roughness (deeper etching). The most favorable flat shape of the curves shown in the figure 2 is obtained by using special electrolytes which ensure that the capacitors can be operated at temperatures far below zero. The shape of the curves varies widely, depending on whether the temperature relationship of the AC or of the DC capacitance is determined. Note that DC capacitance has a flatter temperature characteristic.

 

 

Figure 2. Temperature dependence of series
capacitance CS (typical behavior). Reference value:
AC capacitance at 20 °C and 100 Hz

 

 

 

For further information on aluminum electrolytic capacitors please read the following articles:

Aluminum Electrolytic Capacitors - Overview and Key Applications

Design of Aluminum Electrolytic Capacitors and General Features

Equivalent Series Resistance (ESR) for Capacitors

Heat Dissipation and Cooling for Aluminum Capacitors

 

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