Capacitors voltage variation

Systems prone to frequent voltage variations Capacitor elements are non-self-healing and are generally provided with internal fuses An inductor coil may not be necessary with such capacitors... 

When selecting the voltage of the capacitor units care must be taken that during operation the voltage across the capacitor units does not fluctuate beyond 10%. If this happens the voltage rating of the capacitor units must be chosen so that the variation across the units under unfavourable operating conditions does not exceed 10%. 

We have considered ihe niaxinuini overcunenl facior I or illustration. It corresponds to the nia.ximuni permissible upper variation in the capacitance value of a capacitor or a bank. One can. however, consider a lower factor depending upon the maximum permissible upper variation for a particular type (voltage and VAr rating) of capacitor unit or hank. A factor of. ]f> is, however, recommended lor capacitor duties. See also Section 2.5.6. 

Equation (1) is the basis for using EIS capacitors or ISFETs to measure changes in Vo- If an ISFET is used, the measured quantity is the threshold voltage, which is equal to the flat-band voltage plus a constant. In both cases only variations of Vo can be measured, because the other terms in (1) are not independently known with sufficient accuracy. 

The remarkable stability of the capacitance of the SIKO against variations in bias, temperature, frequency and time of operation is a consequence of the superior properties of its ONO dielectric. In contrast to aluminum and tantalum capacitors, the SIKO is a symmetrical device. It shows no significant voltage dependence of the capacitance, as the high s ceramic capacitors do. Only polymeric capacitors show a lower dependence of capacitance on bias than a SIKO. 

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