Series Capacitance

Formula

Description

Capacitors in series combine using the reciprocal formula, which is the opposite of how resistors combine. The total capacitance is always less than the smallest individual capacitor. This happens because series connection effectively increases the distance between the outer plates while keeping the same charge on each capacitor. Series capacitors are used to increase the overall voltage rating of a capacitor bank, since each capacitor shares a portion of the total voltage. They are also used in impedance matching networks and RF tuning circuits.

Variables

• Ctotal — Total equivalent capacitance (F)
• C1, C2, ... Cn — Individual capacitor values (F)

Practical Notes

When capacitors are placed in series for higher voltage ratings, add balancing resistors in parallel with each capacitor to ensure equal voltage distribution. Without balancing, leakage current differences cause unequal voltage sharing that can exceed individual ratings.