Losses

The technical capacitor model presented in the introduction page on the capacitor models shows that the impedance real part of a technical capacitor is due to the capacitor series resistance r_s and to the capacitor parallel resistance r_p.

The contribution due to r_s is important at high frequency while the contribution due to r_p has a dominating effect essentially at low frequency, in particular at the industrial frequency.

In r_s are collected the resistances of the conductors, connections, electrodes and electrolyte if necessary.
In r_p are collected the losses due to the dielectric polarisation, the dielectric resistance, the losses due to the leakage current and the charges redistribution phenomena if necessary.
In a theoretical or mathematical capacitor, the power is purely reactive. There are no losses.

Equivalent Series Resistance

Tangente delta

Source: Garmanage: Roland Gallay