Calorimetric measurement and modelling of the equivalent series of capacitors

The equivalent series resistance of polypropylene capacitors has been deter mined under rated voltage, in the range 1 kHz-1 MHz, between 220 K and 370 K by a calorimetric technique. The original feature of this determination o f capacitor losses lies in the use of the isothermal calorimetry and in the measurement of an electrical power and not of a temperature increase. The frequency dependence of the equivalent series resistance, at various temper atures, enables to separate the losses in the conducting material from thos e in the dielectric and to get their respective variations as a function of frequency and temperature. These variations of the equivalent; series resi stance with frequency at a given temperature have been reproduced by using an equivalent circuit composed of resistors, inductors and capacitors. This model has been verified for non-sinusoidal waveforms such as those met wit h in a filtering circuit and is used to evaluate by simulation the losses o f the capacitor.