The equivalent series resistance of polypropylene capacitors has been determined
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 of 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 temperatures, enables to separate the
losses in the conducting material from those in the dielectric and to get their
respective variations as a function of frequency and temperature. These variations
of the equivalent series resistance 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 with in a filtering circuit and is used to evaluate by simulation the losses of
the capacitor.