Influence of Harmonic Distorted Voltages on the Power Loss of Func-tionally Filled Silicone Elastomers

Abstract:
The increasing use of power electronics in the electrical grids causes an increase influence of harmonics, which leads to a distortion of the grid voltage waveform with voltages of higher frequencies. These superimposed voltages can be a challenge for the insulation of electrical equipment, since the additional frequencies can cause a higher thermal loss in the insulating materials, resulting in an acceleration of their aging. Thus, to ensure a safe use and a long durability of electrical equipment, the design of their insulation systems should take both the behaviour of the base materials and that of their interfaces under harmonic distorted voltages into consideration. This contribution presents two methods to determine the dielectric power losses, in relation to the dielectric properties, of the insulation material under influence of harmonics. Firstly, the dielectric properties of the silicone samples are determined at single frequencies. To gain insight of harmonics induced loss, experiments are carried out next with harmonic distorted voltages. The power loss of the material is obtained by a calculation method proposed and then compared with a direct power measurement. Based on the results, both methods show comparable behaviour with sufficient accuracy. The power loss increases when harmonics are present in the voltage waveform. This suggests the possibility of dielectric heating and can shorten the durability of an insulation system.