Study of degradation processes of two- and three-component insulating composites

Electrical technology diagnostics is a branch of science examining the actual state of electrical machinery under the operation when using two basic accesses. The first and older one is an “off-line diagnostics”. It means a device or an appliance subjected to diagnostic process need to be for example disconnected from circuit, turned off or stopped. An on-line diagnostics - diagnosing a device during its operation is the second access, nowadays more and more developed. Both diagnostics require detailed knowledge of physical processes taking place in diagnosed materials, devices etc., hence it is necessary to monitor the trends of specific parameters in time. This knowledge is mainly needed in the case of newly developed material application. A mathematical model is designed to describe observed physical processes according to the measured parameters in the diagnostic system. The paper presents results of long-term experiment dealing mainly with thermal and voltage ageing of electrical insulating materials. Both two and three component dielectrics are considered. Study is searching the correlation between ageing of the materials samples and ageing of the whole electrical devices. Tested samples of two and three component dielectric materials were subjected to the long-term laboratory ageing. The test samples were treated by high temperature, by increased voltage and cycled humidity. Different sets of samples were subjected to each of mentioned ageing factors. Ageing characteristics were calculated from different monitored parameters for each ageing factor. Important electrical parameters such as dissipation factor and resistivity vs. ageing time of aged materials are presented. Correlation between ageing characteristics of the same material and different ageing factors has been searched.