Impedance analysis of long term aged thermoplastic elastomeric insulators

The universal phenomena of aging were investigated for a third generation, environmentally-friendly, thermoplastic elastomeric (TPE), 28 kV polymeric insulators using impedance analyzer, Autolab/PGSTAT30. Impedance analyzer is a versatile, non-invasive tool that aids in exploring the characteristics of a variety of materials including biological tissues, kiwifruit, semiconductor materials and high voltage, outdoor polymeric insulating materials. The insulators were aged for 6000+ hours under slightly modified IEC 61109 multistress conditions. Both vertical and horizontal insulators as required by IEC 61109 were analyzed from 50 Hz to 5000 Hz. Only low frequency range was used since the samples in real world are used at either 50 or 60 Hz. The aged samples showed relatively lower values for both Z\´ and Z" parameters (real Z and img Z respectively, where Z is the total impedance). This variation is different for various frequency ranges indicating the effect of frequency on the molecular structure of the aged samples. Knowing these changes enables to suitably modify the processing variables and chemical composition of the polymers for future manufacturing.