Graue Literatur
The mechanical and electrical properties of new transparent silicone materials modified with two fluorescent dyes were investigated by measuring stress-strain behaviour, electrical breakdown strength, capacity and dissipation factor, before and after thermal ageing, as well as electrical and optical partial discharges.
Mechanical properties of the new materials are comparable to the reference and the addition of dyes stabilises them against thermal ageing. All materials are equivalent in terms of breakdown strength and capacity. The added value of transparency and fluorescence make them suitable materials for novel diagnostic applications in HV cable accessories and insulators.
Modern optical partial discharge (PD) detection system based on fiber-optic sensors for PD on-line health monitoring in high-voltage (HV) cable terminations necessarily requires optically transparent or translucent insulation materials. The optically compatible silicone rubbers are the key to facilitate such innovative technology. In this work, AC 50 Hz dielectric strength Eb and mechanical properties of three types of commercially available silicone rubbers have been investigated. The investigations revealed that the translucent silicone rubber has a good mechanical performance but its Eb value is considered too low. However it is sufficiently good for use as base material for rubber stress cones. Unfortunately, its optical transmittance is poor compared to optically clear transparent silicones. On the other hand, the mechanical properties of transparent silicone rubbers do not comply with those demanded from push-on stress cones. In particular, their elongation at break is considered too low for that application. However they provide the Eb values of about 28 kV/mm to 29 kV/mm at 0.5 mm thickness, which are higher than those of the translucent type. Moreover, it was found that the post-curing process does not provide a positive impact on the ultimate elongation of silicone rubbers.