Comparison of Laboratory Test, Field Station and Service Performance of HTV and LSR Hollow Core Housings

Abstract

Liquid Silicone Rubber (LSR) and High Consistency Silicone Rubber (HCR/HTV) materials were both applied successfully for more than 30 years as elastomeric housing materials of Hollow Core Composite Insulators. Process technology and material formulations were developed to meet the high quality requirements that are necessary for HV outdoor applications under severe service conditions. LSR and HTV rubbers are typically applied for housings of large composite hollow insulators and HCR/HTV mainly for transmission line insulators. Typical manufacturing methods are the extrusion and injection moulding technology. In comparison to HCR also known as HTV silicone rubbers, LSR rubbers are not filled with Al(OH)3. This mineral filler is mainly applied to set up the required tracking and erosion resistance of the housing material which is an important property regarding long-term electrical performance, but not the only one of importance. Beside tracking and erosion, the hydrophobicity properties, the arc resistance and the mechanical properties have to be considered. This is necessary in order to understand and to evaluate the entire ageing process of materials in general. Thus, a more complex setup of test/stress conditions is necessary. The lack of representative and relevant standard ageing tests makes this entire performance evaluation more challenging and the assessment of test station and field data mandatory.