Abstract
Liquid Silicone Rubber (LSR) materials have
been applied since more than 20 years as elastomeric
housing materials of composite insulators. Process
technology and material formulations were developed
to meet the high quality requirements that are necessary
for RV outdoor applications. LSR rubbers are typically
applied for housings of large composite hollow and
longrod insulators typically manufactured with the
injection moulding technology. In comparison to typical
High Temperature Vulcanising (HTV) silicone rubbers,
LSR rubbers are not or only slightly filled with
Al(OH)3' The mineral filler Al(OH)3 is used standardly
to set up the required tracking and erosion resistance of
the rubber material. This paper resumes the excellent
long-term outdoor performance of LSR rubber material
grades that are speCially adapted for RV outdoor
applications. The performance evaluation is based on
long-term service experience of insulators in the field in
comparison to the results obtained from material
tracking and erosion laboratory tests. Insulators after 20
years in service in heavily polluted environments were
investigated regarding damages caused by tracking and
erosion. In order to compare the field results to those of
available material tests, the "inclined plane test"
(IEC 60587) and the "low current arc resistance test"
(IEC 61621) on slab shaped test samples were
performed. Insulator designs were evaluated by means
of the wheel test, the 1000 h salt fog test and the 5000 h
test (IEC 62217) that were applied to model insulators.
Erosion resistance of LSR material samples is
quantified by the mass loss, erosion depth and erosion
length. The inclined plane test procedure according to
IEC 60587 with varied conductivity of the electrolytical
test liquid was applied, in order to detect the critical
range of erosion. A comparison to the quantitative
tracking and erosion resistance of HTV (Al(OH)3 filled)
silicone rubbers that are successfully applied for more
than 30 years in RV outdoor applications is given.
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