Design
The 3FL insulator housing is a one-piece HTV1 silicone
rubber housing made by the one-shot injection molding process. The HTV silicone
is directly molded onto the core rod by overlapping the triple junction point
and part of the metal end fittings. The design ensures a total enclosure of the
most sensitive part of a silicone insulator - the junction zone (metal end
fitting/FRP rod/silicone housing), where usually the highest electrical field
strength is concentrated. This overlapping system eleiminates any need of
traditional sealing systems while preventing any moisture ingress attacks.
Core
The core rod is boron-free, corrosion-resistant ECR2
glass-fiber-reinforced plastic rod (FRP rod). Due to the extremely high
hydrolysis and acid resistance of the FRP rod the risk of so-called brittle
fracture is completely eliminated on 3FL insulators.
End fittings
The end fittings, made of hot-dip galvanized forged
steel or ductile cast iron, are directly attached to the FRP core rod by
circumferential crimping process. Each crimping process is strongly monitored
with a special control system. A complete range of end fittings according to
the latest IEC and ANSI standards is available up to 210 kN of SML. The 3FL is
100% exchangeable and compatible with existing insulators and line hardware of
all types.
The special design of the end fitting in the junction
zone reduces the electrical field strength and partial discharge to a minimum,
accordingly inside the junction zone as well as on the silicone housing surface
by modeling an integrated grading ring. This relaibly prevents corrosion of the
insulating material and eliminates the risk of subsequent failure of the
insulator.
HTV silicone rubber housing for best pollution
performances
The excellent pollution layer characteristics of the
HTV silicone rubber ensure maximum reliability of the 3FL insulator, even under
extreme service conditions. The extremely hyrophobic housing prevents the
formation of conductive film on its surface. Even the most severe ambient
conditions, such as salt fog in coastal regions or dust-laden air in industrial
areas, cannot impair the intrinsic hydrophobicity of the HTV silicone rubber.
Surface currents and discharges are ruled out. Neither water nor dirt on the
housing surface can cause insulator flashovers - a significant factor in
insulator performance.
1HTV: High-temperature vulcanizing
2ECR glass: Electrical- and corrosion-resistant glass