Polymeric Insulators - an Overview

Since the 1960s, polymeric insulators have been used in transmission equipment in addition to conventional ceramic or glass insulators.  Polymeric insulators were originally used in areas with high pollution, high risk of vandalism and in urban areas.  Today though, their use has greatly expanded and they are used at almost all voltage levels. They are also known as composite insulators. 

Some of the advantages of polymeric insulators are
  • They are hydrophobic and do not allow the accumulation of water on their surface, thus preventing surface currents and flashovers. 
  • Their light weight enables easy fitment with smaller cranes and increased clearance distance between conductor and the ground.
  • Their higher mechanical strength enables transmission towers to be placed at longer spans. 
  • They are resistant to pollution. 
  • Composite insulators do not allow the accumulation of dirt.  Hence, the cleaning and maintenance costs of the insulators are reduced. 
The disadvantages of polymeric insulators are that damages in these insulators are difficult to detect. These insulators are also vulnerable to erosion and tracking on the surface.Their life expectancy is not predictable