Outdoor Insulation Technical Committee

Technical Committee Chair

Dr. Refat Ghunem

Aims and Strategic Objectives

The main aim of this technical committee is to develop IEEE guides on evaluation methods of high voltage insulation materials in the outdoors. The following objectives can be highlighted in achieving this aim:

  • Providing a scheduled forum such as workshops, special sessions and meetings, addressing new challenges in the industry.
  • Conducting technical activities such as round robin testing, state-of-the-art literature surveys and workshops on recent advances.
  • Publishing review articles, position papers and special issues in the journals of DEIS.


Outdoor insulators have been widely recognized as backbone components installed in the power system, in order to maintain a reliable power supply. The ability of insulating materials to withstand different weathering conditions in different outdoor environments under high voltages has been an important task defined for both suppliers and users of outdoor insulators in the power industry. The use of standard material screening methods is an essential step conducted in order to qualify outdoor insulating materials for their targeted high voltage applications. Various standard guides have been developed, but the need remains to update or develop new guides addressing new challenges in the power system.

The activities of the outdoor insulation technical committee are mainly focused in two areas, (1) Room-Temperature Vulcanizing (RTV) Silicone Rubber Coatings for Outdoor Ceramic Insulators and (2) Polymeric Insulators for High Voltage Direct Current (HVDC) Systems in the Outdoors. Both of these areas have been gaining interest in the industry in the light of the new paradigms and infrastructure topologies proposed for power system. A call is open for new proposals by new or existing members of the outdoor insulation technical committee in both areas of interests or new areas. New, innovative and promising initiatives within the scope of the outdoor insulation technical committee are also welcome. 

RTV Silicone Rubber Coatings

The use of silicone-based high voltage insulator coatings (HVICs) applied over ceramic insulators has been a popular solution proposed over the past two decades. This solution has been adapted mainly in order to solve the pollution problem of ceramic insulators, offering reliable and maintenance-free outdoor insulation infrastructure in the power system for a descent amount of time. Coated insulators merge the advantages of a thermally stable ceramic insulation bulk made from porcelain or toughened glass and a hydrophobic silicone-based surface.

The main constituent of HVICs is silicone rubber, which possesses a unique self-healing property among other polymers, allowing a low-molecular-weight (LMW) siloxane fluid to diffuse from the bulk of the coating to its surface, thereby washing off contaminants and restoring hydrophobicity. For this reason, many power utilities around the world have been installing pre-coated insulators. To this end, a main task for the outdoor insulation technical committee is to address in-service problems HVICs in the power system and ultimately develop guides or best practices for their life cycle management.

To date, HVICs have been satisfactorily performing for about two decades, but with time they may turn into unknown entities that require attention. An essential focus of this technical committee is to establish state-of-the-art knowledge about advances in the field of HVICs and update the existing experience of their use.

Hand removal: a conventional replacement method of HVICs (from [1] Cherney et al., “End-of-Life and Replacement Strategies for RTV Silicone Rubber Coatings”, IEEE Transactions on Dielectrics and Electrical Insulation, Vol. 21, No. 1, 2014.)

Outdoor Polymer HVDC Insulators

Another focus defined of this technical committee is the application of outdoor polymer insulators in HVDC systems. The new paradigm currently proposed towards achieving a smarter electric grid may require enhanced outdoor insulation systems installed in new power transmission and distribution topologies, such as micro grids, HVDC interconnections, AC/DC micro grids, etc. Therefore, a key objective of this technical committee is to maintain state-of-the-art knowledge about these recent advances and build up on the experience about the behaviour of different outdoor insulating materials in such evolving applications. This ongoing activity facilitates developing new reliable guides for material screening in these new applications.

The ASTM D2303 and IEC 60587 have been widely used standard methods in the industry in order to qualify different polymeric outdoor insulating materials under AC voltages. Both methods specify testing materials with standard voltage levels in a controlled protocol. Therefore, a current focus of the outdoor insulation technical committee has been made to develop an equivalent DC voltage levels. This task is important in the light of the recent concerns raised about the severe erosion reported under DC as compared to AC voltages.

Fig.2. Flow chart of the stepwise voltage method in the inclined plane tracking and erosion test (from R. A. Ghunem, “Using the Inclined-Plane Test to Evaluate the Resistance of Outdoor Polymer Insulating Materials to Electrical Tracking and Erosion”, IEEE Electrical Insulation Magazine, Vol. 31, No. 5, 2015). The equivalent +DC and –DC voltage were approximated in [2] as 70% and 90% of the standard AC, respectively.

Selected Current Activities and Achievements

The following position papers prepared by the outdoor insulation technical committee and published in the IEEE Transactions on Dielectrics and Electrical Insulation can be highlighted. 

  • Cherney et al., “DC Inclined-Plane Tracking and Erosion Test of Insulating Materials”, Vol. 22, No. 1, 2015
  • Cherney et al., “End-of-Life and Replacement Strategies for RTV Silicone Rubber Coatings”, Vol. 21, No. 1, 2014
  • Cherney et al., “RTV Silicone Rubber Pre-coated Ceramic Insulators for Transmission Lines”, Vol. 20, No. 1, 2013

The existing IEEE guide for RTV silicone rubber coatings has been updated as the following.

  • IEEE 1523-2018 – IEEE Guide for the Application, Maintenance, and Evaluation of Room-Temperature Vulcanizing (RTV) Silicone Rubber Coatings for Outdoor Ceramic Insulators 

In addition, a project has been recently initiated (P265) in order to develop a guide for DC inclined plane tracking and erosion test for outdoor insulation applications. Within this activity round robin tests are being conducted in order to verify equivalent DC voltages determined. More details about the the working group on P2652 can be found in the following link: https://standards.ieee.org/project/2652.html (new members are welcome). 

Members of P2652 Working Group

  • Refat Ghunem (Chair), National Research Council Canada
  • Edward Cherney, Consultant
  • Boxue Du, Tianjin University
  • Ayman El-Hag, University of Waterloo
  • Ravi Gorur, The University of Alabama in Huntsville 
  • Suat Ilhan, Istanbul Technical University
  • Shesha Jayaram, University of Waterloo
  • Luiz Meyer, Universidade Regional de Blumenau
  • Massimo Marginotto, TERNA
  • Isaias Ramirez, Instituto de Investigaciones Electricas
  • Simon Rowland, The University of Manchester

Contact details for further technical committee information

Dr. Refat Ghunem: refat.ghunem@nrc-cnrc.gc.ca