As a regular reader of INMR, I pay a lot attention to the various opinions and discussions presented, in particular to the editorial inputs from Ravi Gorur and Claude de Tourreil. In general, I agree with them although occasionally it takes a longer time to ‘digest’ what they write. In any case, a lively discussion on modern outdoor insulation is interesting and certainly beneficial.

However, sometimes I feel a need for continuing beyond where Ravi’s and Claude’s columns often leave off. By this, I mean going a little deeper into problems and especially into a more thorough understanding of phenomena which fall mainly within the domain of research. I took this subject up with the Publisher, Marvin Zimmerman, and here is the result– a column aiming to present my comments upon the latest research being undertaken into insulators, arresters, bushings and cable accessories.

My goal is to report on interesting findings stemming from the efforts undertaken by scientists worldwide and presenting these in a practical and user-friendly way so as to make them most valuable for utility engineers. I know this will be quite a task! At the same time, I would also like to introduce certain people who are still relatively unknown but who nevertheless contribute a great deal to the body of knowledge on modern outdoor insulation.

I sometimes wonder what caused me as a young scientist 25 years ago to become fascinated by the possibility of developing new and more effective types of outdoor insulators. Other choices available to me, such as working in the fields of semiconductors and superconductors, could have proven far more attractive. In spite of this, however, using my background in materials science and HV engineering as well as with my earlier experience in studying ageing of ceramics and polymers in electronic applications, I moved toward the ‘not-so-modern’ discipline of outdoor insulation.

The beginnings were quite simple. I joined a group who, equipped with new ideas as well as sound technical knowledge and employing epoxy resin as the base polymer, started to design and manufacture 110 kV cross-arms for upgrading lines in Poland. Among the problems to be solved were designing the manufacturing tools and developing new test procedures. Similarly, existing tests had to be modified to allow proper material selection and to permit assessing both the insulators and the entire cross-arm construction.

Later, other materials such as silicone and EPDM were introduced and with these came completely new challenges. This, however, must have been the turning point in my professional carrier. I began to realize how complex the phenomena related to the performance of high voltage insulators could be and how much still remained to be learned. At the same time, I began to better appreciate how broad and multi-disciplinary the knowledge in this area had to be, including materials science, physics, chemistry and high voltage engineering among others. All these were needed in order to design a good insulator.

After a rather slow start, composite insulators have now become mature products and the experience gathered has, in general, been overwhelmingly positive. Similarly, polymeric housings have now found applications in cable accessories, arresters and bushings. At the same time, improved ceramic insulators incorporating semi-conducting glazes, have also been successfully introduced. Indeed, today we can talk about several new alternative solutions when it comes to outdoor insulators and utilities are increasingly using these new products.

I am among those who look positively upon all these achievements. Nevertheless, I remain unsatisfied because the benefits of using a polymeric material in place of porcelain or glass are still not being utilized to their full potential. Composite insulators today are often ‘pessimistically-designed’ for a hydrophilic state. I am aware of the fact that some of my colleagues will not agree with me on this point but I strongly believe that this conservatism/pessimism has led to a situation where some of the concepts formulated during introduction of composite insulators have not been fully realized. Shortening of specific leakage distances and better control of stresses as well as potential advantages in compacting and voltage upgrading can be cited as examples in this regard.

Insufficient knowledge of the basic phenomena behind the long-term performance of materials used together with lack of reliable testing methods and means for product assessment are responsible for this situation.

Many questions remain unanswered. As a result, there is a great need for additional research to cover such pertinent aspects of outdoor insulation as: (1) production and performance of high-performance materials; (2) understanding electrical, chemical and mechanical deterioration mechanisms; (3) proper dimensioning, design and manufacturing of insulator materials; and (4) development of methods for monitoring performance as well as deterioration of insulators in service. Universities, research institutions and the industry (including both manufacturers and users of insulators) are typically behind such investigations and, where the results obtained are made public, this column will report and provide commentary on these findings.