Testimonies of DEIS fellowship winners – Ajith John Thomas

This is a brief writeup where I share a glimpse of my professional journey, drawing inspiration from the experiences of researchers and professionals in the field of electrical insulation and dielectrics.

Ajith John
R&D Engineer,
NKT Technology Consulting,
Västerås, Sweden [email protected]

During my Ph.D. at IIT Ropar, India, I delved into the fascinating world of electrical insulation. My research focused on two important research topics in high voltage engineering. The research work in Part A is driven by cable industries in India, wherein a novel measurement technique is introduced for the surface voltage measurement of an overhead covered conductor. Further, this work led to research in coining a generalized measurement method of surface voltages for solid insulators. Part B of the research work focuses on the experimental investigations of breakdown characteristics in needle-plane systems (defects/impurities present in the HV cable insulation) under steady-state DC and polarity reversal voltages. The results and inference from this work would be of relevance and importance to the HVDC cable design as this will further take toward the investigation and prediction of breakdown phenomenon. The journey was both intellectually stimulating and challenging, as I collaborated with brilliant minds in the field.

As luck would have it, I stumbled upon the 2020-21 DEIS Graduate Fellowship Call. This prestigious grant, established by the Dielectrics and Electrical Insulation Society (DEIS), allowed me to explore a specific research topic related to electrical insulation and dielectric phenomena. The fellowship was awarded for a one-year project, closely aligned with my larger Ph.D. research. I submitted a concise research proposal, detailing the context, motivation, project plan, and expected outcomes. The project title was ‘Electric Treeing Breakdown Fields Incorporating Nonlinear Conduction under Steady State DC and Polarity Reversal’. The work proposed was entrenched within a research framework aimed at understanding the breakdown phenomena due to defects in the insulation under steady state DC and polarity reversal fields. The main activities done within the proposal among others is given below.

  1. Electrical treeing experiments under DC and polarity reversal voltages is conducted.
  2. Estimation of steady state (DC) and transient (instant of reversal) breakdown fields using the proposed method which will open the way to further improvement of cable insulation design under steady state DC and polarity reversal fields incorporating the nonlinear conduction of the insulating material.

The potential impact of the research aims at the understanding of the breakdown in HVDC cable insulation and in the presence of a defect, the investigation of insulation breakdown considering nonlinear conduction is a promising route to new design in HVDC cables in both research and industrial environments. Being able to identify when the linearity hypothesis is not valid at the tip during breakdown (electro-thermal), prevents erroneous conclusions and may serve as an improvement in the insulation design. Using the proposed work, the ability to compute accurate field parameters will give an insight to see what is going ‘inside’ the insulation material at a microscopic level and this I believe to open up many interesting possibilities for the rejuvenation of cable dielectric

Furthermore, there was an invited presentation at the prestigious CEIDP conference. (missed the chance to meet face to face with researchers, professionals and presenting virtually due to the pandemic has become the new format at that time).

The fellowship not only provided financial support but also opened doors to networking opportunities. Through DEIS events and conferences, I connected with fellow researchers, industry experts, and potential collaborators. These interactions enriched my understanding of the field and inspired me to pursue a PostDoc.

After my PostDoc at Tu Graz, fast forward to today – I find myself at NKT, a leading company in power cables and accessories. My journey from academia to industry was shaped by among the others, the DEIS fellowship, the connections I forged, and the passion for advancing electrical insulation science. As I reflect on this path, I’m grateful for the opportunities that came my way and the supportive community that propelled me forward.

Remember, every journey is unique, and mine is a blend of curiosity, persistence, and the collective wisdom of my mentors, colleagues, family, friends and DEIS community.

Best Regards and Wishes