On the photo: Franck Thomas, EDF

Interview with Franck Thomas from EDF – CIGRE Paris 2022

Transformers Magazine’s editor-in-chief Mladen Banovic talks with Franck Thomas, expert in transformer diagnostics at EDF–DTG, at CIGRE Paris 2022.

Franck, thank you for joining us for the interview, please tell us a bit about yourself, your background education, and your job in the company.

So, at the very beginning of my career, I started working in EDF as a grid technician. After five years on that job, I resumed my studies with EDF’s help. I studied engineering for five years, and after my graduation, I went to work in research and development, on the planification of medium voltage networks. After that, I transferred to the department where I currently work, in 2007. My work involves exclusively transformers, particularly transformer diagnostics. I have been here for about 15 years, in a team of colleagues who are a mix of engineers and technicians, and we mostly work on the production parts. This includes step-up transformers for hydraulic, nuclear, fossil-fuel, and thermal power parts. We perform some electric tests on-site, sample analyses, as well as some electrical tests. These include some basic tests like ratio, winding resistance, insulation resistance, and then partial discharge on site – we have an inducer test module, and we also do acoustic tests. We have a very wide range of diagnostic methods.

So, the main customer of your company EDF–DTG is EDF, more precisely, your company is an EDF company providing services to EDF?

Yes, about 95 % of our activities are for EDF and sometimes we assist some large customers of EDF, as well. However, we do not work a lot for external companies.

What are the most important projects you are working on this year, such as the development of new methods? Perhaps there are even some interesting new trends in diagnostics?

Yes, there are a few. For instance, we provide online measurements for a lot of customers. We have around ten years of experience in DGA monitoring on hydraulic pumps. Also, on the EDF’s part, we are expanding our monitoring activities to bushings, thermal monitoring, etc., so that we will have a complete overview of our fleet. That will cover hydraulic, nuclear, and thermal parts. It is going to be a huge, long-term project, involving not only EDF–DTG but also research and development of other engineering departments in EDF, as well as communication.

In the development, we are focused on research and development of acoustic localization within the transformer. In terms of diagnostics, using an acoustic sensor on the tank could be quite interesting, for example. It is easy to install, and with triangulation, we could find out if there is perhaps some fault or a problem inside, and locate it. It is an advantage to know where to perform reparation.

Another important project for my department is to improve the mobile units we have and upgrade them for partial discharge with an induce test on the field, for easier and more efficient testing.

These are the three most important projects, in brief.

Here at CIGRE, you are participating in some CIGRE working groups as an expert. Please, tell us in which groups you are active and how you are contributing.

Well, I try to be as active as possible, and that depends on the available time. In the joint group of A2 and D1, group JWG 77, I participate in the interpretation of dissolved gas analysis monitoring. It is a remarkably interesting and large group. We are exchanging information in the attempt to create a large database and make some statistics, clusters, etc. This is actually the only working group in CIGRE in which I am active. Hopefully, I will be able to work in a new group that will be created around the DGA monitoring analysis. In IEC, I will work in an advisory group. I am the convener, but I had to skip one year because I did not have time due to COVID-19 and some problems relating to an interface between a transformer and the device monitoring bushing tap adapter, quite mechanical, but there were some problems when we started.

You have told us that you are a loyal reader of Transformers Magazine. What has been your experience as our reader so far? What content do you like and is there anything missing, or something we can improve?

Well, Transformers Magazine’s editions are very substantial and abundant in information. What is important for me is perhaps the news, especially relating to the manufacturers. I also like to read about new metering equipment, especially diagnostic ones. There are some important topics relating to manufacturing. It is a very specialised magazine and you cover plenty of relevant topics. I mostly read the parts that are relevant to me. The topics I am most interested in are diagnostic monitoring, new sensors, new devices, as well as interpretation methods. I mainly focus on topics related to my activities.

Thank you very much, it was a pleasure talking to you!

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