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  • Arianne Lemo


The high- and medium-voltage electrical and equipment industry is currently facing a major challenge in terms of sustainability and environmental protection, particularly in the management and operation of medium-voltage circuit breakers. CO7 Technologies, based in Lachine, Quebec, is at the forefront of this transformation, initiating the replacement of SF6 gas in its VOX dead tank circuit breakers. SF6 gas, although widely used for its excellent insulating and breaking properties, is also known for its high global warming potential and harmful effects on the environment [1]. With this in mind, CO7 Technologies is moving towards the adoption of "green" solutions, i.e. the use of gases or gas mixtures free of fluorinated compounds. This approach is part of a broader vision of sustainability and environmental responsibility, aimed at minimizing the ecological impact of electrical equipment while maintaining, or even improving, the performance and reliability of circuit-breaker systems. The exploration and implementation of these green gases represents a significant step not only for CO7 Technologies, but also for the electrical industry as a whole, marking a major advance towards more sustainable and environmentally-friendly energy management.

The stages in the search for this green gas solution involve study, design, modeling, simulations, as well as testing and validation of numerical models. Work carried out by organizations such as CIGRE, IEC and IEEE provides guidance and standards for the application of SF6-free gases or gas mixtures in gas-insulated switchgear, covering aspects such as quality and purity, aging aspects, gas handling, and safety and environmental considerations [2], [3]. We also explore publications provided by companies and projects such as National Grid, ABB, General Electric, Hitachi Energy, Eaton, among others, to gain insights into the different solutions they have already implemented.

SF6 free
SF6 CO7's logo


The design of this solution involves :

▪ A study of the general methods used by manufacturers for the design of medium-voltage circuit breakers using available databases.

▪ A study of the standards and techniques used by CO7 Technologies, inc. for the design of medium-voltage circuit breakers using company documentation and archives.

▪ A study of the data and solutions available on platforms such as CIGRE and IEEE Xplore.

▪ The choice of the circuit breaker model at CO7 Technologies on which the final tests will be carried out.

▪ The use of software such as COMSOL Multiphysics in its parallel version in a high-performance computing environment such as the Digital Research Alliance of Canada infrastructure for the circuit breaker's numerical model design and simulation tests.

▪ The realization of a test bench on the company's premises.

▪ The data obtained from the measurements is used to calibrate and validate digital models, while rigorously verifying compliance with current standards.


Quantum programming

This research stands out for its innovative, multidisciplinary approach, its originality lying mainly in the integration of quantum computing and the development of a dedicated Python algorithm. This algorithm is designed to calculate and analyze the properties of various green gas mixtures, thereby identifying the most promising candidate for effectively replacing SF6. This algorithmic approach enables rapid exploration and evaluation of multiple gas combinations, offering unprecedented efficiency in selecting the ideal gas or gas mixture for SF6 replacement.

Photo 1: Quantum computer (source: QUÉBEC SCIENCE accessed January 15, 2024) [4]

The main role of quantum programming is described in [5]:

▪ The calculation of complex properties such as molecular interactions in gas mixtures, which are often difficult to solve using conventional methods,

▪ Performance optimization: the optimal mixture that offers SF6-like properties in terms of insulation and arc-extinguishing capability requires the evaluation of vast combinations and permutations.

▪ Reducing calculation time and improving accuracy levels ▪ Exploring new possibilities too complex to be tackled with conventional calculation methods.

Numerical simulation and High-Performance Computing

In addition, this research exploits advanced numerical simulations, notably through software such as COMSOL Multiphysics, and the use of the infrastructure of the Digital Research Alliance of Canada is envisaged to optimize computing power.

Photo 2: Image of the VOX 38kV circuit breaker taken on the premises of CO7 Technologies

Geometric model of the VOX circuit breaker (Created in COMSOL software with the contribution of Mactar Thiam)

These simulations play a crucial role in validating the performance of the gas selected by the Python algorithm, by simulating its behavior under real-life conditions. This validation stage is essential to ensure the reliability and safety of the gas selected as an alternative to SF6.


Finally, one of the most innovative aspects of this project is the envisaged adoption of digital twin technology. This technology could enable virtual modeling of medium-voltage circuit breakers, providing a platform for testing and optimizing the design and implementation of the SF6 gas replacement solution. The use of the digital twin paves the way for faster design iterations, a better understanding of real-life performance and ongoing product optimization.


By combining these cutting-edge technological approaches, this research is positioned at the frontier of innovation in the field of electrical energy, marking an important step towards more sustainable and environmentally-friendly solutions for the medium-voltage electrical equipment industry.


[1] MINISTÈRE DE L'ENVIRONNEMENT ET DE LA LUTTE CONTRE LES CHANGEMENTS CLIMATIQUES (MELCC). Guide de quantification des émissions de gaz à effet de serre, 2019, 107

[2] Recent development of alternative gases to SF6 for switching applications (accessed January 15, 2024)

[3] L. Bellofatto and P. Sigismondi, "SF6 FREE Alternative - Study of Ternary Mix Natural Gas for Eletrical Insulation Purpose," 2023 PCIC Energy Europe (PCIC Energy), Milan, Italy, 2023, pp. 1-7.

[5] Prieur, B. (2021, September). Quantum programming. In Les webinaires de l'intelligence digitale# 3


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