Electrical distribution switchgear based on fully gas-insulated technology (GIS), now available without fluorinated gases, has established itself as the most reliable technological solution

Behind something as commonplace as switching on a light or using our household appliances lies a complex electrical infrastructure built around an interconnected grid that relies on technology to operate correctly. Today, we take a closer look at one of the key elements of the grid, distribution switchgear, and at the differences between the two predominant insulation technologies: GIS (Gas-Insulated Switchgear) and AIS (Air-Insulated Switchgear).

The enormous expansion of the power grid during the 20th century drove unprecedented progress in electrical engineering. Step by step, this development created a power grid capable of supplying a population whose day-to-day demand for electricity continued to grow.

This technological journey encompasses countless advances and engineering decisions that have brought us to where we are today, at a time when the electrification of society is undergoing a major transformation aimed at decarbonising economic activity and reducing society’s environmental impact.

Among these innovations is the technological development of medium-voltage distribution switchgear, equipment designed to receive and distribute electrical power to transformers, where voltage levels are transformed, while providing the necessary switching, isolation and protection functions. Two main insulation technologies have traditionally been used: GIS (Gas-Insulated Switchgear) and AIS (Air-Insulated Switchgear).

Although both technologies provide insulation and enable electrical current to be switched and isolated safely, the development of urban infrastructure, together with the resulting need to optimise the space occupied by electrical switchgear and minimise its footprint, as well as the critical requirement for reliability, has made GIS the predominant technology.

Let us see why.

Gas-insulated switchgear: the predominant technology

Picture a city centre. Space is shared by residential buildings, roads, shops, leisure and cultural facilities, hospitals, railway infrastructure and numerous other public services. Land availability is limited, while demand for electricity is both intensive and continuous. At the same time, people are constantly moving through streets and public areas.

In this environment, where safety and security of supply are essential and the space available for electrical equipment is limited, gas-insulated technology has become an ideal solution.

GIS technology stands out in terms of reliability, safety, sustainability and space optimisation.

What began as an ingenious insulation solution for installations with space constraints has evolved into one of the technological pillars of the world’s most advanced power grids.

But let us take a closer look at this technology and its main alternative.

What is GIS, or Gas-Insulated Switchgear?

GIS is a technology in which busbars, the main circuit, and switching and connection devices are insulated and enclosed within gas-tight, sealed-for-life stainless-steel compartments containing a dielectric gas as the insulating medium.

Thanks to this configuration, GIS distribution switchgear provides:

• An extremely compact design and configuration.
• Greater protection against external environmental conditions.
• High operational reliability.
• Greater safety for operators and users.
• Reduced maintenance requirements throughout its service life.

For these reasons, GIS technology has become predominant in electrical distribution equipment used in transformer substations, urban infrastructure, industrial installations, renewable-energy facilities, ports, airports, hospitals and data centres, among many other applications.

What about AIS, or Air-Insulated Switchgear?

While GIS uses gas to insulate its internal components, AIS (Air-Insulated Switchgear) uses ambient air as its insulating medium.

As a result, live components must be separated by greater physical clearances, and insulation performance is more dependent on the environmental conditions surrounding the equipment.

AIS solutions have been widely used. However, their greater space requirements and their increased exposure to environmental conditions can result in additional costs, particularly due to more frequent periodic maintenance. Consequently, in many applications these solutions have increasingly been replaced by more compact and robust GIS solutions.

What are the main differences and advantages of GIS over AIS?

1. Smaller footprint

The most immediately apparent advantage of Gas-Insulated Switchgear (GIS) is its compactness.

Because it uses an insulating medium with a higher dielectric strength than air, components can be installed much closer together. This can reduce the space required for an installation by 80% to 90% compared with an equivalent AIS solution.

2. Higher reliability

Active components are protected inside sealed enclosures, minimising the impact of environmental conditions.

This significantly reduces the risk of incidents caused by:

• Humidity.
• Dust.
• Industrial pollution.
• Saline environments.
• Wildlife or vegetation.

3. Reduced maintenance

Because GIS equipment is protected against weather conditions and contaminants, fewer maintenance interventions are required throughout its life cycle, contributing to higher grid availability.

4. Increased safety

Enclosing live parts reduces exposure to accidental contact and improves performance in events such as an internal arc.

5. Ready for critical infrastructure

Data centres, hospitals, transport systems, industrial facilities and renewable power generation plants demand solutions offering high levels of reliability and continuity of service.

These are precisely the environments in which GIS technology demonstrates its full potential.

The evolution of GIS technology: towards fluorinated-gas-free solutions

For decades, a large proportion of GIS technologies have used SF₆ (sulphur hexafluoride) as a dielectric gas due to its excellent insulating properties.

However, regulatory developments, particularly within the European Union, together with global sustainability targets, have driven the electrical equipment industry to develop new insulation solutions that retain the main advantages of GIS technology while eliminating the use of SF₆.

The need to accelerate the electrification of our economy through a sustainable approach has further reinforced the already strategic role played by the electrical equipment industry. The sector is currently making a major contribution towards achieving society’s decarbonisation targets.

In this context, the various initiatives promoted by the European Union to reduce the environmental impact of human activity, including new regulations governing fluorinated gases such as SF₆, are driving industry towards a future without these gases.

The electrical industry uses such gases as part of the dielectric solution required to ensure the safe operation and handling of electrical equipment such as distribution switchgear. GIS technology has played a fundamental role in the industry for decades, helping ensure both security of electricity supply and operator safety, while providing gas tightness and enabling gas recovery at the end of the equipment’s service life.

Today, this technology is evolving towards a scenario in which alternatives to SF₆ are taking over.

Among the main insulating media introduced by leading manufacturers, the most competitive solutions are those capable of maintaining comparable technical and operational characteristics while requiring the fewest possible changes for distribution system operators.

This is particularly important when adapting the power grid for the future without introducing significant changes to established equipment and operating practices.

This is where industrial natural air insulation comes into play. Used in the technology developed by Ormazabal, among other manufacturers, this solution uses gases naturally present in the atmosphere which, after a controlled industrial process, provide the insulating medium for distribution switchgear. This eliminates environmental moisture from the insulating medium while providing the appropriate dielectric insulation required by the equipment.

One of the main industrial advantages of this technological alternative is that it is patent-free, facilitating scalability and accessibility across the electrical industry.

Furthermore, a key factor that makes Ormazabal’s proposal particularly suitable for the grid is its ability to implement this technology while maintaining the same design, operation and usage parameters as SF₆-insulated equipment.

As a result, Ormazabal’s range of fluorinated-gas-free solutions for primary and secondary distribution networks up to 24 kV has attracted significant interest since the first alternatives entered the market.

Ormazabal’s fluorinated-gas-free solution

As part of its commitment to leading the sustainable transformation of power grids, Ormazabal has invested a decade in technological research to develop an innovative fully insulated alternative that does not use SF₆ as a dielectric gas.

The solution uses industrial natural air, manufactured under controlled and tested conditions using only components naturally present in air. It is commercially accessible and patent-free.

The technology reduces environmental impact while addressing the new European regulatory framework for fluorinated gases and supporting climate-neutrality objectives.

Ormazabal’s technological alternative has been very well received by the market. Following more than 10 years of continuous research, it retains the design, operation and maintenance parameters of existing equipment backed by more than 30 years of proven experience, making it one of the market’s most comprehensive solutions.

The Ormazabal technology proposition ensures ZERO changes to design, operation and maintenance parameters, together with ZERO uncertainties regarding health, safety, reliability and performance.

Ormazabal’s fluorinated-gas-free solutions for secondary and primary distribution offer the following key features:

• Naturally sourced gas.
• Natural air components.
• Industrially manufactured.
• Fully accessible.
• Minimum filling pressure.
• Known behaviour.
• Proven gas tightness.
• Easy operation and use.
• Innovative switch-disconnector.
• Circuit breaker based on proven technology.
• Optimised dimensions.
• Similar footprint.
• Digital native.
• Sensors.
• Automation.

This launch is aligned with Ormazabal’s strong commitment to European climate-neutrality targets and people’s well-being, while promoting the electrification of society.

These challenges are part of Ormazabal’s DNA and are being actively addressed through the digitalisation of the power grid, facilitating the connection of electric mobility infrastructure, energy storage and renewable energy sources.

Would you like to learn more about Ormazabal’s ZERO solutions for the power grid?