Types of Distribution Cells: AIS, GIS and Solid Resin.

Grupo Edmar
Oct 16
4 min read

October 16, 2025 - Distribution Cell Types: AIS, GIS and Solid Resin.

Distribution Cells.

Electrical distribution cells are essential components in medium-voltage systems, as they allow for safe control, protection, and disconnection of electrical circuits. These structures house devices such as switches, disconnectors, current transformers, and busbars, ensuring the continuity of the power supply and protection against faults.

Simply put, a switchgear acts as a "command center" for the flow of power. Its design allows the operator to safely intervene in the system , control maintenance operations, or isolate parts of the circuit when an anomaly is detected.

Today, there are different cell technologies, which vary primarily by the type of insulation they use: air, gas, or solid material . Each has specific applications, particular advantages, and different costs, depending on the needs of the project and the environment where it is installed.

General Classification of Distribution Cells.

Cells can be classified in many ways (by voltage level, design, function, or insulating medium), but the most common is by the type of insulation they use to protect the internal components. This insulation prevents electrical arcs or short circuits between energized parts.

The three most recognized types are:

AIS (Air Insulated Switchgear) : uses air as an insulating medium.
GIS (Gas Insulated Switchgear) : uses SF₆ gas (sulfur hexafluoride).
Solid Resin Cells : use epoxy materials as the main insulator.

In addition to their insulation, they also differ in size, ease of maintenance , cost, and safety level. For example, AIS are larger but more economical; GIS are compact and very secure; while solid resin ones represent a modern, environmentally friendly, and maintenance-free option.

AIS (Air Insulation) cells.

AIS cells are the most common and traditional type of cells used in electrical installations. They operate by using atmospheric air as an insulating medium between energized components. This type of cell is widely used in open substations , industrial plants , or rural installations , where available space is not an issue.

Its main features include:

Simple and accessible design: its construction facilitates inspection and maintenance.
Low acquisition cost: they represent an economical option compared to other technologies.
Compatibility with different configurations: they can be adapted to ring, radial or double-bar schemes.

However, their larger size makes them less suitable for indoor or small-space installations. They can also be more susceptible to environmental factors such as dust or humidity, which requires good ventilation and periodic inspections.

In short, AIS are ideal when looking for ease of operation and maintenance on a budget .

GIS (Insulated Gas) Cells.

GIS cells represent a technological evolution compared to AIS. Their main feature is the use of SF6 (sulfur hexafluoride) gas as an insulating and arc-extinguishing medium. This gas has a high dielectric capacity, allowing the equipment to be drastically reduced in size without compromising its safety or performance.

Among its main benefits are:

Compact design: perfect for small spaces such as buildings or urban substations.
High reliability: Being completely sealed, they are less susceptible to dust or moisture.
Low maintenance: they do not require frequent interventions, since the gas maintains stable insulating properties.
Safe operation: The sealed structure protects personnel from possible electrical contact.

On the downside, GIS systems tend to have a higher initial cost and require responsible environmental management , as SF6 is a greenhouse gas. Therefore, many manufacturers have begun developing SF6-free versions to reduce their environmental impact.

Solid Resin Cells.

Solid resin cells are a modern and environmentally friendly alternative to traditional systems. Instead of air or gas, they use a solid epoxy insulator that encapsulates the conductors and switching devices. This completely eliminates the risk of leaks, internal pressure buildup, or environmental emissions.

Its main advantages are:

Zero preventative maintenance: Solid insulation does not require periodic inspections.
Compact and lightweight design: can be installed in small interior spaces or underground.
Enhanced safety: By not using pressurized gases, operational risk is minimal.
Thermal and mechanical resistance: epoxy materials withstand high temperatures and vibrations.

In addition, solid resin cells are more sustainable , as they eliminate the use of SF6 gas, contributing to compliance with environmental policies and green-certified projects.

This type of technology is frequently used in smart buildings, hospitals, data centers, and modern infrastructure projects , where reliability and sustainability are a priority.

Differences between AIS, GIS and Solid Resin.

The differences between these three types of cells are mainly focused on the insulating medium , the size , the level of maintenance required and the environmental impact .

Feature	AIS	CHALK	Solid Resin
Insulating medium	Air	SF6 Gas	Epoxy resin
Size	Big	Compact	Very compact
Maintenance	High	Low	Minimum
Environmental impact	Low	High (by SF6)	Very low
Cost	Economic	High	Half
Ideal use	Wide spaces	Urban areas	Ecological projects

Each technology responds to different needs. For example, an industrial plant might choose AIS for its ease of maintenance, while a downtown corporate building might prefer GIS for its compact size. A modern technology facility , on the other hand, might choose solid resin to meet sustainability standards.

Advantages and Disadvantages of each Type.

AIS (Insulated Air):

✅ Low acquisition cost.

✅ Easy to install and repair.

❌ More space required.

❌ Sensitive to environmental factors.

GIS (Insulated Gas):

✅ Compact and reliable.

✅ Low maintenance and high durability.

❌ High cost.

❌ Delicate handling of SF6 gas.

Solid Resin:

✅ Ecological, safe and without polluting gases.

✅ Maintenance-free.

❌ Higher starting price.

❌ Technology in the process of global standardization.

The final decision will depend on the balance between budget, available space, required security level and sustainability objectives .

Applications and Recommendations for Use.

The type of cell selected will directly influence the efficiency and safety of the electrical system . Therefore, before making a decision, it is important to evaluate the operating conditions and project objectives:

AIS: recommended for open substations or rural areas with sufficient space.
GIS: ideal for commercial buildings , hospitals , airports or urban centers .
Solid Resin: recommended for sustainable installations or those with strict environmental requirements.

At Grupo Edmar , we understand that every electrical project has unique needs. That's why we support our clients with custom-designed medium-voltage equipment and solutions , ensuring that each electrical system is efficient, reliable, and long-lasting.