Pressurized air cables vs. XLPE cables

Less reactive power, more usable transmission capacity

Due to their insulation geometry, XLPE cables have relatively high capacitance. As a result, reactive power currents are generated, which can require additional compensation measures, particularly on long transmission routes.

Pressurized air cables have approximately five times lower capacitance. This significantly reduces both reactive power demand and charging currents.

The main reasons are the larger insulation gap provided by the pressurized air insulation and the lower dielectric constant of air (approximately 1) compared with XLPE (approximately 2.5).

Benefits for power system operation

Lower reactive power currents provide several advantages:

• Higher usable active power transmission
• Reduced charging currents
• Lower need for reactive power compensation
• Improved efficiency on long transmission routes
• Greater flexibility in network planning

As a result, pressurized air cables combine the advantages of underground transmission with electrical characteristics that are particularly beneficial for high-capacity and long-distance applications.

Integrated condition monitoring

XLPE cable systems often rely on additional monitoring solutions such as partial discharge monitoring, temperature measurement, or sheath current analysis.

Pressurized air cables feature integrated pressure monitoring that continuously supervises key operating parameters and enables the identification of affected sections within the system.

Continuous system transparency

Because the insulating medium is continuously monitored, the operating condition of the system can be assessed throughout its service life.

This provides several advantages:

• Continuous condition monitoring
• Integrated pressure monitoring
• Early detection of anomalies
• Identification of affected sections
• Support for condition-based maintenance
• Increased operational reliability

The integrated monitoring concept makes condition assessment an inherent part of the transmission system rather than an additional external function.

Non-combustible enclosure

XLPE cables use polymer-based insulation materials.

Pressurized air cables use dry pressurized air within a fully metallic aluminium enclosure.

The design is non-combustible and is particularly suitable for applications with enhanced requirements for fire safety and operational reliability, such as tunnels, industrial facilities, and critical infrastructure.

Advantages of the enclosed metallic design

The aluminium enclosure provides multiple functions in a single system component:

• Mechanical protection
• Grounding
• Pressure containment
• Electromagnetic shielding
• Non-combustible construction

This combination supports a robust transmission system with high levels of safety and reliability, even in demanding installation environments.

Designed for Sustainable Energy Infrastructure

Pressurized air cables use air as the insulating medium and require neither SF₆ nor PFAS-based insulation systems.

By using air as the insulating medium, incorporating a high proportion of aluminium, and eliminating the need for SF₆ and PFAS-based insulation systems, pressurized air cables provide favourable conditions for recycling, circular economy principles, and long-term sustainable energy infrastructure. They support the requirements of modern power grids for environmental compatibility, resource efficiency, and future readiness.

Additional Benefits

• Air as a natural insulating medium
• No use of SF₆ or PFAS-based insulation systems
• Elimination of persistent fluorinated substances
• High aluminium content
• Excellent recyclability
• Low environmental impact throughout the lifecycle
• Reduced magnetic field emissions

Cost Efficiency Over Decades

The evaluation of transmission systems is not based solely on initial investment costs.

Energy losses, reactive power demand, maintenance requirements, repair times, and service life all influence total costs throughout the lifecycle of the asset.

Pressurized air cables particularly reduce energy losses and reactive power demand, which can contribute to lower operating costs over the long term.

Additional Benefits

• Reduced energy losses
• Lower reactive power compensation requirements
• Lower operating costs over the system lifetime
• Support for lifecycle-oriented asset management
• Long-term economic efficiency for high-capacity transmission systems

Rapid Restoration in the Event of a Fault

In the event of a fault, repairs to XLPE cable systems can take several weeks or even months due to jointing work and the procurement of replacement components.

Pressurized air cables are based on standardized pipe sections and bolted-free flange connections. Repairs can typically be completed within a few days.

Additional Benefits

• Short repair times
• Rapid restoration of transmission capacity
• Standardized system components
• Reduced outage durations
• Improved system availability
• Support for resilient grid operation

Every Technology Has Its Area of Application

XLPE cable systems benefit from extensive operational experience and are widely established around the world.

Pressurized air cables are a newer technology. While the number of reference projects is still smaller, type testing has already been successfully completed and initial customer projects have been implemented.

The selection of the optimal technology therefore always depends on the specific requirements of each project.

When Are Pressurized Air Cables an Attractive Alternative?

Pressurized air cables offer particular advantages for:

• High power transmission capacities
• High current ratings
• Long transmission distances
• Tunnel and duct installations
• Sustainable infrastructure projects
• Grid expansion in areas with limited available space
  
  

While XLPE cable systems remain a proven and widely adopted standard solution, pressurized air cables expand the range of modern transmission technologies and create new opportunities for high-capacity, sustainable, and future-ready power networks.