High-voltage substations

Infrastructure facilities, industry, and private households around the world require more and more electrical energy

High-voltage substations, the node points of today’s complex power transmission infrastructure, play a key role in meeting this demand safely and reliably. Siemens supplies them on a turnkey basis.     Wherever you are, Siemens is your reliable partner for the one-stop planning and construction of customized, state-of-the-art high-voltage substations.

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Meeting your demands

Solutions and services for the entire life cycle

You expect comprehensive expertise in power transmission, technology leadership, long-standing experience from utility and industry projects around the world, and reliable financial strength? Then Siemens is your partner of choice for one-stop high-voltage substation solutions, on budget and on time. 

Much more than you would expect

Siemens’ scope of supply comprises much more than the high-voltage equipment that is required for the operation of a substation. It includes high- and medium-voltage switchgear, transformers, and equipment as well as all ancillary systems for control, protection, communication, and condition monitoring. Moreover, Siemens is in a position to supply the entire high-voltage substation as an individual turnkey solution or even act as your general contractor for engineering, procurement, and construction (EPC) / engineering, procurement, and construction management (EPCM) projects.  

Siemens provides the entire range of services, technologies, and components that are required for the successful construction and operation of a high-voltage substation of any type. It is up to you to select from a comprehensive range of available services:   

  • Concept, planning, engineering
  • Project execution including project management and manufacturing of all key components
  • Commissioning
  • Operation 
  • Maintenance, refurbishments, upgrades, dismantling of old equipment
  • Financing

Siemens helps industry customers focus on their core business by supplying fast, reliable, complete solutions that are based on a high degree of flexibility, continuous development, and outstanding consulting expertise for all steps of a high-voltage substation project: 

  • Concept, planning, engineering
  • Support in grid code compliance as well as in 
  • handling and processing official planning documents and approval procedures
  • Project execution including project management and manufacturing of all key components
  • Commissioning
  • Operation
  • Maintenance refurbishments, upgrades, and dismantling of old equipment 
  • Financing
Reliable partner

A convincing success story

Siemens has proven to be a reliable, trustworthy supplier of high-voltage substations for all voltage levels and for all applications – from basic substations with a single busbar to interconnection substations with multiple busbars or a breaker-and-a-half arrangement for up to 800 kV, 8,000 A, and short-circuit currents of up to 100 kA.

The numerous Siemens high-voltage substations that are in operation worldwide comprise grid access solutions for wind farms as well as exceptionally compact solutions that bring high voltage right into the centers of consumption and ultra-high voltage substations for the backbones of transmission grids.


Siemens serves customers from all across the globe, and no wonder the number of successfully completed projects keeps growing steadily.

Systems overview

Types of high-voltage substations

The various types of switchgear that are available for high-voltage substations make it possible to provide flexible, individual solutions. Here’s an overview of the different kinds of high-voltage substations and their main advantages. 

Reliable, proven, cost-efficient

Substations with air-insulated switchgear

Siemens high-voltage substations with air-insulated switchgear (AIS) are the cost-efficient choice for rated voltages of up to 800 kV. They are renowned for highest reliability, economical operation, and low maintenance requirements. 


The Siemens experts always consider the electrical parameters as well as the environmental conditions to which a substation is exposed. That’s why Siemens AIS substations meet even the most demanding challenges and provide:

  • an optimum solution when space restrictions and environmental circumstances are not an issue
  • easy implementation of a wide range of standard applications
  • reliable switching for up to 800 kV, rated currents of up to 8,000 A, and short-circuit currents of up to 80 kA

Compact, powerful, adaptable

Substations with gas-insulated switchgear

Siemens high-voltage substations with gas-insulated switchgear (GIS) are ideally suited to meet some of today’s most important requirements: bringing power on high-voltage levels right into the centers of urban areas. With almost 50 years of GIS manufacturing experience, the largest installed base of GIS, and a long track record of superior turnkey supply, Siemens is able to provide true one-stop GIS solutions that even comprise operational training. 


More than 34,500  Siemens GIS bays are currently in operation in GIS substations all over the world – even in most challenging environments. The comprehensive range of GIS for rated voltages from 72.5 kV to 550 kV provides ideal solutions for indoor and outdoor switching applications up to the highest performance rates that require:

  • a small footprint
  • outstanding reliability
  • very low noise and electromagnetic emissions

Modular, versatile, clever

Mixed technologies substations

Mixed technologies substations – or hybrid substations – are mainly used for the refurbishment and expansion of substations with air-insulated outdoor and indoor switchgear, particularly in cases when such modifications need to be accomplished with the substation in service. As space and time are main cost factors in the expansion of substations, solutions with Siemens highly integrated switchgear (HIS) provide the possibility to quickly adapt a substation to today’s demands. The space-saving HIS circuit breakers, disconnectors, grounding switches, and instrument transformers are housed in pressure-resistant, gastight enclosures and require no additional space. Busbars and bushings originate in conventional AIS technology.


Mixed technologies substations are:

  • ideally suited for new substations when space is limited
  • outstandingly compact thanks to the hybridization of GIS and AIS technology
  • clearly structured, with good access to all equipment
  • modular to suit virtually any network concept

Flexible, robust, plug and play

Portable power solutions increase grid development agility and resilience

Siemens’ portable power solutions are an ideal plug and play solution when it comes to achieving urgent grid connection, renovation, or expansion in challenging environments. Their mobile and modular design allows to take up the challenge of tight construction timeframes, natural disasters, and operational restrictions. They ensure maximum flexibility of design and utilization, excellent reliability, and a high return on investment thanks to:

  • fast installation, small footprint, and easy relocation
  • minimum interface management, full pre-commissioning prior to dispatch, and little on-site work
  • robustness to transportation and handling constraints, as well as harsh environments


Customized, convenient, complete

Turnkey solutions

Siemens turnkey solutions for high-voltage substations incorporate the strong performance of one of the world’s leading engineering companies and one-stop supplier of power transmission products, solutions, and services. The scope of services comprises consulting, project management, system planning, engineering, commissioning, comprehensive after-sales support, and customized financing solutions. Centers of competence and branches all over the world create local value and ensure that Siemens experts are within close reach of every project.


With decades of practical experience as a general contractor and equipment manufacturer plus a vast number of successfully completed projects all over the world, Siemens has all it takes to design, construct, and operate turnkey electrical substation solutions that provide:

  • a one-stop approach comprising all technical, financial, and ecological aspects of the station’s entire life cycle
  • customized solutions based on proven Siemens technologies, even for the most challenging demands
  • freedom from coordination efforts and minimized financial and technical risk


Learn more about our turnkey solutions for high-voltage substations

Further information

Topical subjects

Project references

High-voltage substations in practice

Reliable nodes in power systems around the world


Approx. years of experience

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Countries worldwide

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Projects in total

  Comprehensive expertise and many decades of practical experience are at the heart of all Siemens AIS and GIS high-voltage substations. They serve even the highest voltage levels and are used in the most demanding environments.              

The largest GIS in North America increases electric system reliability and reinforces New Jersey’s transmission backbone

Public Service Electric and Gas Company SE&G | Bergen substation, USA   This project broke records in terms of scale and performance. Gas-insulated single-pole bus ducts with a total length of 2,700 meters connect the GIS accommodated in the 85-meter-long switchgear building with the air-insulated part of the substation. The 245-kV breakers were the world’s first of its kind to switch a short-circuit current of 80 kA. The project included engineering, design, supply and delivery, commissioning, all associated control and protection equipment, and buildings for the substation. This projects upgraded the existing 138-kV lines to 230 kilovolts. The GIS helps provide additional load capacity and enhances safety and reliability by redundancy in the system design and earthquake resistance.

Norway benefits from an additional feed-in of electricity provided by wind and small hydro power plants

Statnett SF energy system operator | Sogndal substation, Norway  Sogndal substation is a key node point in Western Norway. It strengthens the Western Norway power grid, increases the electricity transmission capacity, and provides voltage support by installation of a Static Var Compensator (SVC). As a result, it ensures an additional feed-in of electricity and a redundancy capacity provided by wind and small hydro power plants. Siemens was responsible for the planning, delivery, and installation of nine bays for a 420 kV AIS, in  double bus, two breaker design, three bays for a 145kV AIS, in single bus, single breaker design. Furthermore the contract was comprising the connection of the existing 300kV transmission lines with the new 420kV substation and the design, delivery, and installation of a +/- 250 MVAr Static Var Compensator (SVC).

Downloads and support

Additional information

Here’s where you can download additional brochures and documentation and request further information on high-voltage substations.

Power Transmission Service

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White paper

Modern Subterranean Substations in GIS Technology

This paper outlines the opportunities and challenges that arise from the use of modern subterranean substations, which are considered a contribution to assuring an economical and environmentally friendly power supply. Examples of completed installations and projects under construction provide a wide overview of situations and solutions. Simply enter your contact details to download the white paper.   

In-depth information

Technical excellence at your fingertips

Siemens high-voltage substations incorporate the strong performance of one of the world’s leading engineering companies and one-stop supplier of power transmission products, solutions, and services.   If you want to learn more about the advantages of Siemens’ time-tested, proven solutions and to delve into all technical details, simply contact the Siemens Customer Support Center and have your individual questions answered directly by our experts.

The Power Engineering Guide is the comprehensive manual for transmission and distribution of electrical energy.

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