model of a Siemens Power Transformer

Power Transformers

Specializing in reliable solutions with maximum efficiency and availability

Transformers from Siemens Energy support grid operators in giving their customers state-of-the-art equipment and energy that is safe and affordable.

Reliable, long-lifecycle solutions built to customer requirements

For more than a century, power suppliers and industrial companies have relied on Siemens Energy for its reliable and efficient power transformers. Almost all of them, ranging from power ratings from 20 MVA to units well above 1,000 MVA,and 20 kV to 1,100 kV are tailor-made.

Siemens Energy offers a complete chain of services – from consulting to design, manufacture and transport to commissioning and Transformer Lifecycle Management (TLM). As one of the leading transformer manufacturers worldwide, we offer a tight and responsive competence and service network in more than 190 countries in the world.

Precision engineering architecture

Precision, utmost attention to detail and design according to state-of-the-art standards in manufacturing ensure the high efficiency, long lifecycles, and low failure rates of our power transformers.

Siemens Energy's experience with custom-built units has led to a highly sophisticated design process that offers flexibility within a certain standardization frame while giving customers an economically efficient customization solution. The enhanced customization process offers additional advantages: Its highly-evolved modular architecture keeps manufacturing and maintenance efficient and cost saving.

Precise core manufacture ensures low losses and minimal no-load noise

The iron core forms the central element of a power transformer. High-grade, cold-rolled and laser-treated metal sheets with thicknesses of 0.3 mm or less are precision-cut with computer-controlled machines, to ensure compliance with even the smallest tolerances. The individual sheets are then manually or computerized assembled into cores. The »step-lap« technique ensures superior flux distribution at the joints, resulting in exceptionally low losses and minimal no-load noise. Siemens is one of the few transformer manufacturers able to assess material losses during the cutting of core metal sheets. This way, Siemens can verify the quality of the material and ensure the quality is up to the standard the customer expects.

winding of power transformer

Windings for high mechanical strength and long operational reliability

Transformer windings are subject to continuously high electrical and mechanical loads. Disk and cylindrical coils with transposed conductors of copper wire guarantee high mechanical strength and long operational reliability. Disk coils for high voltages consist of continuously wound coils. The continuous winding keeps soldering points to a minimum. Precise control systems ensure constant contact pressure and winding tension while experienced coil winders monitor every working step. Multi-layer windings for low voltages consist of concentrically superimposed cylindrical coils separated by axial oil ducts.

Safe adjusting of voltage to system conditions   

Siemens transformers allow you to safely adapt the voltage to grid conditions. It can either be changed in the deenergized state by means of a deenergized tap changer or adjusted in steps under load using on-load tap changers. On-load tap changers and optionally deenergized tap changers are fitted with a motorized drive and can be controlled either locally or remotely.

The tank – light, structurally sound, and leak-proof

High-grade, quality-assured tanks define the appearance of our transformers. This protective shell accommodates the core-and-winding assembly and the insulating oil. Together these often weigh several hundred tons. The tank should therefore not add too much extra weight, but at the same time it has to be structurally sound and leakproof, and must withstand mechanical stresses. First-class corrosion protection is therefore a basic requirement for long tank life.

The core-and-coil assembly of the transformer consists of core, windings, tap switches, and connecting cables. Special attention is paid to the mechanical stability of the windings. A joint press ring for all windings on a core limb minimizes axial shear forces. The assembly dries under vacuum at 130 degrees Celsius. Bolted connections are tested and secured right after drying and just before the assembly is installed in the tank, even though, the assembly is still at a temperature of over 100°C. To ensure a long service life, the transformer is then filled with insulating oil.

Power Transformer in Testing Laboratory

Once motor drive, control cabinets, bushings, monitoring equipment, etc. are installed, the power transformer remains in an unenergized state until it's time for final testing and inspection at our very own testing facilities.

Daily savings

Services and products from Siemens Energy ensure daily savings and strong investment security for customers. Our regional manufacturing plant setup ensures savings in capital expenditures and our specialists are enhanced with broad experience and in-depth knowledge required for creating custom unit designs. The benefits of minimized failure rate and losses, improved power quality with state-of-the-art transformer applications, low-noise transformers and monitoring systems for preventive maintenance, on the other hand, translate into savings in operational expenditure.

Operators can leverage Siemens Energy transformers to increase capacity utilization and to optimize grid operation. A reactor, for example, can transmit more energy over existing lines, or a phaseshifter can be used to optimize load flow. Siemens Energy not only builds retrofits with latest-technology transformers to replace old units but also offers interesting project financing solutions. 

Minimized risk of failure

A reliable power supply is key for business success in energy-intensive industries. Risk management strategies typically range from alleviating the impact, reducing threat probability to transferring all or part of the threat to another party. The choice of strategy is based on the description of the risk they are dealing with. Mean time between failure (MTBF) is one key performance indicator in risk assessment.

Power transformers from Siemens Energy can be integrated into any kind of power management system. In addition, Siemens Energy offers a comprehensive Pretact® solution, designed to maximize grid availability by minimizing the consequences of both unplanned outages and planned outages. 

Making the most of its decades of experience in manufacturing and managing low voltage to extreme high voltage levels, our portfolio offers highly reliable transformers, from distribution to HVDC transformers, with minimized risk of failure and maximized availability.

Manufacturers generally provide reliability indices – “Failure Rate” (FRe) as well as lists of MTBF – which are calculated using standard industry targets. But there is no “one-size-fits all” strategy to picking such targets. Calculating reliability indices and metrics is most useful when there is an actual target level of performance to be met. 

The average failure rate of a transformer changes over its lifetime. Even slight deviations can make a big difference – maybe not in the first years of service, but surely further ahead in its lifecycle. Incorporating reliability indices in a congruent risk management framework is crucial to business success, and it is important to consider the limitations of risk indices. Siemens Transformers supports customers in understanding and calculating reliability, not least because their transformers have a unique track record of high reliability, from in-time delivery to safety, from quality of product to transparent contacts and support.

Core of a power transformer

Transformer Lifecycle Management (TLM) is a service concept for all transformers in your network, regardless of age, manufacturer, or power. It lets you plan expenditures and control the timing of new investments. It helps to avoid unplanned outages and minimize planned downtimes. And TLM™ supports you in reducing your environmental footprint while maximizing transformer availability.

We bring transformer service to you

Your transformers need to operate reliably and without interruption. Siemens' TLM™ service concept helps you make the most of your fewer and increasingly shorter windows of opportunity even for planned service interruptions. The TLM™ answer to the problem are technologies and methods that are as mobile as our experts. From oil-drying systems to high-voltage testing stations, TLM™ mobile repair workshops support you on-site. They complement the services provided by the Siemens’ repair facility – they’re fast, flexible, and can be integrated in your operations.

We manufacture Siemens power transformers in a total of 14 transformer factories on four continents. Each one of these production plants has a different focus in terms of research and development. Our network of factories ensures that our customers worldwide profit from the special skills and solutions of all individual locations. Quality is always to European standards, regardless the manufacturing location.

Customer advantages

  • Prompt preparation of bids
  • Optimized, consistent end-to-end project management
  • Noticeably shorter production and delivery times
  • Very high delivery reliability
  • Flexibility and reliability thanks to backup factories
  • Fast, standardized documentation
  • Just-in-time delivery

Harmonized design, globally standardized design guidelines, and standard IT programs for all plants ensure that our customers always receive the best possible product, no matter which Siemens factory they purchase it from.

Alternative insulation fluids

By replacing older applications with more powerful transformers using the latest technology substantially reduces the overall carbon footprint of a transformer unit.

Siemens Energy offers insulation fluids as natural and synthetic environmentally friendly ester, including reactors, phase shifters, and HVDC applications.

Benefits of ester insulation

  • High flash- and fire point for increased safety
  • Readily biodegradable fluid for extended environmental protection
  • High moisture tolerance for a long lifetime
  • Possibility to increase transformer loading
  • Synthetic ester: low pour point (-56°C) allows operation in cold climates
  • Lower costs thanks to decreased risk of fire and longtime outages due to hazardous failures.

Certified quality standards

A strong factory network around the globe creates leading transformer technology and pre-manufactured components. Our gobal footprint of transformer experts, familiar with both local and international requirements, also ensures customers enjoy fast response times and on-time delivery. In committment to quality without compromises, the quality management system used across all plants manufacturing power transformers complies to DIN ISO 9001:2015.

To meet public local content requirements, Siemens Energy also enables and supports local transformer manufacturers to produce transformers based on our technology. However, to ensure a consistently high transformer reliability, we implement in-house prototype design and manufacturing.

Power transformers for every challenge

Learn more about latest references of our power transformers

Our power transformers are manufactured in 14 factories in various countries for the reliable operation all over the world. Built to comply national and international standards according to customer needs, including excellent customer service - wherever you are.

Make use of our services

For your convenience, we have gathered relevant downloads in one spot. If your question is still unanswered, please feel free to contact our Energy Support Team.

Brochure downloads

Alternative insulation fluids
PDF (1 MB)
Benefits STL
PDF (804 KB)
Trusted partner in the energy transition
PDF (934 KB)

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