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Top performance meets superior environmental and safety standards

Furnace transformers as well as heavy-duty rectifier and converter transformers connect processes to the power grid. Their purpose is to supply a critical resource to energy-intensive industrial applications – high currents with very specific voltages. These transformers must meet rigorous requirements. Siemens ' expertise in design and precision manufacturing ensures customers enjoy top performance and efficiency in terms of both cost and energy. At the same time, units need to be extremely reliable in operation and environmentally sound while affording the highest level of safety for those working in their vicinity.


Heavy-duty powerhouses that withstand harshest ambient conditions

Siemens transformers are leveraged in very different environments, from mining to oil and gas extraction, from steel plants to chemical industries. Each area of application requires specific transformer designs to supply the right kind of power for very specific projects in very specific environments. Siemens transformers for all industrial environments. Their especially rugged designs withstand exposure to dirt, gases, short circuit forces, and high magnetic fields.


Siemens transformers built for industrial applications deliver extended voltage regulation ranges. They can provide extremely high currents and have the capacity to feed multi-pulse rectifier units to ensure low system perturbation. This allows them to withstand cyclic load and high thermal stress while remaining highly reliable. In addition, furnace transformers withstand frequent overcurrent and overvoltage caused by short circuits in the furnace or by tripped high-voltage circuit breakers.

Why Siemens Transformers

Design experience and market intimacy at your service

As a leading supplier for over six decades, Siemens not only brings more than 100 years of experience in transformer technology to its industrial transformers but a production and service network that spans the planet. This global network keeps response times short, ensures just-in-time delivery, and gives you the same extensive know-how and the same technology and quality wherever you are.    

Rich customization options and unique designs

Siemens Transformers translates individual customer requirements into unique premium-quality transformers with a reputation for superior reliability and an impressive service life. Siemens has developed a wide range of design options to ensure its tailor-made transformers cover all customer use cases.


Design options for high-current transformers for industrial applications

Specifications for voltage, power rating, ambient climate, network topography, and noise level are typical transformer criteria.
Further design options include:

  • Cooling and extreme-heat protection
  • Oil-directed cooling designs for high power densities in small installation places
  • Transducers – rugged technical designs for voltage regulation as an alternative to electrical parts
  • Defined earthing and electrical grounding to avoid loop currents
  • Direct or indirect voltage regulation
  • On-load or off-load tap changer
  • Compensated lead connection designs to decrease magnetic fields
  • Shielding designs to decrease the effects of high magnetic fields
  • Monitoring

Cross-benefitting from breakthrough innovations

Within its Global Technology Center, Siemens has dedicated two Centers of Competence exclusively to driving innovation in large and medium power transformer. As a result, Siemens transformers across the board benefit from design breakthroughs, even those originally achieved for other – sometimes more complex – transformer types. This ensures cutting-edge technology across the entire transformer portfolio.

Superior performance density in minimum-footprint designs

What makes Siemens transformers stand out in the market is the superior performance density they bring to especially compact and lightweight designs. 

Protect your transformer assets

SITRAM TDCM is Siemens’ advanced online monitoring system for transformers old and new. This cost-effective solution gives you online access to relevant transformer data, enables early fault diagnostic, and offers comprehensive prognoses and recommendations. 

Siemens Transformer Online Monitoring System transforms service into reliability

The impact of transformer outages on the process industries in which they are used can be severe because outage costs may not be limited to the cost of transformer repairs. In industrial applications, an outage may result in standstills and a total loss of production. Related costs can quickly rise to a level that affects even larger organizations. An effective way to minimize this risk is the continuous monitoring of key parameters during transformer operation. According to an independent study, online monitoring systems can detect 60% of all typical transformer errors before they occur.

The 5 top benefits of the Siemens TDCM sensor

  1. Evaluate and time replacements with better accuracy
  2. Identify incipient faults and take action to avoid costs of a high-impact failures
  3. Potentially reduce of insurance indemnity for defects
  4. Gain a better understanding of operative conditions and control
    to further decrease costs and the risks of faults
  5. Benefit from predictive maintenance and optimize the maintenance process

Benefits of Siemens Transformer Online Monitoring System

The Siemens online monitoring system for transformers incorporates the most advanced analytical technologies. It helps to effectively reduce failure risks while increasing the efficiency of maintenance during operation.



Remanufacturing transformer originals

When a transformer reaches the end of its lifecycle, it needs to be replaced to maintain the operation. Although there are ways to fast-track replacements, ordering, designing, building and even delivering a replacement transformer generally requires careful planning well ahead of its installation. Siemens experts work closely with customers to reliably remanufacture transformer originals. Customer can choose a 1:1 replica or opt for a new transformer that fits into the existing vault or chamber but offers greater capacity.



Same dimensions, higher power density                     


In steelworks especially, the notoriously small transformer chambers set challenging limits for capacity expansion. Thanks to extensive expertise in cooling designs and in handling high magnetic fields, Siemens is able to offer higher power density with much smaller real estate requirements than the competition.    


The factory acceptance test, which Siemens transformers undergo fully assembled in Siemens own test bays, includes tests against standards specified by the customer. 


These standards include but are not limited to:

  • ISO 9001, 14001 for certified plants
  • The certification according ISO 29001, a standard important for customers in the oil and gas industry, is a unique advantage of the Siemens transformer production site in Dresden.
  • IEC 60076-1 for power transformers
  • IEC 61378-1 for converter transformers and as an additional standard for transformers for industrial applications
  • IEEE Std C57.12 is a standard for general requirements for liquid-immersed distribution, power, and regulating transformers
  • IEEE Std C57.17 describes the electrical characteristics and mechanical requirements for arc furnace transformers. This is a standard relevant to customers located in the US.    

Transformers Types

Powering industries

Siemens designs and builds a wide range of tailor-made high-current electric arc furnaces, rectifiers, and converter transformers for applications in process industries where power is a key resource.

Electric Arc Furnace Transformers


Transformers for melting processes

AC EAF transformers are specifically designed to withstand the exceedingly severe conditions accompanying metallurgical steel melt processes in

  • foundries,
  • in secondary steelmaking,
  • in ferroalloy production.

Technical features

  • Ratings up to 300 MVA
  • Secondary voltage up to 2 kV
  • Electrode current for steel up to 120 kA
  • Electrode current for ferroalloy up to 180 kA


EAF design options

  • Direct or indirect regulation or booster
  • On-load or off-load tap changer
  • Oil- or vacuum-type OLTC, also reactor-type OLTC
  • Series reactor (built-in or separate) for long arc stability
  • Air- or water-cooled secondary bushing arrangements and designs
  • Internal secondary phase closure (internal closed delta)
  • Special magnetic shield designs – a Siemens specialty
  • OF- or OD-cooling


Heavy-Duty Rectifiers


Transformers electrolysis and smelting

Heavy-Duty Rectifiers (HDR) are used for

  • industrial processes, which require a significant direct current (DC) supply. Typical areas of application are aluminum electrolysis or smelting operations.
  • high secondary currents, together with the harmonic currents generated by the rectification systems.


Technical features

  • Ratings up to 225 MVA
  • Secondary voltage 2 kV to nearly 0 V depending on the application


HDR design options

  • Direct or indirect voltage regulation 
  • Double-star or bridge connection
  • Double-tier design and/or keel line arrangement
  • Double-tier with or without intermediate yoke
  • On-load or off-load tap changer
  • Filter connection or filter winding
  • Additional phase-shifting windings for 12-pulse or higher pulse systems
  • Interphase reactor, saturable reactors (transductors)
  • Air-cooled secondary bushing arrangements and designs
  • Numerous different vector groups and phase shifts    

Converter Transformers


Transformers for large-drive industrial applications

Converter transformers

  • supply the input for variable-speed drives, e.g. for large-scale industrial drives, pump stations, rolling stock in mining applications, or blast furnaces.
  • allow multi-pulse (up to 36) rectifier operation.


Technical features

  • Ratings up to 200MVA
  • Secondary voltage between 800V - 36kV, depending on the drive
  • Additional winding to filter harmonics
  • Combination with a frequency converter


Design options

  • Double-tier or multiple-tier design
  • On-load or off-load tap changer
  • Filter winding and/or earth screen
  • Various vector groups and phase shifts
  • Variable-speed drive design
  • ATEX certification
  • Operation in harsh environment
  • Alternative insulation liquids    

Download and Support

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.

Contact the Energy Support Center

Energy customer Support

+49 180 524 70 00

+49 180 524 24 71


Freyeslebenstrasse 1

91058 Erlangen


Energy customer Support

+49 180 524 70 00

+49 180 524 24 71


Freyeslebenstrasse 1

91058 Erlangen


Ready to meet any challenge

Solving the specific challenges of each customer, Siemens Transformers brings expertise, superior technical design, and rigorous dedication to quality to transformers for every kind of application. As a result, customers benefit from transformers with trademark low failure rates, exceptionally long service life, and a track record of cost-saving operation.



Active-part cooling for mass-optimized replacement transformers with increased ratings

150 MVA

max. ratings capacity    

0 kA

max. electrode current for steel    

0 kA

max. electrode current for ferroalloy

Mastering one of the most complex transformers ever built

0 ratings

46.8 / 4x16.5 / 20 (filter) MVA    

0 ratings

132.0 / 4x 0.509 / 23.7 kV    

15000 kA

current x4

Landmark safety and top performance


pulse converters fed by 4 low-voltage systems in double-tier


Atex certification for ex zone

0 kV

rating with 4x 2.0kV ± 5 % (NLTC) and 16/4x4MVA

Request a quote for a high-current industrial application transformer

Do you need a tailored transformer to solve your specific industry challenges? Talk to us and we will find the right design to meet your specs.