How are Siemens Energy power transformers tested?

Each transformer undergoes rigorous factory acceptance testing (FAT), including routine, type, and special tests, to ensure compliance with international standards, customer requirements and reliable performance.

How much does a power transformer cost?

Costs depend on design complexity, specifications, and project requirements. Siemens Energy provides tailored solutions with transparent pricing upon request.

What causes a power transformer to fail?

Common causes include insulation breakdown, overheating, moisture, mechanical stress and mal operations. Siemens Energy mitigates these risks through design competence, digital monitoring and customer training.

What types of insulation fluids are used?

Siemens Energy transformers support mineral oil, natural and synthetic esters, and re-refined oils — selected based on performance, safety, and environmental criteria.

How do power transformers improve grid stability and efficiency?

They regulate voltage, balance loads, and reduce transmission losses , enabling stable, efficient, and resilient grid operation.

How do Siemens Energy transformers support the energy transition?

By enabling renewable integration, HVDC transmission, and digital grid management, Siemens Energy transformers play a key role in decarbonizing global energy systems.

What voltage and power ratings are available?

Siemens Energy offers fully customized designs across all globally requested ratings and voltage levels, ensuring solutions for every grid and application.

What is the typical service life and post-purchase support?

Siemens Energy power transformers are designed for decades of reliable operation. We provide comprehensive lifetime support — starting with feasibility studies and design, through delivery and commissioning, and continuing with maintenance, upgrades, digital monitoring, and advanced services that go beyond traditional support. Our global service network.

Power Transformer Solutions

Siemens Energy’s power transformers are essential building blocks of resilient and efficient power grids. Backed by decades of engineering excellence and a global manufacturing footprint, the transformers deliver reliable performance under the most demanding conditions. Each unit undergoes rigorous testing to meet the highest quality standards — ensuring long service life, grid stability, and operational efficiency.

As energy systems evolve toward decarbonization, decentralization, and digitalization, power transformers must meet increasingly complex demands. Siemens Energy offers tailored transformer solutions that support grid modernization, renewable integration, and cross-border energy exchange — all while ensuring reliability and efficiency.

Every Siemens Energy power transformer is a custom-engineered unit, designed and manufactured according to specific customer requirements. This bespoke approach ensures optimal performance, seamless grid integration, and long-term value across diverse applications.

Rendering of a Siemens Energy large power tansformer

Siemens Energy’s large power transformers are the backbone of high-capacity transmission and critical infrastructure projects worldwide. Engineered for maximum efficiency, durability, and grid stability, they ensure reliable energy flow across vast distances and complex networks. Whether reinforcing national grids or enabling intercontinental power corridors, each transformer is custom-designed to meet stringent technical and environmental standards, supporting the global energy transition.

Rendering of a Siemens Energy medium power transformer

Medium power transformers are built for flexible deployment in transmission and distribution networks, ensuring reliable performance across diverse applications. They are ideal for grid interconnections, industrial facilities, and renewable energy hubs. Each unit is custom-engineered, integrating features such as advanced cooling systems, eco-friendly insulation fluids, and digital monitoring for smarter operations.

Model of a Siemens Energy phase-shifting transformer

Model of a Siemens Energy HVDC transformer

Model of a Siemens Energy mobile resilience transformer

Siemens Energy’s mobile resilience transformers provide rapid-response solutions for grid emergencies, temporary substations, or disaster recovery.. Siemens Energy designs mobile units for fast deployment, ensuring reliable power supply during outages or infrastructure upgrades. These custom power transformers are engineered for flexibility, transportability, and high performance under time-critical conditions.

When selecting the right transformer for a specific application, understanding the key differences between transformer types is essential. The table below compares Medium Power Transformers, Large Power Transformers, and HVDC Converter Transformers across critical specifications such as voltage range, power rating, cooling systems, and typical applications. Despite their differences, all transformer types share common features like customized design, advanced digital monitoring, and flexible insulation options —ensuring reliable performance across diverse energy systems.

The Pretact® concept by Siemens Energy is designed to maximize the resilience of power grids through a modular system of preventive and protective features. It safeguards transformers and high-voltage equipment from operational disruptions, natural disasters, and unexpected outages. Additionally, highly adaptable plug-and-play mobile resilience units ensure rapid response during emergencies or scheduled maintenance—supporting a stable and uninterrupted power supply.

Siemens Energy’s Pretact® Ecosafety is the world’s first substation concept that integrates proven and newly developed technologies to elevate environmental protection, health, and safety. This innovative solution is designed to minimize the risk of fire and explosions, enhancing both resilience and sustainability. By reducing potential harm to nature and human life, Pretact® Ecosafety sets a new standard for safe and future-ready substations.

Siemens Energy is deeply committed to decarbonizing the energy sector and continuously advancing sustainability in both the supply chain and the core components of transformers. Through close collaboration with suppliers and customers, the company develops step-by-step solutions that reduce CO₂ emissions across the entire lifecycle. In parallel, Siemens Energy is actively working toward a circular economy, aiming to set new industry benchmarks for environmental responsibility and resource efficiency.

Power transformers are essential for the reliable transmission and distribution of electricity. Siemens Energy takes protection to the next level: with advanced materials and innovative designs, these transformers and reactors are not only resilient against extreme weather and grid fluctuations but also engineered to withstand ballistic attacks. This ensures the physical security of your assets and guarantees a stable, future-ready energy supply.

Siemens Energy offers a versatile range of insulation fluids to meet diverse environmental and operational requirements. In addition to conventional mineral oil, natural esters, synthetic esters, and re-refined oils are provided. Each fluid type offers specific benefits depending on the application—such as improved fire safety, reduced environmental impact, or support for decarbonization goals. This flexibility allows transformer solutions to be customized for performance, sustainability, or regulatory compliance.

DC Compensation: The smart solution for proative transformer protection

Boost transformer reliability with Siemens Energy’s advanced DC compensation technology. The compact, high-efficiency solution is engineered to protect transformers from harmful DC bias in the power grid. As shown in the video, this innovative approach addresses challenges like asymmetric loading using a streamlined method that outperforms traditional solutions such as DC blockers, noise protection walls, and costly transformer replacements.

By enabling proactive DC bias management, the solution enhances transformer resilience, supports grid stability, and contributes to long-term asset performance. Explore the materials below to learn how this DC application can help you future-proof your transformer infrastructure.

DC bias occurs when direct current (DC) infiltrates an alternating current (AC) system, potentially causing distortion and inefficiency. Understanding and addressing DC bias is crucial for maintaining the integrity and performance of electrical systems, particularly transformers.

Watch the DC bias video

For a clear understanding of DC bias, watch this short explainer video. Tap the ▶️ button to start watching.

Identify DC bias quickly using the free Direct Current Detector app. Measure noise levels on your smartphone to ensure your transformers remain in optimal condition.

Learn more about DC detection
For detailed information on how the app works, check out the informative flyer.

Refine your approach to DC Bias with our focused OnePager. Essential technical insights, distilled for clarity and impact.

Proactive DC bias protection for transformers
Learn how to effectively overcome DC Bias challenges in your electronic systems. Our recent article offers exclusive insights for professionals seeking reliable solutions.

Factory testing and quality assurance
All units are subjected to extensive factory acceptance testing (FAT), including routine, type, and special tests in accordance with international standards (e.g. IEC, IEEE). The test facilities are equipped to handle high-voltage, high-power testing for even the largest transformer designs.
On-site commissioning and diagnostics
Siemens Energy provides expert support during installation and commissioning, including on-site testing, oil analysis, and partial discharge measurements. The mobile diagnostic units ensure fast and accurate assessments, even in remote locations.
Lifecycle services and maintenance
To maximize transformer lifespan and performance, tailored maintenance programs, condition monitoring, and refurbishment services are offered. Predictive analytics powered by Sensformer™ technology enable proactive service planning and minimize downtime.
Global service network
With service hubs and experts located worldwide, Siemens Energy ensures fast response times and reliable support throughout the entire lifetime of your transformer — from feasibility studies, offer preparation, and design through delivery and factory acceptance testing (FAT) to decades of operation. The global service network provides peace of mind by helping you maintain performance and maximize the long-term value of your assets. In the U.S. and Italy. Siemens Energy also operates flexible deployment units that can be quickly mobilized to reduce the risk of unplanned downtime and ensure rapid support when it’s needed most.

Siemens Energy is a globally recognized manufacturer and supplier of high-voltage power transformers, operating an extensive engineering and production network across multiple continents. Collaborations with joint ventures and licensed partners further expand the global footprint, ensuring flexibility and scalability to meet evolving grid demands. Harmonized design principles and standardized engineering processes across all plants guarantee consistent quality and enable customized solutions for power networks, renewable integration, and critical infrastructure. With more than a century of experience, Siemens Energy combines proven reliability with continuous innovation and advanced research—setting industry benchmarks for performance and efficiency.

With a presence in over 90 countries, Siemens Energy transformers support power systems in all climate zones—from renewable energy hubs and HVDC corridors to urban grid expansions. The portfolio includes solutions for transmission, interconnection, and decentralized energy systems, seamlessly integrating with distribution transformer offerings for full grid coverage.

Whether you're looking for a custom-built transformer or a scalable solution for complex grid environments, Siemens Energy delivers future-ready transformer technology backed by decades of global expertise.

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A power transformer is a static electrical device that transfers energy between circuits at different voltage levels using electromagnetic induction. It plays a key role in AC power grids by enabling efficient transmission and distribution of electricity—from generation to consumption. Modern power transformers are designed to handle high electrical stress and often include on-load tap changers (OLTC) to regulate output voltage and maintain grid stability, which is increasingly important with the expansion of renewable energy sources.

A power transformer’s main role is to convert voltage levels in the power grid—stepping up voltage for efficient long-distance transmission and stepping it down for safe local distribution. This process helps to minimize energy losses, ensure grid stability, and enable the integration of renewable energy sources. By adapting voltage to the needs of each grid segment, transformers are essential for a reliable and efficient energy supply.

Specification	Medium Power Transformer	Large Power Transformer	HVDC Converter Transformer
Voltage range	Up to 300 kV	Up to 1,100 kV	± 1,100 kV
Power rating	Up to 250 MVA	Up to 1,300 MVA	Up to 750 MVA
Cooling system	ONAN/ONAF	ONAN, ONAF. ODAF, ODWF	OFWF, ODAF, ODWF
Applications	Grid, Industry, Renewables	Transmission, Interconnectors	HVDC Classic & HVDC Plus

Power transformers

Siemens Energy power transformers: Engineered for reliability, designed for the future.