How Transformers Are Powering Data Centers

by Todd Benadum
February 9, 2026
Dry Type Transformers

Continuous and precise power is nonnegotiable for data centers. Even a brief disruption can trigger failures across thousands of servers, corrupting critical data and costing organizations thousands of dollars per minute in lost revenue. The transformers that step down voltage and distribute power throughout these facilities must deliver reliable and efficient performance.

Poor transformer efficiency generates excess heat that cooling systems must remove, resulting in wasted energy and increased operating costs. Uptime is equally critical, as transformer failures can turn off entire sections of a facility even when redundant power systems are in place. Choosing the best-suited transformer determines whether the entire facility can meet its reliability requirements.

Tier IV facilities set the highest reliability standard, allowing only minutes of downtime annually compared to hours for lower-tier classifications. These strict reliability requirements shape every decision about electrical infrastructure. Understanding how transformers function within data center power systems helps operators select equipment that meets these demanding standards.

Power Distribution in Data Centers

Data center tier classifications define redundancy requirements. Tier III facilities need N+1 redundancy, where every critical component, including transformers, has at least one backup. Tier IV facilities require 2N configurations, featuring two fully independent power systems capable of handling the entire facility load.

Power flows through data centers in a two-stage transformation process from the utility grid to server racks. Utility companies deliver electricity at medium voltage levels — typically ranging from 10 kV to 35 kV — to minimize transmission losses over long distances. IT equipment operates at much lower voltages, requiring transformers to bridge this gap.

The first stage occurs at the service entrance, where medium-voltage transformers step down incoming utility power to intermediate distribution levels. The second stage happens closer to IT equipment, where transformers in power distribution units (PDUs) perform the final conversion to usable voltages. Medium voltage transformers in the 500 kVA to 3,750 kVA range, with primary voltages from 2,400 volts to 34,500 volts, can typically meet these requirements.

Oil-filled padmount transformers are ideal for outdoor applications at the main service entrance where utility power enters the facility. Dry type transformers handle indoor distribution systems closer to IT loads due to their safer operation in occupied spaces. Selecting the appropriate transformer type for each stage impacts system reliability and long-term efficiency.

Powering Data Centers at the Service Entrance

Padmount transformers handle the first voltage transformation stage at outdoor substations. These oil-filled systems step down utility-level voltage to lower levels that internal distribution systems can manage. Liquid cooling effectively dissipates heat, enabling these transformers to handle the continuous, high-capacity loads that data centers need around the clock.

Tamper-proof lockable doors secure outdoor installations. These enclosures protect equipment from unauthorized access while maintaining accessibility for scheduled maintenance and emergency repairs. Padmount transformers withstand harsh weather conditions while delivering reliable performance for decades.

Other key features that support 24/7 data center operations include:

Zero-downtime fluid testing: External drain valves enable oil analysis without opening the main compartment or interrupting power delivery.
Dead front and live front configurations: Dead front eliminates exposed high-voltage connections for enhanced safety, while live front provides standard configurations for controlled-access substations.
Loop feed and radial feed configurations: Loop feed offers enhanced reliability through dual utility feeds, while radial feed reduces costs for facilities with robust backup generation.
Copper or aluminum winding options: Engineers can match transformer specifications to project requirements and budget.

Transformers for Interior Distribution

Dry type transformers perform the second transformation stage inside data center buildings. These air-cooled systems integrate into PDUs throughout server halls, converting medium voltage to the precise levels required by IT equipment for stable operation. Fire safety and ease of indoor installation drive the preference for dry type units.

Installing transformers near their loads reduces voltage drop and energy losses in distribution cables. This proximity improves power quality at server racks while contributing to lower power usage effectiveness (PUE) scores. Compact designs fit within the space constraints of today’s data center layouts, where every square foot carries value.

Features that boost performance under continuous full-load operation include:

100% copper windings: Superior electrical conductivity and heat dissipation extend transformer life in high-duty-cycle applications where units run at or near rated capacity.
Sheet winding methods: Mechanical strength withstands the electrical stresses of continuous full-load operation without degradation.
Disc windings for high-voltage units: Units rated 25 kV or higher use disc windings to manage electrical stress more effectively than conventional techniques, reducing the risk of insulation breakdown over the course of decades of service.
Nomex insulation: Fire-resistant insulation provides safe operation without liquid coolants, allowing closer installation to IT loads.

Efficiency and Long-Term Value

Transformer losses increase PUE scores and overall operating costs. When transformers waste energy as heat, cooling systems must work harder to remove that heat from server halls, compounding the inefficiency.

Transformers exceeding Department of Energy efficiency standards reduce energy losses and heat generation throughout their operational life. Lower operating temperatures decrease HVAC loads, with efficiency gains compounding over a service life exceeding 35 years with proper maintenance.

Installing a high-quality transformer from a reliable supplier once and operating it for decades minimizes the disruption and expense of premature replacements. While servers and networking equipment require replacement every few years, electrical infrastructure must provide decades of reliable service. Prioritizing long-term reliability and total cost of ownership over the lowest initial price delivers better value across the equipment’s lifespan.

Proven Reliability for Data Center Transformers

ELSCO Transformers manufactures medium-voltage oil-filled padmount and dry type transformers in the 500 kVA to 3,750 kVA range, covering capacity requirements from edge facilities to hyperscale operations. Our transformers are engineered specifically for the continuous duty cycles and reliability requirements that data center applications demand. Over a century of transformer manufacturing experience informs every design decision we make for mission-critical infrastructure.

Key differentiators that set ELSCO apart from other manufacturers include:

Zero-failure record: Our dry type transformers have achieved zero failures since 1988, thanks to our superior expertise, meticulous hand assembly and rigorous quality control.
Premium-grade materials: Laminated steel cores, 100% copper windings and Nomex insulation deliver long-term reliability under continuous operation.
Industry-leading warranties: Our transformer warranties provide five-year coverage on new dry type units for indoor installations and one-year coverage on oil-filled padmount transformers backed by our proven track record.
Emergency replacements: Our emergency transformer replacement services enable us to ship in-stock units within 24 to 48 hours, depending on the required modifications.

Learn More About Transformers for Data Centers With ELSCO

If you need a high-efficiency system for your data center facility, the professionals at ELSCO Transformers can guide you. Besides offering oil-filled and dry type units for a wide range of industries, we provide a full range of services for all your operational needs, including customization, retrofitting, repairs and bus work.