Varelen delivers custom-engineered transformer solutions designed for hyperscale, colocation, and modular data centers. Our products meet the stringent requirements of EPC contractors, electrical consultants, and system integrators, offering continuous 24/7 operation, harmonic mitigation, and parallel redundancy support.

In modern data centers, uptime and power quality are mission-critical. Varelen transformers are optimized to handle non-linear loads, high harmonic currents, and dynamic operating conditions, enabling reliable and energy-efficient operation.

Why Data Centers Require Specialized Transformer Solutions

Data centers present unique challenges that standard distribution transformers cannot meet:

• High harmonic currents from UPS systems, VFDs, and server power supplies

• Continuous 24/7 operation, with near-zero tolerance for downtime

• Redundancy requirements, including N+1, 2N, and 2(N+1) configurations

• Thermal and noise constraints, especially for indoor installations

• Scalability and future expansion for hyperscale or modular deployments

• Energy efficiency and sustainability mandates for ESG compliance

Varelen’s transformers address these challenges by:

• Supporting K-factor ratings for harmonic loads

• Ensuring continuous full-load operation without overheating

• Optimizing impedance for parallel transformer configurations

• Reducing load and no-load losses for energy efficiency

• Offering modular designs for scalable deployments

Formula 1 – Thermal Rise under Load
For a transformer with rated load Irated, ​ and winding resistance , the temperature rise ΔT  approximated as:

 ​

where  θamb​ is ambient temperature, and  ΔT rated​ is the rated temperature rise.

Transformer Solutions for Hyperscale, Colocation, and Edge Data Centers

Varelen provides tailored transformer solutions for different data center types.

Hyperscale Data Centers

• Medium-voltage transformers: 10kV–66kV

• Parallel operation and redundancy optimized

• High short-circuit strength for mechanical stability

• Advanced thermal design for continuous 24/7 load

• Optional amorphous metal cores to reduce no-load losses by up to 70%

Example Case – Hyperscale Campus 50MW

Colocation Data Centers

• Dry-type cast resin transformers

• K-rated harmonic mitigating designs

• Compact indoor footprint

• Low noise (<60dB) for office-proximate environments

Engineering Insight: For non-linear loads, K-factor rating reduces winding overheating by a factor proportional to harmonic content.

Formula 2 – K-Factor Rating

 ​

where Ⅰh ​ is the RMS current of harmonic $h$, Ⅰ1​ is the fundamental RMS current.

Edge and Modular Data Centers

• Pad-mounted dry-type or oil-immersed transformers

• Rapid manufacturing and delivery

• Integrated monitoring and protection systems

• Designed for future expansion in modular facilities

Scenario: A modular 5MW edge data center requires a 10kV/0.4kV transformer capable of handling sudden load increases up to 120% rated capacity. Varelen’s design ensures <80°C hotspot rise and fully complies with IEEE C57.12.90 testing.

Medium Voltage Transformers for Data Center Substations

Substations require transformers with high reliability and precise voltage regulation.

Varelen offers:

• Primary voltages: 10kV, 13.8kV, 22kV, 33kV, 36kV

• Capacity up to 40MVA

• Cooling types: ONAN, ONAF, hermetically sealed

• Optimized no-load and load-loss design

• Enhanced short-circuit withstand capacity

Design Table – Medium Voltage Substation Transformer

Voltage Regulation Formula:

where Vnl​ = no-load voltage, Vfl​ = full-load voltage.

Harmonic Mitigation and K-Rated Transformers

High-density data centers produce non-linear loads that damage standard transformers.

Solutions include:

• K-rated transformers (up to K20)

• Zigzag phase-shifting transformers

• Delta-wye harmonic mitigation

• Oversized copper windings and high-class insulation (155°C / 180°C)

• Advanced thermal modeling for harmonic heat losses

Case Study – AI Data Center

• Load: 10MW

• UPS THDi: 28%

• Varelen K13 transformer reduced hotspot temperature by 18°C, maintaining <120°C maximum winding temp, extending insulation life by 35%.

Energy Efficiency and Sustainability

Efficiency is critical for PUE and operational cost reduction.

• Optimized winding and core design reduces load/no-load losses

• Optional amorphous cores reduce no-load loss up to 70%

• Lower operating temperature increases transformer lifespan

• Supports ESG initiatives and reduces carbon footprint

No-load Loss Comparison Table

Engineering Consultation and Lifecycle Support

EPC engineers need predictive maintenance and lifecycle support:

• Online load and temperature monitoring

• Oil condition monitoring (oil transformers)

• Remote diagnostics integration

• FAT, SAT, and commissioning support

Case Insight: For a 33kV/0.4kV N+1 redundancy substation, Varelen provided parallel transformer impedance analysis, reducing circulating currents by 30% during simultaneous startup loads.

Custom Engineering Services for EPC Projects

Varelen supports:

• Busbar and connection customization

• Impedance matching for parallel transformers

• Short lead-time and fast-track options

• Compliance with IEEE, IEC, and project-specific standards

Example – Hyperscale Campus 50MW

Request a Data Center Engineering Proposal

EPC contractors, electrical consultants, and system integrators can submit project specifications for a custom proposal.

Required Inputs:

• Company & contact info

• Project location & capacity

• Voltage & redundancy requirements

• Single-line diagram (optional but recommended)

• Required delivery date

CTA Examples:

• “Submit Your Single-Line Diagram for Review”

• “Request a Custom Data Center Transformer Proposal”

• “Speak Directly with a Data Center Project Engineer”