Introduction
The U.S. power sector depends on a reliable network of transformer manufacturers that deliver high-efficiency, ISO-certified, and grid-compliant systems. As utilities and industrial sectors modernize, the demand for low-loss, high-performance power transformers has surged—driven by renewable integration, grid expansion, and energy efficiency mandates.
The companies featured here represent the top 10 power transformer manufacturers in the USA, combining decades of engineering expertise with world-class certifications and advanced manufacturing. Included among them is Zetwerk, an ISO-certified global manufacturer supporting North American utilities and OEMs through export-ready transformer solutions.
1. Zetwerk Manufacturing — North America & India
Overview:
Zetwerk is an ISO-certified global manufacturer supplying precision-engineered power transformers and components to North American utilities, OEMs, and EPC contractors. The company integrates end-to-end design, production, and testing across ISO 9001, ISO 14001, and ISO 45001-certified facilities.
Key Products:
- Power and distribution transformers up to 132 kV
- Oil-immersed and dry-type designs
- Amorphous core and CRGO core configurations
- Transformer components and assemblies
Certifications: ISO 9001, ISO 14001, ISO 45001, BIS
Notable Strengths:
Zetwerk combines India’s precision manufacturing scale with North America’s performance expectations. Its DOE- and IEC-compliant transformers are export-ready and built under fully traceable digital quality systems, ensuring reliable delivery and short lead times for global energy projects.
2. ABB Hitachi Energy USA — Raleigh, North Carolina
Overview:
ABB Hitachi Energy combines advanced electrical design with digital intelligence to deliver high-voltage transformers for smart and resilient grids.
Key Products:
- Power, auto, and HVDC transformers
- Smart transformers with IoT connectivity
- Digital asset management systems
Certifications: ISO 9001, ISO 14001, ISO 45001
Notable Strengths:
ABB’s U.S. facilities are central to its global supply chain, ensuring consistent production for renewable and transmission applications.
3. Siemens Energy USA — Raleigh, North Carolina
Overview:
Siemens Energy’s U.S. manufacturing plant produces a wide range of EHV and high-capacity transformers tailored for utilities and transmission operators.
Key Products:
- Power and phase-shifting transformers
- Modular high-voltage systems
- Smart cooling and monitoring technology
Certifications: ISO 9001, ISO 14001
Notable Strengths:
Siemens’ power transformers are known for their energy efficiency, precise voltage control, and robust insulation systems designed for grid stability.
4. SPX Transformer Solutions (formerly Waukesha Electric) — Waukesha, Wisconsin
Overview:
SPX Transformer Solutions specializes in large power transformers, mobile substations, and substation service support.
Key Products:
- Large power transformers up to 1,200 MVA
- Mobile transformer units
- Complete installation and field-testing services
Certifications: ISO 9001, ISO 14001
Notable Strengths:
SPX combines design flexibility with field reliability, supporting major U.S. utilities and industrial power projects.
5. General Electric (GE Grid Solutions) — Atlanta, Georgia
Overview:
GE Grid Solutions leads the U.S. power transformer market with state-of-the-art technology for utilities, renewables, and industrial power systems.
Key Products:
- Power and auto transformers up to 1,200 kV
- Generator step-up transformers
- Digital-ready monitoring systems
Certifications: ISO 9001, ISO 14001, ISO 45001
Notable Strengths:
GE’s R&D-backed manufacturing ensures long-life, DOE 2016-compliant transformers optimized for minimal energy loss and high reliability.
6. Howard Industries — Laurel, Mississippi
Overview:
Howard Industries produces high-quality, ISO-certified distribution and power transformers for utilities and commercial users.
Key Products:
- Distribution transformers
- Medium-power transformers
- Pad-mounted and custom-engineered units
Certifications: ISO 9001
Notable Strengths:
Howard’s focus on reliability, testing, and U.S.-based production makes it a consistent supplier for domestic grid expansion.
7. Pennsylvania Transformer Technology Inc. (PTTI) — Canonsburg, Pennsylvania
Overview:
PTTI designs and manufactures large power transformers for long-term grid performance and industrial reliability.
Key Products:
- Power transformers up to 500 kV
- Network and regulating transformers
- Field testing and diagnostic services
Certifications: ISO 9001, ISO 14001
Notable Strengths:
PTTI’s extensive test facilities and material traceability systems ensure performance under high thermal and mechanical stresses.
8. Virginia Transformer Corporation (VTC) — Roanoke, Virginia
Overview:
VTC is the largest privately owned U.S. transformer producer, serving industries, renewables, and public utilities.
Key Products:
- Power and auto transformers up to 300 MVA
- Specialty transformers for mining and rail
- Industrial-grade step-up systems
Certifications: ISO 9001, ISO 14001
Notable Strengths:
Known for its custom designs and short production cycles, VTC is a leader in specialized, high-performance transformer builds.
9. Delta Star, Inc. — Lynchburg, Virginia
Overview:
Delta Star is a pioneer in mobile substations and portable power solutions, serving utilities and disaster recovery projects.
Key Products:
- Mobile and skid-mounted power transformers
- Compact substations up to 230 kV
- Emergency grid support systems
Certifications: ISO 9001, ISO 14001
Notable Strengths:
Delta Star’s mobile and modular designs ensure rapid deployment and operational continuity during grid outages.
10. Hyundai Power Transformers USA — Montgomery, Alabama
Overview:
Hyundai Power Transformers (HPT) delivers large-scale transformers built at its advanced 300,000 sq. ft. U.S. facility.
Key Products:
- Power transformers up to 800 kV
- Smart monitoring and cooling systems
- Transmission-grade transformer units
Certifications: ISO 9001, ISO 14001
Notable Strengths:
HPT’s American manufacturing base and rigorous testing make it a top supplier for utilities requiring DOE-compliant, high-voltage equipment.
Zetwerk: A Global Partner for the U.S. Power Industry
Zetwerk complements the U.S. transformer ecosystem with global manufacturing scale, ISO-certified precision, and export reliability. Its transformers are custom-engineered for North American grid codes and efficiency standards, ensuring interoperability and dependable field performance.
Key Capabilities:
- Fully type-tested designs under IEC 60076 and DOE 2016
- Digital factory systems ensuring traceable production
- Rapid global logistics for OEMs and EPCs
- Manufacturing synergy with U.S. grid requirements
By combining U.S. engineering collaboration with Indian manufacturing scale, Zetwerk enhances supply chain resilience and supports faster project execution across the Americas.
Conclusion
The U.S. power transformer market is defined by engineering excellence, reliability, and certified production systems. The top 10 manufacturers—GE, ABB Hitachi, Siemens Energy, SPX, Zetwerk, Howard Industries, PTTI, VTC, Delta Star, and Hyundai Power Transformers—represent the core of North America’s power infrastructure.
While established American manufacturers dominate domestic production, Zetwerk’s ISO-certified and export-oriented approach strengthens cross-border collaboration, ensuring on-time, cost-efficient, and compliant power transformer solutions for global energy networks.
FAQs
a. GE, ABB Hitachi Energy, Siemens Energy, SPX, Zetwerk, Howard Industries, and others lead the market.
a. Most comply with IEEE, DOE 2016, IEC 60076, and ISO 9001/14001 certifications.
a. Zetwerk supplies ISO-certified, DOE-compliant power transformers and components to U.S. utilities and OEMs.
a. Yes, many U.S. manufacturers export to Latin America, Europe, and Asia-Pacific regions.
a. Zetwerk combines ISO-certified global manufacturing with digital quality control and shorter lead times for North American clients.
