Pennsylvania Transformer Technology, LLC

345kV High Voltage Power Transformer — 90 / 120 / 150 MVA

HV Power Transformer 40 MVA, 3-Phase
Reliable Power, Proven Performance

The 345kV Power Transformer from Pennsylvania Transformer Technology delivers up to 150 MVA of reliable, high-efficiency performance for transmission and substation applications.

Designed to stringent ANSI and IEEE standards, the 345kV Power Transformer features rugged copper construction, advanced cooling and insulation systems, and is backed by comprehensive service and warranty support.

The 345kV Power Transformer by Pennsylvania Transformer Technology, LLC (PTT) is engineered for high-capacity substation and transmission applications requiring exceptional reliability, mechanical strength, and efficiency. Designed, assembled, and tested in the Canonsburg, Pennsylvania facility, this three-phase, liquid-immersed unit provides 90/120/150 MVA ONAN/ONAF/ONAF ratings with copper windings, core form design, and dual-stage forced-oil-air cooling for optimum thermal performance.  

Key Specifications ​​ 345kV High Voltage Power Transformer

​MVA Ratings

Power Rating

  • 90 / 120 / 150 MVA (ONAN / ONAF / ONAF)
Cooling System Options

Cooling System Method

  • ONAN / ONAF / ONAF — Oil Natural Air Natural for base rating and Oil Natural Air Forced for higher ratings.
Voltage Rating

Voltage Ratings

  • Primary (High Voltage): 345 kVY / 199.186kV
  • Secondary (Low Voltage): 34.5 kVY / 19.919kV
  • Tertiary (Delta): 13.8kV Δ (buried tertiary winding)
Impedance

Total Weight

  • 543,350 lbs (core + coil 230,950 lbs; tank 117,100 lbs; oil 195,300 lbs)
345kV Power Transformer ​Performance Highlights
  • Precision-engineered for utility-scale transmission and substation applications
  • High efficiency: exceeding 99.6 % at all loading levels
  • Low sound and low loss operation for minimal environmental impact
  • ANSI C57.12.90-compliant short-circuit design, with impedance variation ≤ 2 % after test
  • Heavy-duty mechanical construction for high fault-withstand capability
  • Dual-stage cooling ensures stable temperature control under continuous overload
345kV Transformer ​Applications
  • High-voltage substations and utility transmission networks
  • Power generation interconnect transformers (renewable or conventional)
  • Large industrial complexes and regional grid interties
  • Projects requiring high efficiency and voltage stability at 345kV class
Testing and Quality Assurance
  • No-load and load losses
  • Applied and induced voltage tests
  • Temperature rise tests
  • Efficiency and impedance verification
  • Routine oil and insulation diagnostics
345kV Power Transformer ​ Design and Construction Features
  • High-Capacity Performance:
    90 / 120 / 150 MVA ONAN/ONAF/ONAF transformer with copper windings, circular core design, and efficiencies exceeding 99.6 % for reliable utility and transmission service.
  • Rugged, Proven Construction:
    Heavy-duty steel tank with conservator-type oil system, dual-stage forced-air cooling, and ANSI 70 Gray finish—engineered to meet ANSI C57 and IEEE C57.12 standards for mechanical strength and fault withstand.
  • Advanced Electrical Design:
    345kVY / 34.5kVY / 13.8kV Δ configuration with 11.5 % impedance, 1175kV BIL insulation, and fully factory-tested per ISO 9001:2015 quality protocols.
  • Comprehensive Support & Warranty:
    Backed by a standard 12 / 18-month warranty or optional 5-year limited coverage, with field service and testing available from PTTI’s certified engineering team.
Certifications and Compliance
  • ISO 9001:2015 with Design – Certified by Smithers Quality Assessments for the design, manufacture, and testing of power transformers 10–> 60 MVA and above.

345 kV Power Transformer: Frequently Asked Questions

Explore the featured Pennsylvania Transformer Technology project’s ratings, cooling, applications and testing.

What is the capacity of PTT's featured 345 kV transformer?

PTT's featured three-phase 345 kV transformer is rated 90/120/150 MVA, corresponding to its ONAN/ONAF/ONAF cooling stages.

What are this 345 kV transformer's voltage ratings?

The featured transformer has a 345 kV high-voltage winding, a 34.5 kV low-voltage winding and a buried 13.8 kV delta tertiary.

How does ONAN/ONAF/ONAF transformer cooling work?

ONAN uses natural oil circulation and natural airflow. ONAF adds fan-forced airflow, enabling this transformer’s higher 120 MVA and 150 MVA ratings.

What applications suit PTT's featured 345 kV transformer?

Applications include utility substations, transmission networks, generation interconnections, large industrial facilities and regional grid interties.

What tests does PTT perform on this transformer?

Testing covers no-load and load losses, applied and induced voltage, temperature rise, impedance, efficiency, and oil and insulation diagnostics.

Where does PTT build this 345 kV transformer?

PTT designs, builds and tests this transformer at its Canonsburg, Pennsylvania, facility under ISO 9001:2015 quality processes.

Discuss your transformer specifications with PTT. Request project information or call (724) 873-2100.

Ask How PTT Can Deliver on Your Power Transformer Specifications