Pennsylvania Transformer Technology, LLC

Delivered to Florida

69kV, 44.8 MVA unit (69 D - 13.8Y kV)

69kV High Voltage Power Transformer  40 MVA, ​13.8 kV, 60 Hz

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

Delivering up to 40 MVA of dependable power, the ST-905 Transformer combines precision engineering, advanced cooling, and copper-wound durability to keep the substation running efficiently and reliably for decades.

The ST-905 Substation Power Transformer by Pennsylvania Transformer Technology, LLC (PTT) is a high-performance, three-phase unit delivering up to 40 MVA at 69/13.8 kV for reliable and efficient power distribution. Expertly engineered to ANSI, IEEE, NEMA, and ASTM standards, this transformer features advanced ONAN/ONAF/OFAF cooling, copper windings, and a precision load tap changer for stable voltage regulation. Complete with bushings, oil, surge arresters, and accessory equipment, the ST-905 is built for long-lasting performance, superior thermal efficiency, and dependable operation in utility and substation environments. Let PTT engineer a custom solution to meet your needs.

Key Specifications Power Transformer 69kV 40 MVA

​MVA Ratings

MVA Ratings

  • Self-cooled (ONAN): 24 MVA @ 55/65°C rise (by resistance)
  • 1st stage cooling (ONAF): 36 MVA @ 55/65°C rise
  • 2nd stage cooling (OFAF): 40 MVA @ 55/65°C rise
Cooling System Options

Cooling System Options

  • Fans: ONAN / ONAF
  • Extended Fans: ONAF / ONAF / ONAF
  • Fans and Oil Pump: ONAN / ONAF / OFAF
Voltage Rating

Voltage Rating

  • 69 / 13.8 kV, 60 Hz
Impedance

Impedance

  • HV to LV: 7–8%
  • Base: 24 MVA
  • Must be within applicable ANSI limits at lowest temperature rise
69kV, 40 MVA Power Transformer Key Features
  • High capacity design: Rated for up to 40 MVA, 69/13.8 kV, three-phase operation.
  • Advanced cooling system: Dual-stage ONAN/ONAF/OFAF configuration with automatic temperature control.
  • Copper windings: Ensures optimal conductivity, efficiency, and longevity under heavy load.
  • Load Tap Changer (LTC): Reinhausen RMV-II mechanism providing ±10% voltage adjustment in 32 steps.
  • Precision voltage regulation: Automatic control with Beckwith Model M-2001C system for smooth load balancing.
  • Durable tank design: Welded steel plate construction with bolted radiators, corrosion protection, and OSHA-approved fall safety system.
  • Comprehensive protection: Surge arresters, bushing current transformers, pressure relief devices, and sudden pressure relays.
  • Oil preservation system: Automatic nitrogen system with pressure regulation and alarm contacts for reliability.
  • Compliant engineering: Built to ANSI, IEEE, ASTM, and NEMA standards for performance and safety.
  • Thorough testing and inspection: Includes factory and field acceptance testing per ANSI C57.12 standards.
69kV, 40 MVA Power Transformer Key Benefits
  • Superior reliability: Engineered to deliver continuous, stable power with minimal downtime in demanding substation environments.
  • Extended equipment lifespan: Efficient cooling and robust copper windings reduce thermal stress and extend operational life.
  • Improved voltage stability: Automatic load tap changing maintains consistent voltage under fluctuating load conditions.
  • Enhanced operational safety: Equipped with advanced alarms, relays, and safety controls to protect personnel and equipment.
  • Ease of maintenance: Accessible design with removable components, diagnostic indicators, and comprehensive monitoring systems.
  • Lower lifecycle costs: Optimized design minimizes losses, boosting efficiency and reducing total operating expenses.
  • Regulatory assurance: Fully compliant with major U.S. electrical standards, ensuring code alignment and utility compatibility.
  • Proven performance: Built by experienced engineers to meet exacting customer specifications with guaranteed quality testing.
Ask How PTT Can Deliver on Your Power Transformer Specifications