Substation Power Transformers
This contract provides up to five 138kV–24.9/13.2kV three-phase substation power transformers rated 25/33/50/56 MVA. Suppliers deliver oil-immersed delta-grounded wye units with load tap changers, dual secondary voltage switching, factory and field testing, design review support, and full assembly services.
Description
This contract establishes a source for up to five oil-immersed, three-phase 138kV–24.9/13.2kV substation power transformers. It connects entities with experienced manufacturers that provide fully engineered, factory-tested transformers with load tap changers, dual secondary voltage capability, and complete field assembly services.
Key Service Categories:
- Transformer Design And Manufacturing: 25/33/50/56 MVA delta-grounded wye units with copper windings and 7% impedance
- Load Tap Changer Systems: ±10% regulation with 32-step OLTC located on the secondary winding
- Dual Secondary Voltage Switching: External selector switchable between 24.9kV and 13.2kV with full 56 MVA capability
- High Lightning And BIL Performance: 650kV BIL on 138kV windings and enhanced impulse ratings for regional lightning exposure
- Factory Testing And Loss Verification: ANSI C57.12.90 compliant testing including loss, impulse, noise, and performance verification
- Field Assembly And Vacuum Oil Filling: On-site offloading, assembly, oil processing, and final energization support
Benefits Aligned With Desired Outcomes:
- Improved System Reliability: Designed for infinite bus short-circuit withstand and high through-fault conditions
- Voltage Regulation Flexibility: On-load tap changer and dual secondary voltage support changing distribution needs
- Long-Term Asset Performance: 60-month warranty with factory drying, vapor phase processing, and moisture control
- Standards Compliance: Manufactured to ANSI, IEEE, NEMA, and IEC requirements with documented testing
These services support resilient substation expansion with fully engineered transformers designed for high reliability, lightning performance, and long-term operational stability.

