Summary
The paper presents the development and deployment of a new generation of resiliency transformers, focusing on a highly versatile 58/65/93 MVA reconfigurable area station transformer (AST) engineered for rapid response and enhanced grid resilience in urban environments such as New York City. The transformer utilizes an advanced insulation system based on aramid paper and aramid pressboard, combined with synthetic ester liquid, which materials provide superior thermal stability, dielectric strength, and fire safety. This insulation system enables safe operation at higher temperatures and supports demanding overload requirements, with the transformer capable of operating at hot spot temperatures up to 220°C.
Read more Read lessThe motivation for these advancements stems from the need to mitigate outages caused by severe weather events, equipment failures and the need to supply electricity to customers, as highlighted by the impact of Superstorm Sandy in 2012. Con Edison, serving over nine million people, required transformers that could be quickly deployed, easily transported, and installed in constrained urban spaces while maintaining high reliability and overload capability.
The AST Type 2 transformer supports multi-voltage and multi-impedance operation
(58, 65 and 93 MVA ratings; 132 - 65 kV HV and 13.8 - 28 - 35 kV LV), managed by four deenergized tap changers and one on-load tap changer for precise voltage regulation. The compact design, plug-and-play features (dry-type plug-in bushings, direct cable connections, low-profile conservator, quick-connect cooling), and reduced weight facilitate rapid installation and transport.
Extensive testing validated the mechanical and thermal performance of aramid insulation, including bending, friction, and dielectric strength tests, demonstrating superior flexibility
(where needed), bonding, and reliability under stress. The transformer underwent rigorous multi-phase testing, including dielectric, insulation, ratio, impedance, temperature rise, and functional checks. All five operating configurations were heat-run tested, with fiber optic probes monitoring winding temperatures. Special attention was given to the impact of ester liquids on diagnostic tests, such as dissolved gas analysis (DGA) and core insulation resistance, which differ from mineral oil-filled units but remain within acceptable limits.
The project exemplifies strategic partnership among the utility, the transformer manufacturer, and the aramid insulation material supplier, enabling innovation and customization. This collaboration resulted in transformers with >10% higher rating than previous types, rapid deployment capability, and improved resilience and operational flexibility.
In summary, innovative designs using aramid insulation and ester liquids have significantly advanced transformer resilience, validated through pilot installations and full-scale projects.
These solutions are essential for modern, robust, and flexible energy infrastructure, especially in complex urban grids.
Additional informations
| Publication type | Session Materials |
|---|---|
| Reference | A2_11422_2026 |
| Publication year | |
| Publisher | CIGRE |
| Country | Poland |
| Study committees | |
| File size | 1 MB |
| Price for non member | 30 € |
| Price for member | 30 € |
Authors
SZEWCZYK Radoslaw - DuPont, Poland; DUART Jean-Claude - DuPont, Switzerland; O’MALLEY Anastasia - Consolidated Edison Co. of NY, USA; WIND Rene - Siemens Energy, Austria; SCHWEIGER Ewald - Siemens Energy, Germany
Keywords
