First bullet resistant retrofit ordered for a transformer

Siemens, the pioneer in resilience solutions for transformers, has received an order for the world’s first bullet resistant retrofit solution for a power transformer. The two, three-phase transformer units have been in service since 2013 and 2014, and as with all power transformers, play a strategic role in the US power grid. The bullet resistant solution is part of Siemens’ resilience concept, Pretact®, which is made up of three pillars to “prevent”, “protect” and “react”. The bullet resistant design protects these valuable assets from harm, elevating transformer availability and safety to the next level.

Siemens Transformer Lifecycle Management (TLMTM) will design the retrofit solution and install shielding to protect the tank and conservator from all sides. The protection system panels have been designed and tested to withstand rifle projectiles according to VPAM Class 13. This is the highest class of rifle projectiles specified by VPAM, and is the most powerful commonly available bullet that is not considered a destructive device under the United States National Firearms Act.


A big advantage of this Siemens bullet resistant system is that it does not require an additional foundation, and panels are mounted directly on the tank. The transformers’ current oil-filled bushings will also be exchanged and replaced with HSP Resin Impregnated Synthetic (RIS) bushings. This means that even if an RIS bushing is penetrated by a bullet, it will not lead to fire because the polymer insulated bushings do not contain oil.


“This great success for Siemens Transformer Lifecycle Management demonstrates our innovation lead with superior solutions for transformer resilience and is the evidence that our Pretact® resilience concept is exactly what utilities currently need. In the end, it is not only about preventing transformers from operational failures, but also about protecting them against harm from the outside”, says Leone Lattanzio, Head of Customer Service for Transformers within the Energy Management division (EM TS CS TR).