Siemens, Con Edison install resilience power transformer

Siemens and Con Edison of New York, Inc. have successfully installed a plug and play mobile resilience power transformer in record time.

While it usually takes several weeks to transport and install a new power transformer on-site, the team completed transformer positioning and final installation in only 30 hours.

ConEd is keeping the location of the transformer confidential for security purposes, but it is meant to help power the NYC region.

“Grid resilience is a matter that is very important for us as well as our customers — and in the end, also for society,” said Dr. Beatrix Natter, CEO of Siemens Transformers. “The fast-track installation time of our innovative plug and play mobile resilience transformers is proof that our grid resilience concept is a real first aid kit for emergency situations.”

Siemens mobile resilience transformers were developed together with Con Edison as a part of the Siemens Pretact concept for maximum grid resiliency. Siemens delivered the mobile resilience transformers late last year that will act as an emergency measure in case of unplanned outages — like those caused by hurricanes — or for planned outages.

The transformers were designed as single-phase units to be as compact and lightweight as possible. For ease and quick installation, they are transported fluid filled (transport weight of 216,000 lbs includes fluid) and equipped with plug and play bushings and cable connections.

The insulation fluid is ester, a synthetic fluid derived from natural oils, instead of mineral oil, reducing the fire and explosion risk as well as mitigating possible environmental threats. Additionally, ester allows for operation at higher temperatures, which reduces the unit’s size and weight. To be able to quickly connect the transformers to different substations, they are designed in a versatile way and have connections for several voltage levels (345 kV, 138 kV or 69 kV) and the secondary connection may be made via bushing to an overhead bus or via a plug in cable connection.

The assembly and installation of the units was performed by three teams who were supported by representatives from Siemens, Pfisterer & MR Reinhausen. The teams disconnected the existing transformer from the station overhead bus and installed transformer bushings and surge arresters, set up the pothead stands and secondary cable connections, mounted and connected the common control cabinet and set up the control cable connections between the transformers and the relay house.

For easy storage and fast deployment all accessories are containerized and allow for maximum flexibility of setup depending on the specific location where the transformers are needed. For example, the 138 kV connections to the bus were at a distance of 150-220 feet from the units, but the easy to install cables and pothead stands nevertheless allowed for a connection within just a few hours. Distances up to 400 feet can be managed because of cable extension sockets that are provided with the units. Even the common control cabinet can be placed over 150 feet away from the units and still be connected with all three transformers within less than two hours. After installation, the commissioning team tested the transformers and connections to the relay building, which marked the final step of the fastest 300 MVA EHV transformer installation in history.

The Pretact concept of Siemens Transformers combines several modules that assist transformer operators in preventing transformer failures by dedicated service measures, protecting transformers from harm likeby natural disasters, and the innovative mobile resilience transformers that offer a backup for unplanned outages, just in case all other precautions fail, and support the coverage during planned outages as well.

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The Clarion Energy Content Team is made up of editors from various publications, including POWERGRID International, Power Engineering, Renewable Energy World, Hydro Review, Smart Energy International, and Power Engineering International. Contact the content lead for this publication at

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