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Midel 7131 synthetic ester transformer oil

PROJECT: Mobile Transformers | New York, USA

ESTER TYPE: MIDEL 7131 synthetic ester

PURPOSE: Increase grid resiliency with emergency power solutions

[ OVERVIEW ]

In 2012, Hurricane Sandy hit the eastern seaboard of the USA. A well-known New York utility company, providing electric, gas and steam services to 10 million customers in the five boroughs of New York City and Westchester County, experienced significant service disruption.

As a result, the utility made a commitment to improving grid resiliency against future extreme weather events.

The utility partnered with transformer manufacturer Siemens Energy to develop mobile resiliency transformers. These would allow the utility to quickly deploy and replace a failed transformer and restore power when needed. One critical element in the development of these innovative assets was MIDEL synthetic ester transformer fluid.

[ SITUATION ]

The mobile resiliency units were designed to be dual rated so they could be used in any of the utility’s substations. They could operate either as a 300 MVA transformer with the 345 KV primary or a 150 MVA transformer with the 138 KV primary. The transformers have a high overload capability and can provide 170% of the nameplate rating during the demanding summer months. The units retain the same operating regulation ability with a low tap changer that can regulate either plus or minus 12% for the 300 MVA operation or 8% for the 150 MVA operation.

Flexibility is a key design feature – the units can be deployed at different locations, and so the bushings that interconnect with the substation’s existing bus connection could be either done through an open-air bus connection or with a secondary cable plug connection, providing flexibility in placement of these transformers. They were designed to be three single phase units to simplify transportation and make them more lightweight so they can be transported pre-filled with MIDEL synthetic ester insulating fluid.

After Hurricane Sandy, this New York utility updated its design criteria for its facilities; they now design to a FEMA 100-year flood plain, plus an additional three feet to account for any flooding within containment areas. New concrete moats were installed around critical equipment. Watertight doors and floodgates were constructed, which could be used to secure the area in the case of an incoming storm, assisted by new high velocity, high-capacity flood pumps. For its power transformers the control cabinets and CT cabinets were elevated above the flood level.

[ RESULT ]

The use of MIDEL 7131 synthetic ester fluid for the mobile resiliency units was a carefully deliberated decision based on detailed research and consultation with the MIDEL technical team. The fluid gave the highest assurance of fire safety and biodegradability – in contrast with the potential flammability of mineral oil. Using this fluid also enabled the transformers to be shipped pre-filled with insulating fluid, shortening installation time; the fluid’s use also supports the utility’s drive for sustainability.

“To simplify transportation, a hybrid high temperature installation system was used that allows a reduction in shipping size and weight. The use of synthetic ester liquid, which is readily biodegradable, allows us to ship the transformer liquid filled, so there’s no fluid processing required on site – further shortening installation time.” – Project Manager, Utility Substation Equipment

As a result of this positive experience with MIDEL 7131, the fluid has been exclusively adopted by the utility for all its new substations.

The use of MIDEL ester fluids in these sectors supports the following UN Sustainable Development Goals:

Related Downloads

MIDEL 7131 Mobile Transformers NY