Midwest Energy Installs First Skid-mounted Substation in Atwood

On Tuesday, May 26, Midwest Energy took delivery of its first skid-mounted substation.  The new sub sits adjacent the existing Atwood Substation.  

The skid-mounted substation, which will soon replace the much larger and decades-old Atwood Sub, differs from traditional substation designs that are somewhat customized to each site, and includes the design of a steel structure and supporting foundations.  Transformers, switches, conductors, insulators and other devices are then brought in and assembled on site, requiring several weeks of work.  With the skid-mounted substation it is shipped fully assembled on a single steel frame, ready to set on the foundation and connect to existing power lines.  The on-site construction time is significantly reduced.

While the overall cost of the skid-mount substation is slightly higher, it is a better fit for the small amount of space available for a new installation without having to partially deconstruct the existing substation to make room for the new equipment.

Skid-mount substations aren't ideal for each setting, but according to Bill Dowling, VP for Engineering and Energy Supply, "In this project it made the most sense to try to install a new substation very near the existing substation.  However, there is only so much ground available at that site.  To build a conventional substation at the same site, without taking extensive measures to ensure continuity of service to the residents of Atwood during the construction phase, presented a significant and expensive challenge."

With the compact design of the skid-mounted substation crews built a new foundation and connecting lines in advance.  With the new substation lifted into place using a large crane from Hess Services of Hays, crews will spend this week finishing underground work.  Once testing is complete, electric load will be shifted from the old substation to the new, and the old substation will be dismantled.

Bob Hoffman, Substation Manager at Hays, said any set of "firsts" is always hard.  "Chris Hund (Engineer II at Hays) has been the spearhead on this project, but we had a really good team effort from all of engineering to get this here," Bob said.   

Bill noted that since this is the first skid-mounted substation to be installed by Midwest Energy, "We will evaluate its effectiveness when installation is completed to determine whether we will utilize this type of equipment on future projects.  There are other places where we believe this might be a good alternative, but no final decisions will be made until we place this first unit in service."

Dowling added he expects this skid-mounted substation to have a service life of at least forty years.