Unit Auxiliary Transformer Swap-Out
Barnhart was contracted by a power company to swap out a Unit Auxiliary
Transformer. The new UAT was staged on stands and beams, then they
jacked and slid out the old UAT using the Barnhart light slide system, and
transported the new UAT to site and jacked and slid it into place.
There were several engineering challenges to overcome during the course
of this project. First was the location of the existing UAT. It was located
under 500Kv lines, next to a 22Kv switch gear, and surrounded by river
rock. Secondly, the 22Kv switch gear was live during the pre-outage
portion of our work as it supported their alternate Start-up Generator,
also located next to the UAT. Finally, the whole area was protected
by concrete curbs used to catch a potential oil leak which we were not allowed to remove.
Transportation was via 6 lines of THP Goldhofer trailer. The light slide
system performed very well and without issue. The Little Rock branch
provided crane support with their 300 ton crane. They also provided
several of the crew members.
The outage was delayed several shifts of removal time as the power company worked through some off site power concerns. When finally given the green
light we were able to make up about 42 hours of the outage time. This
was due mainly to great coordination between Barnhart, Entergy, and
their transformer subcontractor. This was an example of finding ways to
continue working other related scopes of the project as well as refining our preparation for the eventual jack and slide ops.