Griffin Wheel - Transformer Replacements

Keokuk, IA

Klingner provided environmental, structural, electrical and mechanical design services to develop the sequence of lifting and coordinating with the overhead crane manufacturer for engineered lifts to replace three 132,000 lb transformers, using the existing 50-ton bridge cranes, inside the Griffin Wheel Company Keokuk plant.

Due to a very small clearance on each side of the new transformer, Klingner designed a set of four custom-length choker cables to account for the eccentric center of gravity of the transformer. The chokers were critical in design and ensured that the crane hook was directly above the center of gravity and that the transformer hung plumb, which allowed the 17.5’ tall transformer to fit through the narrow, existing opening.

Klingner engineers designed new 34K volt switchgear to power the new transformers. Detailed conduit routing design was provided, while developing methods to reuse existing underfloor conduits while minimizing downtime. Engineers designed a new vacuum interrupter for installation within an existing transformer vault to control power to the new transformers. A new 72-piece buss bar adapter to connect new transformers to existing delta closure was designed. This also maintained the ability to re-install the existing adapter and transformer as a backup system. To enhance employee safety, a new Kirk-key interlock system was designed for control of power and personnel protection.

Structural services included design modifications to the existing concrete transformer vault walls and ceilings, and the design of removable precast roof and wall panels. The roof and wall panels were selected to reduce the amount of maintenance that was required on the CMU walls that were replaced. These modifications allowed access for the overhead crane hook to set the transformers in place quickly, while minimizing the plant shut down time.

Klingner included designs for new service platforms, equipment supports and modifications to strengthen the transformer base foundations and vault ceiling, including special lifting sequence in order to utilize Griffin Wheel Company’s internal overhead cranes to remove and replace the transformers.