Line Rating & Up-Rate Using PhaseRaiser® Technology

Line Rating & Up-Rate Using PhaseRaiser® Technology

138kV – Increasing Vertical Clearances by Raising (64) H-Frame Structures

Commissioned by a major Midwest Transco, Realtime Utility Engineers completed a load rating study of an existing 138kV transmission line.  The study revealed that the (36) mile line had inadequate conductor-to-ground clearances for the desired loading.

PhaseRaiser® Technology was chosen to increase cross arm to ground heights and vertical clearances. Working with PhaseRaiser® supplier Laminated Wood Systems, Realtime applied the lifting hardware to (64) H-frames, raising the structures (5) to (15) feet.

Project Scope:
Realtime provided a full range of services for the project, from surveying to project close-out, including:

  • Managed the acquisition of LiDAR survey data, as well as low flight digital video and stills, using helicopter-mounted equipment.
  • Processed the survey data and created a digital line model using Power Line Systems’ PLS-CADD software.
  • Prepared a load rating report, documenting NESC code status at various conductor temperatures and related MVA loads.
  • Identified H-frame structures requiring modification to accommodate required line loading.
  • Assisted in evaluating the application of PhaseRaiser® versus other construction options.
  • Identified the specific remediation to be applied at each structure.
  • Provided construction documents for material procurement and construction.
  • Provided engineering support during construction.
  • Completed as-built drawings and record documentation.

Design Challenges & Solutions:
Traditionally, achieving the desired line rating would have required reconstructing the line by replacing structures. Working with our client, Realtime justified the use of PhaseRaiser® technology to shorten the construction schedule and reduce project cost by (50) percent. As an added bonus, the work was able to be competed with the line in service.