34.5kV Underbuild Upgrade

To address growing reliability concerns in the Florida Keys, Welty Energy, in collaboration with a distribution contractor, assisted a local utility by engineering seven miles of 34.5kV line to be underbuilt on an existing 138kV transmission line facility.

Goals:

• Analyze seven miles of existing 138kV transmission facilities and engineer a new underbuilt 34.5kV line.
• Provide stamped construction deliverables including P&P drawings, structural loading reports, wire stringing charts, and staking tables for new 34.5kV skip-span structures

Process:

• To begin, Welty Energy gathered available data from the local utility, steel pole manufacturers, and insulator/hardware manufacturers to accurately model the existing 138kV Line and Method 4 structures in PLS-CADD. A site visit was held with the distribution contractor and the utility to discuss design possibilities for the underbuilt 34.5kV line.
• Welty Energy engineered the proposed 34.5kV underbuilt line design in PLS-CADD and analyzed structural capacities and appropriate facility clearances.
• After final engineering, Welty Energy provided stamped copies of plan and profile drawings, stringing charts, skip-span structure staking charts, and equipment utilization reports.

Conclusion:

• Welty Energy utilized LiDAR survey in conjunction with manufacturer drawings, available plan and profile drawings, PLS-CADD, and AutoCAD to engineer the 34.5kV line’s attachment to the existing 138kV line.
• Welty Energy ensured the utility’s compliance with NESC 2023’s design criteria.
• Welty Energy collaborated with all parties to complete the project in an efficient manner.

Process Alternative: