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Public utilities

Typical Structures for Transmission Lines in Des Moines, Iowa

Strategic Insights

— 1 min read

Des Moines' transmission lines, owned and operated by Corn Belt Power Cooperative, exhibit distinct structural characteristics. The Typical Wood Pole, for instance, has a height of around 56.5 feet after installation, but since it's not noted in the document, this remains undetermined. Steel structures, such as steel poles or towers, are made of ductile iron, with the H-Frame structure bracing type and spacing between H-Frame poles left unspecified. Meanwhile, support arm details, such as type and material, are absent.

The transmission line, known as Weaver DC, operates at a nominal voltage of 69 kVAC and has a maximum capable voltage of 72.5 kVAC. The vertical overhead clearance requirement for phase conductors is determined by the Iowa Electrical Safety Code and the National Electric Safety Code (NESC). The calculated clearance for open ground is 19.2 feet, while it is the same for roads. No clearance requirement is specified for railroad crossings or water. The transmission line's phase conductors are typically ACSR, with a code word "Hen (Oval)" and a size of 477 kcmil.

Key Takeaways:

  • The Typical Wood Pole has a lack of documentation regarding its characteristics, including height, species, treatment, class, and length.
  • Steel structures, such as steel poles or towers, are made of ductile iron but lack details regarding H-Frame structure bracing type and spacing between H-Frame poles.
  • Support arm details, including type and material, are absent.
  • The Weaver DC transmission line operates at a nominal voltage of 69 kVAC and has a maximum capable voltage of 72.5 kVAC.
  • The vertical overhead clearance requirement for phase conductors is determined by the Iowa Electrical Safety Code and the NESC.
  • Calculated clearances for open ground and roadways are 19.2 feet, while clearances for railroad crossings and water are not specified.
  • The transmission line's phase conductors are typically ACSR with a code word "Hen (Oval)" and a size of 477 kcmil.

Statistics:

  • Maximum capable operating voltage: 72.5 kVAC
  • Nominal operating voltage: 69 kVAC
  • Calculated clearance for open ground: 19.2 feet
  • Calculated clearance for roadways: 19.2 feet
  • Calculated clearance for railroad crossings: not specified
  • Calculated clearance for water: not specified
  • Size of phase conductors: 477 kcmil
  • Material of phase conductors: ACSR
  • Code word of phase conductors: Hen (Oval)

Sources:

  • Iowa Public Utilities Commission document, Rev. 6/2020
  • Corn Belt Power Cooperative, Weaver DC transmission line
  • Iowa Utilities Board, E-21440
  • Iowa Electrical Safety Code
  • National Electric Safety Code (NESC)

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