Physical Design

The physical design for a typical substation project requires an investigation of field conditions, application of design standards to the site-specific conditions, and continued engineering analysis and guidance.

During the investigation of field conditions, S&C gathers geotechnical information and data such as legal and topographical surveys and soil samples.

In developing of the physical design, S&C applies the customer’s available design and CAD standards as well as the appropriate national standards. Basic electrical clearances and spacing are determined according to NESC, ANSI, and NEMA standards. These criteria are used to develop new or modified foundation drawings, grounding plans, and structural details, as well as a bill of materials for the design. Additional landscaping and architectural treatment can be provided if requested.

Development of the physical design is continually supported by engineering analysis and guidance. Proposed conductors are reviewed to ensure that they are adequately sized, and calculations are performed to select the size of the station service transformer. Calculations to analyze the substation ground grid are performed in accordance with IEEE Standard 80. Mechanical loading criteria are developed to account for wind and ice loading, forces due to short-circuit currents, and seismic loads. A structural analysis is then prepared utilizing this loading data. In addition, an evaluation of the site requirements and applicable regulations are used to develop an oil-spill prevention, control, and countermeasure plan.

The final result is a design package that clearly and accurately defines the required construction work.