Confidential Client
Southwest USA
Energy
Overview
A major electric generation company operates critical power generation assets that help deliver reliable electricity to homes, businesses, and industrial facilities throughout the region. As demand for dependable power infrastructure continues to grow, maintaining the reliability and performance of high-voltage transmission and switchyard equipment remains essential to ensuring grid stability and long-term operational resilience.
To support these objectives, the company initiated a project at its energy center to replace nine existing 345kV breakers within the facility's switchyard. The project was designed to increase breaker interrupting ratings and enhance the overall reliability of the high-voltage electrical system. Nexus Engineering Group was selected to provide detailed engineering and design services supporting the removal of the existing breakers and installation of nine new replacement units.
Nexus' scope included development and updating of critical electrical design documentation, including single-line diagrams, three-line diagrams, control schematics, wiring diagrams, switchyard plans and elevations, cable schedules, bills of material, construction scope documentation, project scheduling, and overall project coordination. The project also incorporated detailed field verification activities and advanced 3D scanning to support design accuracy and successful implementation.
Challenge
While the project appeared straightforward on the surface, several unique technical and schedule-driven challenges had to be addressed to ensure success.
Designing from Preliminary Drawings
One of the most significant challenges involved an aggressive project schedule that required engineering to proceed before final vendor drawing packages were available. To maintain the client's outage schedule, Nexus utilized preliminary drawings and representative equipment information to begin design activities while final manufacturer documentation was still in development. This approach introduced additional engineering risk because final equipment dimensions, configurations, and interfaces had not yet been confirmed.
Existing Site Conditions and Space Constraints
The replacement breakers needed to be installed within an existing operating 345kV breaker yard while utilizing existing infrastructure wherever possible. Existing drawings did not fully reflect current field conditions, creating the potential for equipment interferences, constructability concerns, and schedule impacts during installation. In addition, the new breakers had to integrate with existing structures, high-voltage lead configurations, control systems, and cabling networks while maintaining operational continuity.
Reuse of Existing Cable and Control Systems
The project required interfacing with existing cable systems and control infrastructure while preserving existing operational functionality. Existing cabling was targeted for reuse whenever possible, requiring detailed field verification of wiring, termination points, and control panel configurations. Additional complexity was introduced because the replacement breakers required both AC and DC power sources, necessitating new design considerations and modifications to existing electrical systems.
Expanded Design Requirements
As engineering progressed, the project evolved beyond the original scope. The final design package required significantly more drawings than originally anticipated, and existing CAD files were unavailable for many legacy documents, requiring numerous drawings to be recreated. The team also encountered previously undocumented breaker contacts and external references that required extensive investigation to support future commissioning and testing activities.
Solution
Nexus responded to these challenges through a proactive engineering approach that combined advanced field data collection, detailed verification efforts, and close client collaboration.
A key differentiator was the decision to perform a comprehensive 3D scanning and laser survey of the existing 345kV switchyard. Although not originally included within the project scope, the scan provided highly accurate field data that allowed the team to develop a detailed three-dimensional model of the yard and verify equipment locations, clearances, and structural relationships. During this effort, Nexus identified that the replacement breakers would require a 180-degree orientation change to avoid conflicts with existing infrastructure. Discovering and resolving this issue during design eliminated the risk of costly field rework and potential outage delays during construction.
The Nexus team also conducted extensive field reviews of existing wiring systems, control panels, cable terminations, and switchyard conditions to validate legacy documentation and ensure design accuracy. By combining these field investigations with the data gathered through 3D scanning, the team successfully developed a reliable design package despite working from preliminary drawings and incomplete vendor information.
To minimize installation costs and reduce operational disruption, Nexus developed solutions that reused existing cabling through the implementation of intermediate cable transition terminal boxes while also incorporating DC backup operation for the new breakers. This approach maintained compatibility with existing systems while supporting the operational requirements of the upgraded equipment.
Throughout the project, Nexus maintained close coordination with the client and project stakeholders, ensuring engineering decisions were aligned with schedule requirements, construction planning, and long-term operational objectives.
Outcome
By leveraging advanced 3D scanning, detailed field verification, and strategic use of preliminary drawings, Nexus successfully developed a comprehensive engineering design package that supported the client's aggressive project schedule while reducing installation risk.
The detailed design effort enabled construction planning and contractor bidding activities to move forward ahead of final vendor documentation, helping protect critical outage windows and maintain overall project momentum. The design package received positive feedback from both the client and construction contractor for its quality, level of detail, and constructability.
By addressing space constraints, identifying potential equipment interferences before construction, and developing efficient solutions for integrating new equipment with existing infrastructure, Nexus helped the client reduce project risk, improve reliability, support schedule certainty, and position the facility for successful long-term operation.
Services Provided
- Detailed engineering design for 345kV breaker replacement
- Electrical system studies and design documentation
- Single-line and three-line diagram updates
- Control schematic and wiring diagram development
- Switchyard plan and elevation updates
- High-voltage lead length analysis and recommendations
- Cable schedule updates and field verification
- Bill of materials development
- Construction scope of work development
- Project management and coordination
- Project scheduling and status reporting
- Field walkdowns and verification
- 3D scanning and modeling of existing switchyard conditions
- Constructability review and installation planning
- Preliminary and final design package development
Project Director
