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Substation Expansion: Davis Substation’s Transformer T4 and Bus 4 Addition Project

Project Overview

As part of the United Power Davis Substation project, NEI provided electrical engineering and commissioning expertise for the Transformer T4/Bus 4 Addition Project. This project was crucial for supplying power to essential facilities at a large industrial customer with extremely high outage costs, facilitating remote gas drilling activities, and catering to nearby residential areas, highlighting NEI’s ability to balance the intricate demands of large-scale projects with the needs of both industrial operations and local community needs.

Challenges and Solutions

Integrating a new main power transformer (MPT), T4, additional 15kV feeders, and new meter and control panels for all three 15kV buses and one 69kV bus into the existing infrastructure while maintaining continuity of service from Davis substation was a key challenge. Our approach demonstrated innovative engineering and strategic planning. Careful planning and sequence of operations for panel integration, wiring, and commissioning were required to maintain continuity of service for energized circuits. Existing 15kV buses 1 and 2 and 69kV bus 3 all had to remain in service during the integration and expansion.

Technical Project Highlights

The addition of Main Power Transformer T4, a 115-13.2kV, 90MVA unit, significantly expanded capacity and reliability for local industrial customers. The project also consisted of adding dual, 3000A, 15kV underground cable tie feeds from the new bus 4 to existing buses 1 and 2 to support plant operations in the event of a loss of either T1 or T2. With the tie feeds, buses 1 and 2 could also support bus 4 loads in the event of a loss of T4. Key additions included a 4000A, 15kV main breaker, five 1200A, 15kV feeder breakers, four 3000A, 15kV tie circuit breakers and new meter and control panels for all four main buses providing enhanced monitoring and control.

Phase Completion and Continuity

The Davis Substation Transformer T4/Bus 4 Addition project was executed in phases to ensure uninterrupted service. NEI was able to perform work and testing on the T4/Bus 4 side while T1 and/or T2 served critical loads for the large industrial customer. Extra precautions and care needed to be taken to ensure that bus 1 and bus 2 continuity of service were not affected during T4/bus 4 construction, wiring, relay panel integration, testing, and commissioning.

Featuring a six-breaker, 115kV ring bus arrangement and a main-tie-main configuration of transformers, the project enhanced power distribution reliability and load growth. The addition of transformer T4 was crucial, improving operational reliability and meeting increasing energy demands without service disruption.

For innovative and reliable electrical engineering solutions, reach out to our expert team at NEI.