CPAU selected Burns & McDonnell on the strength of its proposed alternatives. During a bid clarification meeting, we suggested an alternative to the base bid that would use a dead tank circuit breaker with bushing current transformers (CTs), as well as a new transmission line dead-end structure accommodating three single-phase potential transformers (PTs) and a manually operated V-type disconnect.
The dead tank gas circuit breaker offered several advantages over the live-tank base proposal. Dead tank breakers have a shorter profile and are installed lower to the ground, which can be attractive in a seismically active area like the San Francisco Bay Area. The addition of the on-site disconnect provides a visual open point, which increases safety and access for construction and maintenance staff. Including bushing CTs allows for better protection zones to be implemented, which improves protection coordination.
Together, these attributes provided an improved installation within the same bay footprint and on a schedule that was only slightly longer than the live tank breaker base bid.
We applied our extensive experience working on substations and with engineer-procure-construct (EPC) project delivery to manage all aspects of design and construction with high efficiency. We implemented an array of project controls and change management to help CPAU complete the project successfully.