When the Los Angeles Department of Water and Power (LADWP) needed to replace some of its outdated oil breakers in 2017, Circuit Breaker Sales (CBS) was awarded the three-year contract to provide vacuum retrofill breaker systems inside pre-existing concrete vaults. The initial order in 2018 was for eight units. Satisfied with the work, in 2019 LADWP returned to CBS and ordered an additional 24 custom-designed breaker retrofills.
While the construction of the existing switchgear was similar at each substation, substation designs varied greatly and no cubicles were identical. The vacuum systems had to replace oil circuit breakers in cubicles varying in size by as much as 24 inches in height and nearly that in width.
Even the wall openings for the mechanical operators were a motley mix of shapes and sizes, making it difficult for employees to standardize a single design. LADWP required one universal system that would work in all cubicles, regardless of size, and that could be installed quickly. The design also needed to meet seismic specifications and incorporate a voltage rating increase from 5 to 15 kV.
To meet LADWP’s unique needs, CBS partnered with LS Industrial Systems (LSIS), which designed and produced the compact vacuum circuit breakers used on the project. Meanwhile, CBS engineers developed the mechanical assembly — which included an adjustable platform system to mount the LSIS breakers, along with a steel through-wall solution to allow for manual operation and mechanical maintenance of the circuit breaker — and an adjustable mount for the multi-ration current transformers. CBS also worked with DK Controls to produce UL-certified controls that integrate flawlessly with the customer’s existing system.
The utility’s upgrade from oil breakers to modern vacuum breakers was a major improvement in technology. The project solved obsolescence problems, simplified maintenance, increased performance and ratings, and improved safety, all while maintaining the existing control interface.
The contract for this job is still current, and LADWP has plans renew the existing contract to retrofill more than 500 additional oil circuit breakers in the coming years.