Ballinger’s electrical engineers are celebrating the completion of a long-term project to replace the 15 kV medium-voltage power switchgear in Penn Medicine’s Hospital of the University of Pennsylvania (HUP).
The University of Pennsylvania’s School of Medicine was the nation’s first medical school and remains a renowned center of research and clinical excellence. HUP is the oldest university-owned teaching hospital in the country and sees over 72,000 patients per year. Ballinger has worked with them over the last ten years on the planning and implementation of several major electrical power projects, with the end goal of replacing the 15 kV medium voltage main service entrance switchgear for this prestigious institution. Chief Electrical Engineer, Russ Neithammer explained Ballinger’s approach to this monumental project.
What was this project all about?
RUSS NEITHAMMER: The overall goal was to upgrade the over 70-year-old 15 kV medium voltage utility service entrance switchgear, leading to an improvement in overall reliability, simplified maintenance, and a reduction in exposure to catastrophic failure. We started with a feasibility study in which we identified a number of approaches to replacing the switchgear and to upgrading lighting, HVAC, fire sprinkler protection, and egress provisions in the hospital’s main electrical equipment vault to meet current code requirements and to be consistent with other University electrical service facilities.
What sort of options did you consider?
RN: Each approach had its pros, cons, and risks. For switchgear replacement, we considered many options. For example, we looked at a vacuum circuit breaker retrofit into existing switchgear cubicles, installing the new switchgear in the existing location, and installing it in an adjacent transformer vault location.
How did you decide which approach to take?
RN: It was essential that there be no disruptions to hospital operations in the process of replacing the service entrance switchgear. This meant that we had to have a design that minimized the time required for any single outage as we changed over from the old switchgear to the new, while also allowing for the option of temporarily backing out to existing conditions if we encountered problems during any of the outage work. Continuity of operations and constructability were the key drivers that informed all major design decisions.
That sounds complex. What methods did you use to make that possible?
RN: We designed the switchgear installation with constructability in mind right from the start. The design option that resulted in the least amount of risk to hospital operations was the one that allowed for installation and energization of the new switchgear in the adjacent transformer vault before removal of the old. This allowed us to move loads from the existing to the new switchgear via separate, sequential outages for each of the feeders.
The initial challenge was that before we could address replacement of the main switchgear, the active 2400V transformers in the transformer vault had to be removed from service. This meant that the entire existing 2400V distribution system (a holdover from the early 1900’s) had to be eliminated. We accomplished that by executing two predecessor enabling projects. First, we replaced the 2400V switchgear and transformation (to 480V) in the Dulles building portion of the HUP complex. Our second enabling project involved the construction of a new building that houses transformation (to 480V) and distribution to the three oldest buildings of the HUP complex. As with the replacement of the main substation, each of the enabling projects had its own constructability issues, which were addressed in a similar manner to the main substation project, i.e., install and energize the new equipment before removing the existing equipment. Completing the enabling projects eliminated all loads on the existing 2400V transformers, thus allowing them to be removed from the transformer vault and freeing up the space we needed to completely install and energize the new switchgear and move the feeders.
With an empty transformer vault, construction work leading to installation and energization could go forward, requiring only two short utility outages to tie in and energize the new switchgear and make it ready to accept load as the feeder moves were executed.
What takeaways do you have after 10 years on this project?
RN: Overall, communication throughout the process was the key to executing the project with minimal disruption to hospital operations. The design and construction staff, operations staff, clinical staff, construction manager, design assist electrical contractor, design engineer, and PECO (the electrical utility serving HUP) were all involved throughout the entire process. Likewise, although this project had a heavy electrical focus, architecture and all of Ballinger’s engineering disciplines played significant roles.
Approaching the project with this level of communication meant that the design constructability was understood by all parties. This understanding led to detailed outage planning for the best possible coordination with hospital operations. The result was a process with minimal design changes or surprises and a project executed on-time and well within budget.