The recently upgraded power system at Rex Hospital in Raleigh, N.C., was designed to ensure seamless delivery of normal and emergency power to the 660-bed facility, according to an article on the Consulting-Specifying Engineer magazine website. The hospital’s design team, led by Mike Raynor, director of facility and construction services, wanted a fail-safe emergency power system that would serve the facility’s electrical power needs for the next 30 years.
Raynor's team designed the system to provide the hospital with an emergency power system with more capacity, reliability, redundancy, and flexibility than the system it replaced, which was installed in the mid-1980s.
Rex Hospital’s emergency power system upgrade included replacing three 1.25 MW generators with two new 4,160-V, 1,800 rpm, 3.0 MW units (0.8 power factor). An existing 2.25 MW generator that matches the operating voltage of the new units was retained, the article said. The generators are capable of paralleling with each other as well as with the utility source.
The hospital’s previous backup power system was the closed-transition type. The upgraded system retained that configuration to avoid a service interruption when the feed switches from utility power to generator power (when both sources are available). The existing utility substation at the hospital was replaced, and new switches and switchgear were relocated from cramped quarters in the main hospital building to a newly constructed central energy plant, according to the article,.
Another automatic transfer switch was added to protect the hospital’s data center. When the generators are up to speed, an outdoor switchgear arrangement fed by the utility’s outdoor transformers allows the hospital to disconnect from the utility either manually or automatically.
Read the article.