Case study: Emergency Distribution System Upgrade

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Emergency Distribution System Upgrade

Customer: Port of Seattle

Project Location:Seattle, Washington

The Port of Seattle wished to replace four 35-year-old and one 20-year-old 4.16KV, 480Y/277 volt emergency distribution centers. Each of the five emergency distribution centers were originally made up of a 4.16KV load break switch, transformer and branch circuit panelboard, all within a single unit. The new equipment was made up of separate components, including a medium voltage incoming switch, step-down transformer, and a distribution panelboard. A low voltage transfer switch was added at each location, allowing emergency loads to be fed from an alternate normal power source during maintenance activities.

The Challenge

The addition of a transfer switch into the existing system, at each of the five emergency distribution centers, created a significant increase in the available fault level, due to the addition of the normal source (to be used for maintenance and testing only). The project did not have funding for replacement/upgrading of downstream underrated equipment.

The critical nature of this Life Safety system dictated zero down time

The Solution

An Isolation transformer was added into the normal feeder just prior to the transfer switch to act as a choke and limit the available fault.

Harris Group provided extensive field investigation and recording of the existing emergency distribution system including all associated feeders and equipment. All feeders and equipment were located and detailed on the construction drawings. A detailed construction sequence was developed in coordination with detailed construction phasing included on the construction drawings.

The Benefits

Harris Groups detailed construction sequence contributed to limiting interruptions of the emergency power distribution system to planned/scheduled outages only. We met the goal of zero down time for construction of this life safety system. Harris Groups code review for this life safety system was performed during concept design and identified multiple design challenges associated with code requirements in the National Electrical Code. The upfront code analysis allowed us to address the associated challenges early in the design process through coordination with the Port of Seattle and the Inspectors/Authorities Having Jurisdiction.

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Overview Case Studies ...more White Papers Contacts	Emergency Distribution System Upgrade Customer: Port of Seattle Project Location:Seattle, Washington The Port of Seattle wished to replace four 35-year-old and one 20-year-old 4.16KV, 480Y/277 volt emergency distribution centers. Each of the five emergency distribution centers were originally made up of a 4.16KV load break switch, transformer and branch circuit panelboard, all within a single unit. The new equipment was made up of separate components, including a medium voltage incoming switch, step-down transformer, and a distribution panelboard. A low voltage transfer switch was added at each location, allowing emergency loads to be fed from an alternate normal power source during maintenance activities. The Challenge The addition of a transfer switch into the existing system, at each of the five emergency distribution centers, created a significant increase in the available fault level, due to the addition of the normal source (to be used for maintenance and testing only). The project did not have funding for replacement/upgrading of downstream underrated equipment. The critical nature of this Life Safety system dictated zero down time The Solution An Isolation transformer was added into the normal feeder just prior to the transfer switch to act as a choke and limit the available fault. Harris Group provided extensive field investigation and recording of the existing emergency distribution system including all associated feeders and equipment. All feeders and equipment were located and detailed on the construction drawings. A detailed construction sequence was developed in coordination with detailed construction phasing included on the construction drawings. The Benefits Harris Groups detailed construction sequence contributed to limiting interruptions of the emergency power distribution system to planned/scheduled outages only. We met the goal of zero down time for construction of this life safety system. Harris Groups code review for this life safety system was performed during concept design and identified multiple design challenges associated with code requirements in the National Electrical Code. The upfront code analysis allowed us to address the associated challenges early in the design process through coordination with the Port of Seattle and the Inspectors/Authorities Having Jurisdiction.