Fuse design for Summit ensures safer installation and operating conditions

Employees at the Oak Ridge Leadership Computing Facility (OLCF) who have been around long enough to witness multiple supercomputer installations can tell you that each installation brings with it challenges as unique as the systems themselves. Tasked with providing basic life support like cooling and power for these leadership-class systems, OLCF staff are experts at innovating solutions for unforeseen problems.

Rick Griffin’s fuse design for Summit ensures not only a safer working environment but will also minimize downtime for Summit in the event of electrical failures.

Rick Griffin, lead project electrical engineer for OLCF systems, is responsible for solving one such challenge through a fuse design that ensures a more reliable and safe electrical supply for the OLCF’s newest supercomputer, Summit. With an estimated peak power consumption of 15 megawatts, Summit will be a powerhouse not only in terms of computing ability but also in terms of the electricity pumping through it.

In the early stages of Summit’s installation, Griffin recognized that the electrical breakers in the system’s cabinets would not be sufficient should a short circuit occur inside a cabinet.

“The potential for an electrical hazard was too great, so I began developing a fault current protection mechanism,” Griffin said. He also indicated that Summit must meet existing US electrical codes, ensuring that overcurrent protection devices are rated to withstand available fault currents.

Electrical events such as arc flashes rapidly release electrical energy that can damage system components and pose a safety hazard to nearby workers. To prevent unsafe operations, Griffin placed fuses upstream of the cabinets that limit the amount of energy released in the event of fault, electrical arc, or arc flash.

Before the fuses could be installed, they were tested by a nationally recognized testing laboratory to show they would limit fault current in this arrangement. Griffin worked with the fuse and breaker manufacturer and computer vendor to get this accomplished.

Griffin’s fuse design has already paid off, ahead of Summit’s deployment later this year. An IBM subcontractor recently experienced a small electrical arc while plugging in a computer node during Summit’s installation, and Griffin’s fuses operated as planned, rendering a potentially hazardous discharge into just a small spark.

The fuses also isolate electrical problems to a single computer cabinet, preventing them from spreading to a full electrical panel and thus additional cabinets, which minimizes downtime for the system and OLCF researchers.

“Rick’s experience and electrical designs continue to be invaluable,” said Stephen McNally, OLCF operations manager. “The upstream fuses he included in Summit’s infrastructure ensured the exact scenario we want to occur in the event of an arc flash—minimal discharge and no harm to the individuals near it.”

The OLCF is a US Department of Energy (DOE) Office of Science User Facility located at Oak Ridge National Laboratory.

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