Better safe than sorry

Arc Protection System can save lives

Arc Flashes

Arc flashes are a serious concern in the electrical industry.  They result from a fault in an electrical system where a high voltage shorts rapidly to ground.  The resulting arc plasma can exceed temperatures of 35,000 °F and the energy released can vaporize copper conductors, melt steel barriers, and create an explosion as the plasma expands outwards with extreme force.  Workers and operators in the vicinity of these arc faults are exposed to explosive, high temperature forces which can lead to serious injury or death.

The Event

ABB had assisted in the upgrade a line-up of 13.8kV metal clad switchgear at a major university in the Northeast United States.  The existing gear was installed in 1987 and was an outdoor design with a common aisle between two rows of switchgear and enclosed in a NEMA 3R enclosure.  An ABB REA Arc Protection System had been added as part of the upgrade, three months before the event occurred.  On the day of the event, six people were inside the enclosure, touring the completed project, when an arc fault occurred in one of the switchgear line-ups.

The Result

An arc fault of this magnitude would normally have severely damaged the switchgear line-up and caused injury or death of the people inside the enclosure.  Instead, the REA relay system did exactly what it was designed to do and cleared the fault by opening the source breaker in 50.2 milliseconds.  The arc light and fault current were sensed by the REA system in less than 2.5 milliseconds and the breaker opened in 48 milliseconds.  Instead of severely damaging the gear, the REA system minimized the impact to the equipment to where it could be fully restored in less than 12 hours.  More importantly, all six people walked out alive and uninjured.

The Bottom Line

It’s easy to understand why this story made such an impact on me.  Upgrading an existing line-up of switchgear by adding the REA Arc Protection System can have huge benefits.  Equipment damage can be minimized, power restoration can occur quicker, and lives may even be saved with this technology.   Even though I wasn’t there to witness the event in 2010, I’m also now a true believer in the benefits of the solution.

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About the author

Jon Rennie

I am head of the distribution automation and components business in North America. Our business has a long history of providing world-class products to the electrical distribution market. We are a leading supplier in North America and we are always working on new ways to better serve our customers.
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