Solution
This particular mining operation began using SEL-501 Dual Overcurrent Relays in their substations in 1994. They began adding arc-flash mitigation capability in 2000 by installing SEL-751 Feeder Protection Relays and SEL-710 Motor Protection Relays configured with arc-flash detection.
When the arc-flash event actually occurred, it reinforced the importance of arc-flash safety and piqued their interest in how arc-flash mitigation works. “The total [incident] energy was significantly minimized by having the arc-flash technology,” said the engineer. “It was clear [to the 30 electrical contractors] that this technology was good to have—it’s not just academic.”
Diagram depicting a representative arc-flash detection scheme using overcurrent and light sensors (LSs) for fast and secure arc-flash protection.
“The equipment was installed to protect personnel, but [it was clear that] the SEL relays also protected our equipment from potentially devastating damage.”
Results
Heightened Awareness. After using arc-flash mitigation technology for several years and never having an event, the lead engineer and his associates sometimes wondered if their investment in arc-flash detection was truly necessary. However, the mitigation of the potentially deadly arc-flash event proved the technology's worth.
Retrofit Application. The mining operation now plans to add arc-flash mitigation to its remaining switchgear equipment. According to the electrical engineer, “[The] older gear doesn’t have any venting, so it’s even more important to have arc-flash protection.”