Arc-Flash Basics
What is an arc-flash hazard?
According to the National Fire Protection Association (NFPA) 70E: Standard for Electrical Safety in the
Workplace, an arc-lash hazard is “a source of possible injury or damage to health associated with the
release of energy caused by an electr...
Configuration
How is arc-flash mitigation configured with SEL protective relays? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
What is the maximum number of arc-flash sensors I can connect to an SEL relay?. . . . . . . . . . . . . . . . 6
Light Sensors
Why do I need light sensors? Isn’t the overcurrent element in a protective relay sufficient to
sense when an arc-flash event occurs? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
How does the SEL light-sensing technology work? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
How do I know that the arc-flash-sensing technology will continue to work over time?
Do I test the sensors periodically to verify that they’re working? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
How do I test the arc-flash sensors during commissioning to verify that they’re in
working order? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
When should I use the bare-fiber sensor vs. the point sensor? Can I mix and match them
on the same relay? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Has there ever been an arc-flash event where the arc-flash sensors were destroyed
before they signaled the relay?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Does SEL sell or provide the necessary tools to cut and install arc-flash fiber-optic cabling?. . . . . . . 8
Installation
Where do you recommend placing the arc-flash sensors in the compartment? . . . . . . . . . . . . . . . . . . . 8
Are SEL light sensors vulnerable to dust?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
How does SEL recommend adjusting the sensitivity of the sensors? . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
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