What is the practice for the use of arc detection relay trip time in the arc incident energy?

Mar 8, 2018
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#1
Hi everyone,

What is the practice for the use of arc detection relay trip time in the arc incident energy calculations? NFPA-70E recognized arc detection relay but kept under "Other Methods" as opposed to "Incident Energy Reduction Method". Does this means the arc flash relay tripping time should not be used for the arc incident energy calculations?

Please help.

I didn't find the right solution from the Internet.

Thank you.
 
#2
We believe that arc detection should be included in the arc flash study ONLY if an operator is unable to deactivate it. If it can be deactivated (for whatever reason), the greater tripping times should be considered.

Somewhat similarly - although certain devices have a maintenance mode switch, we generally do not model the maintenance mode as workers may erroneously forget to activate it. We will make an exception if the client specifies it after we have provided our recommendations.