Arc Flash 70E Calculations(simple Explaination)
- Thread starter yoopersup
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charlie
Senior Member
- Location
- Indianapolis
Re: Arc Flash 70E Calculations(simple Explaination)
Bob, fair enough.
Bob, fair enough.
Re: Arc Flash 70E Calculations(simple Explaination)
The reccomendation I've seen is to do the arc flash calculation at the Max fault current, and another calculation at 80%. Then you use the worst case of the two. Finally, you increase the result some more based on a table listing differnet voltages and types of enclosure (box or open). This last step is because some experiements showed arc fault energies higher than calculated values.
Steve
The reccomendation I've seen is to do the arc flash calculation at the Max fault current, and another calculation at 80%. Then you use the worst case of the two. Finally, you increase the result some more based on a table listing differnet voltages and types of enclosure (box or open). This last step is because some experiements showed arc fault energies higher than calculated values.
Steve
zog
Senior Member
- Location
- Charlotte, NC
Re: Arc Flash 70E Calculations(simple Explaination)
for systems less than 1000V an arc flash will not sustain itself at less than 38% BF current, which also will take the longest to clear due to the inverse time charcteristics of protective devices.
Turns out that for for systems the lower fault (38%) causes the most intense arc flash. The basic equitions are actually simplified versions of the actual equaltions that can be found in the back of your 70E.
for systems less than 1000V an arc flash will not sustain itself at less than 38% BF current, which also will take the longest to clear due to the inverse time charcteristics of protective devices.
Turns out that for for systems the lower fault (38%) causes the most intense arc flash. The basic equitions are actually simplified versions of the actual equaltions that can be found in the back of your 70E.
pierre
Senior Member
- Location
- Westchester County, New York
Re: Arc Flash 70E Calculations(simple Explaination)
I think sometimes in our mad world we forget the bottom line. That is this requirement has been put forth to help protect the installer in the field from injury or death.
Yes for those involved in the calculation and theory there are some complications , but for now we still need to protect these individuals.
What we need to do is introduce the idea/concept to them and how/when they need to protect themselves.
In the interim, the "brains' can work out the details.
I think sometimes in our mad world we forget the bottom line. That is this requirement has been put forth to help protect the installer in the field from injury or death.
Yes for those involved in the calculation and theory there are some complications
, but for now we still need to protect these individuals.What we need to do is introduce the idea/concept to them and how/when they need to protect themselves.
In the interim, the "brains' can work out the details.
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