Crane Power Rail Arc Flash

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chelin

Member
Location
St. Paul, MN
Does anyone knows how to model a crane power rail for arc flash calculations?

I need to calculate the arc flash levels for an 800 ft crane power rail (e.g. warehouse automated cranes). My concern is that the arc flash level at one end of the rail is not going to be the same as compared to the other end due to short circuit level difference.

Do I need one sticker for the whole rail? Can I calculate the arc flash using only the distance at the feeder connection? How do I model a rail in a program? (I use SKM)
 
zog

zog

Senior Member
Location
Charlotte, NC
chelin said:
Does anyone knows how to model a crane power rail for arc flash calculations?

I need to calculate the arc flash levels for an 800 ft crane power rail (e.g. warehouse automated cranes). My concern is that the arc flash level at one end of the rail is not going to be the same as compared to the other end due to short circuit level difference.

Do I need one sticker for the whole rail? Can I calculate the arc flash using only the distance at the feeder connection? How do I model a rail in a program? (I use SKM)
Click to expand...

I hope it isn't a DC crane, there are no DC arc flash equations.
 
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jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
We calculate the values at the beginning and the end. We recommend using the worst case values only.

But you need to be careful when using software defaults:
The gap (spacing of the conductors) used in your equations needs to be examined for adequacy.
The "arc in open air" formulas should probably be used, although "arc in a box" values are usually more severe.
The arc duration must be considered, it may be unlikely for an employee to evacuate the arcing zone in 2 secs or less.
 
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