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Time Current Curves- what am I doing wrong? 2

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Mbrooke

Electrical
Joined
Nov 12, 2012
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2,546
Location
US
I used S&C's coordinate to triple check fuse coordination on an existing system/retrofit, yet for some reason when plotted the time current curves start at 1/3 the listed fuse rating. I'm lost for an explanation as to why that would be. Even setting the preload amps to zero still gets the same results.
 
 https://files.engineering.com/getfile.aspx?folder=80138ff5-e9dd-4dcf-ae22-2cf5e32e2ebd&file=coordinaide_export20190501-221306.pdf
Without having the curves at hand to verify, my guess is that all of the fuses listed after the transformer are being applied at 4.8kV but plotted as seen from the 34.5kV side.
 
Yep, you're looking at 4.8kV fuses as seen from the 34.5kV system. I plotted the first three fuses (1 @ 34.5kV and 2 @ 4.8kV) in OneLiner and they show up very close to where you're showing them.
 
I would not have made that connection so fast- thank you yet again!
 
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