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Fazlay Raabi
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Join Date: Nov 2018
Posts: 13

Fuse Selection for Distribution Line

12/11/2018 12:33 PM

What would be the best T-type fuse size for red marked branch (2-9)?

N.B: a 70-L recloser have been used in just before (in the main line) the starting of the branch .

in solution sheet they ploted all the curve and said 25T will be perfect size .i dont understand why 40T is not perfect .
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Pathfinder Tags: distribution Fuse power protection
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lyn
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#1

Re: Fuse Selection for Distribution Line

12/11/2018 3:38 PM

That would be found in the applicable electrical codes for your location, which you do not provide.

BS7671, NFP-70, maybe.

Do some research. You should have this information already if you are specify fuses!!

An anonymous forum is not the place to go.

Don't kill anybody!
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Fazlay Raabi
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#6
In reply to #1

Re: Fuse Selection for Distribution Line

12/16/2018 10:29 AM

This is a solved problem from a hand book .They didn't mention any type of electrical code to clarify .And i'm not killing man i'm trying to save
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PWSlack
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#2

Re: Fuse Selection for Distribution Line

12/11/2018 4:12 PM

Please explain why the <...they...> are not to be trusted?

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Fazlay Raabi
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#5
In reply to #2

Re: Fuse Selection for Distribution Line

12/16/2018 10:25 AM

I didn't said that they are not to be trusted . Its a solved example. I have to understand the fact to solve the other similar problems
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jack of all trades
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#3

Re: Fuse Selection for Distribution Line

12/11/2018 6:34 PM

Hint: For coordination of protection do you want the upstream recloser to trip first or do you want the downstream fuse to trip out first? Consider what happens to the load on the system if the recloser opens instead of the fuse and visa versa? Which do you want to operate first before the other?

Have another close look at the curve table paying close attention to where the fuse curves are in relation to the recloser curves.

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rwilliams
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#4
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Re: Fuse Selection for Distribution Line

12/12/2018 12:26 AM

The smaller fuse will interrupt the fault with less damage, once the recloser has attempted to clear the fault first...

Try adding the 40T fuse to the curves and it may be clearer what the risk is to the equipment and conductors
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Fazlay Raabi
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#7
In reply to #4

Re: Fuse Selection for Distribution Line

12/16/2018 10:31 AM

This sounds legit .But i already add curve of 40T fuse
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rwilliams
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#8
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Re: Fuse Selection for Distribution Line

12/16/2018 11:01 AM

I see it now, it looks like they both coordinate, just less damage and less upset to power system stability
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PWSlack
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#9
In reply to #8

Re: Fuse Selection for Distribution Line

12/17/2018 5:25 AM

Avoiding <...damage...> is the priority.

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rwilliams
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#10
In reply to #9

Re: Fuse Selection for Distribution Line

12/17/2018 11:26 AM

At the fault level that the 20T doesn’t coordinate, you probably have more than a tree branch on the line, so minimize additional damage and clear it off, send out the line crew
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Users who posted comments:

Fazlay Raabi (3); jack of all trades (1); lyn (1); PWSlack (2); rwilliams (3)

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