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 Post subject: MV Switchgear Fuse Holder. HCB, VCBB, or VCB?
PostPosted: Wed Mar 11, 2020 9:01 am 

Joined: Thu Jan 23, 2020 4:05 pm
Posts: 3
Hi all,

I have trouble choosing electrode configuration for a medium voltage switchgear with a fuse holder inside one of the cabinet.
i know that IEEE didn't really say what's the electrode configuration for a fuse holder is. It can be HCB where the clip is, or it can be VCB where the cable connect to the fuse. So i'm wondering what configuration you guys normally use for a fuse holder?

Thanks.
Khanh


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 Post subject: Re: MV Switchgear Fuse Holder. HCB, VCBB, or VCB?
PostPosted: Mon Mar 16, 2020 8:42 am 
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Joined: Tue Oct 26, 2010 5:00 pm
Posts: 188
Location: Maple Valley, WA.
Normally, HCB produces a larger value of arc flash energy. But you may want to be safe and try both and then take the greater value of Arc Flash energy and put that information on the AF label.

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Robert Fuhr, P.E.; P.Eng.
PowerStudies


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 Post subject: Re: MV Switchgear Fuse Holder. HCB, VCBB, or VCB?
PostPosted: Mon Mar 23, 2020 10:23 am 

Joined: Mon Aug 20, 2018 6:03 am
Posts: 9
If I may expand on Mr. Fuhr's excellent suggestion.
1) look at the direction of the current conductors feeding the arc... the force vector pushing the arc is created by those conductors. If there are clips and or lugs it may be better represented as HCB even if the cables come vertically.
2) Generally HCB vs VCB produces very similar arcing current, so HCB is the most conservative with respect to incident energy and usually arcing current as well.
3) However, if you are setting the protection tightly make sure you identify the lowest possible arcing current and ensure the protection will respond as you wish it to respond to that lower arcing current with margin for safety.
4) Regardless what model you use you want to make sure you have the right "time" in the equation!
5) If in doubt about the gap, use the largest gap that may be the case... larger gap is always more conservative.


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 Post subject: Re: MV Switchgear Fuse Holder. HCB, VCBB, or VCB?
PostPosted: Fri Mar 27, 2020 1:18 pm 

Joined: Thu Jan 23, 2020 4:05 pm
Posts: 3
Thanks all for replying. ETAP let me put in two electrode configurations and it would show the worse one. I put in HCB and VCBB.


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