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 Post subject: Motor Controls
PostPosted: Fri Feb 22, 2019 8:05 am 
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What electrode configuration would you use?


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 Post subject: Re: Motor Controls
PostPosted: Fri Feb 22, 2019 9:33 am 

Joined: Tue Dec 31, 2013 12:19 pm
Posts: 37
Fuse clips could be VCBB or HCB. At the breakers and motor starters it is VCBB. All else being equal, if you run the calc's on both VCBB and HCB, HCB will give you the higher incident energy. So I would use HCB.


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 Post subject: Re: Motor Controls
PostPosted: Mon Feb 25, 2019 5:01 am 
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vCBB unless the dimensions work out to shallow which this has to be close. Due to enclosure sjze VOA might be more appropriate though. When does CF reduce VCB 5o equal VOA?


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 Post subject: Re: Motor Controls
PostPosted: Tue Mar 05, 2019 10:00 am 
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I tried varying box sizes with the IEEE1584 Excel Calculator and found that with 480V, 20kA bolted fault, 1" gap, 24" working distance, 200 ms arc duration, VOA gives 2.15 cal/cm². Increasing box size from 20"x20" to 60" x 60" in 5" increments, results in IE reducing from 4.56 cal/cm² to 3.44 al/cm² at 50" x 50" and not reducing for larger sizes.

Most likely that interpolations too far beyond the tested sizes to not result in values approaching the open air case.


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 Post subject: Re: Motor Controls
PostPosted: Tue Mar 05, 2019 11:07 am 
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jghrist wrote:
I tried varying box sizes with the IEEE1584 Excel Calculator and found that with 480V, 20kA bolted fault, 1" gap, 24" working distance, 200 ms arc duration, VOA gives 2.15 cal/cm². Increasing box size from 20"x20" to 60" x 60" in 5" increments, results in IE reducing from 4.56 cal/cm² to 3.44 al/cm² at 50" x 50" and not reducing for larger sizes.

Most likely that interpolations too far beyond the tested sizes to not result in values approaching the open air case.


The adjustment stops at 1244 mm.


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 Post subject: Re: Motor Controls
PostPosted: Mon Apr 01, 2019 11:14 am 

Joined: Mon Nov 24, 2008 6:42 pm
Posts: 5
Location: Nashville, TN
Jim,
I mean no disrespect, but you are shown as Vice Chair of the IEEE 1584-2018 Committee.

Why are YOU asking us what electrode configuration this is? You should be telling us.

This is where I am frustrated w/ the new IEEE 1584-2018. You didn't make any effort to give us real-world examples of your laboratory test configurations. You should have provided a table showing all the common real-world examples of VCB, VCBB, HCB, etc. configurations.

How am I as an end-user supposed to know what your intentions were? You guys who developed this standard are the only people in the world that can answer YOUR question. All this standard did was create more CONFUSION.


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 Post subject: Re: Motor Controls
PostPosted: Fri Apr 05, 2019 3:48 am 

Joined: Mon Aug 04, 2014 5:19 pm
Posts: 15
Yes I second the motion. The latest IEEE 1584 created a "Tower of Babel" for the practicing engineer and it seems like everyone will have a different interpretation on the electrode configuration.
Jim


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 Post subject: Re: Motor Controls
PostPosted: Tue Jul 13, 2021 10:15 am 
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Joined: Sat Apr 04, 2009 9:50 pm
Posts: 117
Location: San Antonio, TX
Jim:

I agree with all the engineers in this forum that have the feeling that the new requirements for entering data of enclosure sizes and electrode configurations is based on non-real-world cases and very confusing.

Now, the electrical engineers performing these calculations are confused about how to apply these concepts in real-world cases.

And what is worst, the people that were involved in giving us these standards, apparently are also confused because they are asking us, the ones performing the studies, what is our opinion about a particular real case.

Can you please translate these enclosure sizes and electrode configuration from a theoretical situation to real-world cases? You do not need to show all possible cases, that would be unreasonable, but the main situations?

Thanks.


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 Post subject: Re: Motor Controls
PostPosted: Sun Jul 18, 2021 10:42 am 
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RECS wrote:
Jim:

Can you please translate these enclosure sizes and electrode configuration from a theoretical situation to real-world cases? You do not need to show all possible cases, that would be unreasonable, but the main situations?


The original post was from just a few months after the 2018 edition was issued.

No doubt this is a more complex model than the 2002 edition. When the 2002 edition was published, it was a new calculation model and users where initially uncertain of what to do with it. (which is why I began this forum back in 2007) Then people began publishing technical papers about experiences using the model and the application became more routine.

The 2018 model created a similar situation and as before, technical papers where presented based on user’s analysis and application experience. Many software providers had active representation on the committee and subsequently integrated this into their software complete with defaults which can be changed if someone wants to.

The "theoretical" part of this - electrodes in a box etc. is for test repeatability within a controlled environment. The different electrode configuration where the result of what was learned since the 2002 standard.

Some application guidance for real world cases IS found in Section 6 of the 2018 edition of IEEE 1584 which includes photos of equipment to identify VCB, VCBB, HCB etc.

It's now been almost 3 years since the 2018 standard was published and most that were previously familiar with arc flash studies have adapted to the 2018 model which provides much more modeling flexibility.


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