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Anonymous Poster

Bolted Fault Current

02/01/2010 4:11 PM

Can someone explain what bolted fault current is?
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JRaef
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#1

Re: Bolted Fault Current

02/01/2010 4:26 PM

A Phase to Phase short circuit, as opposed to a Ground (Earth) Fault which is Phase to Ground.

I always like to think of a bolt dropped into a distribution panel bus bar system.. Probably too short to make a connection to ground, but long enough to touch two bus bars.

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msamad
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#2
In reply to #1

Re: Bolted Fault Current

02/01/2010 5:08 PM

One of the ways the electrical faults are categorized based on the presence of air in the fault circuit path. If the path contains air (a short distance of air), the fault is called arcing fault, otherwise the fault is called bolted fault. For bolted fault, the fault impedance is considered negligible (very low). On the other hand, because the high impedance of air, the arcing fault current is always lower than the bolted fault. Arcing fault releases enormous amount of energy to the air media and causes 'Arc flash' which produces very high temperature (greater than 5000 degree F). So, arcing fault is more dangerous than bolted fault. For the short circuit current calculation, the bolted faults are considered.

See the links below for more details:

http://www.squared.com/us/services_support/squared_services.nsf/LookupFiles/0613NA0302.pdf/$file/0613NA0302.pdf

http://www.efcog.org/wg/im/Events/07_Fall_Meeting/presentations/Tuesday-10-22-07/T-6%20J%20WEIGEL%20IMWOG%20Las%20Vegas%20%20AF%20Seminar%20Nov%2007.pdf

- MS

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kellytshort
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Join Date: Jan 2010
Posts: 13
#3
In reply to #2

Re: Bolted Fault Current

02/01/2010 6:52 PM

Love the foot not msamad. Sorry for off-topic but I noticed your from Houston and I just took a job their and was wondering how the market is their? What do you think of houston so far. Sorry again if this is too far of topic or weird just curious.
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rasam.syamsudin
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Join Date: Dec 2009
Location: Jakarta 12130 Indonesia
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#4

Re: Bolted Fault Current

02/02/2010 9:13 AM

as the name applied, a fault current occurred when three phase are bolted together. In practical it was happened when energizing a system while the system being shorted and grounded for maintenance purpose.

Bolted fault current is a maximum fault current which is calculated by assumption that zero impedance at short circuit point.

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Anonymous Poster
#5

Re: Bolted Fault Current

02/05/2010 5:21 PM

... I kinda get it... still a little fuzzy... sometimes hard for me to paint a picutre... but how would I calculate bolted fault current?
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Anonymous Poster
#6
In reply to #5

Re: Bolted Fault Current

02/05/2010 7:27 PM

.... The same way you calculate short circuit current.
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