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 Post subject: Arc Flash And The U. S. Navy
PostPosted: Wed Feb 01, 2012 8:22 am 
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PostPosted: Wed Feb 01, 2012 8:56 am 
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The Navy is actually how I got started in this arc flash stuff, we were installing arc flash devices in our switchgear back in the early 90's. Similar to the light sensing relays that are becoming more common in the civillian world today. My sub was one of the first to install that system.


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PostPosted: Wed Feb 01, 2012 9:07 am 
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You were one of the couple of people I was thinking of when I posted this! Sounds like you had a great intro to all all this back in the day.

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PostPosted: Mon Feb 13, 2012 1:59 pm 
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Hey Zog,

What was the sub? I was on a sub in the early 90's but never heard of or knew anything about Arc Flash at that time. Just curious, would be interesting to know the boat and if I knew anyone that served on it.

Thanks!!


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PostPosted: Tue Feb 14, 2012 7:38 am 
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LaJolla SSN-701, also early 90's. We were one of the first boats to install this system, maybe 1993?


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PostPosted: Tue Feb 14, 2012 7:42 am 
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I was on the USS Louisville SSN 724 1991-1996.


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PostPosted: Tue Feb 14, 2012 2:07 pm 
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Small world, we were usually moored to the same Pier.


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PostPosted: Tue Feb 21, 2012 8:48 am 

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Good day,
I'm a electrical officer with the Canadian government and have been tasked with Arc Flash with our fleet. I'm glad that there is mention of vessels in this form. Usually in our vessels, there is operational breakers in the vessel's control room as close as 2 feet from your back, these breakers are in a switchboard, (there is a thin steel metal door or cover) operation of the breaker can be independant of operating personnel automatic (opening or closing). Reading different articles, my conclusion would be adding some protective sensing device to each breaker, photo,heat etc. open the breaker sooner, lessen the fault time.
Please if anyone has thoughts on this I would appreciate it. Also is there a template for an arc flash analysis study, that can be presented to a contractor ?

Thanks in advance.


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PostPosted: Tue Feb 21, 2012 10:38 am 

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The template would be to include short circuit report, TCC's, single line diagram, labels, atc flash hazrad lebels etc...


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PostPosted: Tue Feb 21, 2012 12:10 pm 
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colp wrote:
Good day,
Reading different articles, my conclusion would be adding some protective sensing device to each breaker, photo,heat etc. open the breaker sooner, lessen the fault time.

Under normal operating conditions, the breaker opening time often has to be delayed to give downstream devices time to interrupt a fault. "Maintenance switches" can sometimes be added to reduce arcing time while maintenance is being performed on downstream equipment. This would not reduce the arc hazard that might occur if the breaker itself failed. To do this would require reducing the clearing time of the device upstream from the breaker.


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PostPosted: Thu Feb 23, 2012 11:23 am 

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Hello again,
I was wondering how did the sub's get a solution to there arc flash issues. Were other electrical sensing devices added to their systems to monitor for arc flash, light or temperature. And correct me if I'm wrong, there isn't a concern if the doors/covers are kept shut, while the system is in operation. Meaning if you are just walking by (not opening doors) ,there is minimal danger, and no PPE is required.
Please pass on your thoughts,
Steve


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PostPosted: Fri Mar 09, 2012 10:07 am 
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colp wrote:
Good day,
I'm a electrical officer with the Canadian government and have been tasked with Arc Flash with our fleet. I'm glad that there is mention of vessels in this form. Usually in our vessels, there is operational breakers in the vessel's control room as close as 2 feet from your back, these breakers are in a switchboard, (there is a thin steel metal door or cover) operation of the breaker can be independant of operating personnel automatic (opening or closing). Reading different articles, my conclusion would be adding some protective sensing device to each breaker, photo,heat etc. open the breaker sooner, lessen the fault time.
Please if anyone has thoughts on this I would appreciate it. Also is there a template for an arc flash analysis study, that can be presented to a contractor ?

Thanks in advance.

The control room environment you describe is not unlike some tanker ship work we have been involved with. In some configurations the Flash Hazard Boundary will extend to the limits of the control room. In our work there was an option to reduced arc flash hazard by configuring the switchboard to operate through a arc flash limiting tie breaker and that was our recommendation for any time the breakers needed to be worked on.


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PostPosted: Fri Mar 09, 2012 5:24 pm 
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Sorry if this is elemetary but just curious what the effects of the short circuit and ultimately incident energy levels are on this type of system. I would assume that they are very similar to a generator system used for emergency or backup. How does this system ground is it a floating ground at the generator? What types of tripping times does this system see and are the energy levels higher? Like I said truly just curious would appreciate the education.


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PostPosted: Fri Mar 09, 2012 5:25 pm 
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Sorry if this is elemetary but just curious what the effects of the short circuit and ultimately incident energy levels are on this type of system. I would assume that they are very similar to a generator system used for emergency or backup. How does this system ground is it a floating ground at the generator? What types of tripping times does this system see and are the energy levels higher? I know nothing of the Navy I was in the Air Force staying dry. Like I said truly just curious would appreciate the education.


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PostPosted: Fri Mar 16, 2012 11:03 am 
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FFoote wrote:
Sorry if this is elemetary but just curious what the effects of the short circuit and ultimately incident energy levels are on this type of system. I would assume that they are very similar to a generator system used for emergency or backup. How does this system ground is it a floating ground at the generator? What types of tripping times does this system see and are the energy levels higher? I know nothing of the Navy I was in the Air Force staying dry. Like I said truly just curious would appreciate the education.

Nothing really different from systems on land, except that my experience includes exceptionally well coordinated systems because the entire ship's distribution system is procured at one time from one vendor.


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PostPosted: Thu Apr 12, 2012 8:33 pm 
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I taught a 70E class at Camp David a few months ago to Navy electricians. I was one myself back in the late 80s and early 90s, and we heard nothing about arc flash back then. I am glad to see the article you posted here - the guys and gals at Camp David were very surprised by the arc flash requirements in 70E, especially since they had just been issued all new uniforms that were 50% cotton/50% polyesther. The uniforms did not have any type of arc flash rating that we could find. These were their new camo uniforms that they would wear in combat. I certainly hope that they were a special FR-type of poly, but no one there could tell me.

Thanks for the article.


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