cal per cm squared

Status
Not open for further replies.

zog

Senior Member
Location
Charlotte, NC
You need to know the available fault current and clearing time of the overcurrent protective device upstream for each point, you also need to know the working distance and the distance of the elctrode gap. Put all of that info into some engineering software and let it run different senarios of fault current and clearing times for different arc impedences and the highest incident energy (in cal/cm2 at a certian working distance) will be calculated.
 

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
. . . cal per cm squared rating. . .
Panels do not have ratings of this nature. Panels are rated for the maximum voltage that can be applied, for the maximum continuous current they can handle, and the maximum fault current they can take, but not for the amount of arc flash energy they can release or they can survive. But if you are asking what information should be placed on the arc flash label, or what PPE must be worn in order to perform live work on the panel, then I refer you back to Zog's answer.
 

dshelley

Member
I am doing a Arc flash hazard assesment and i need to know if any one knows how to
get the cal/cm2 flash hazard at 18 " on a 480v 2000 amp mdp
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
You have to do what Zog said in post #2. You have to do a full study of the system to get that information.
 

iceworm

Curmudgeon still using printed IEEE Color Books
Location
North of the 65 parallel
Occupation
EE (Field - as little design as possible)
I am doing a Arc flash hazard assesment and i need to know if any one knows how to
get the cal/cm2 flash hazard at 18 " on a 480v 2000 amp mdp

The short answer is, "Yes".

To add to the already excellent posts:
I recommend reading NFPA 70E and IEEE 1584.

And as Zog mentioned, if this is "for hire", a lot of states consider this engineering and require a PE stamp.

ice
 

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
. . . I need to know if any one knows how to get the cal/cm2 flash hazard at 18 " on a 480v 2000 amp mdp
Yes, I know how to do it. I would start by opening up the company?s licensed copy of the SKM Power Tools software. I would create a model of the electrical distribution system, including the utility transformer, the service conductors, the panels and transformers throughout the facility, and the feeders connecting all components. I would input the conductor lengths and wire sizes for all feeders. I would input the model numbers and trip settings of all overcurrent devices. And I would input the horsepower and other ratings for all large motors installed in the facility. Then I would review the data, to see if I have missed anything. Next, I would hit the ?Arc Flash Analysis ? Go? button, and print the results. Then I would review the results to verify that they appear to be consistent with the input data. Finally, I would write a report that documents the entire process, and apply my PE seal and signature to the document. Oh, actually, that would not be the final step. I would still have to send the invoice for my work.

 

eric9822

Senior Member
Location
Camarillo, CA
Occupation
Electrical and Instrumentation Tech
Lots of good posts here. This type of thing is typically done by consulting engineering firms and not by in-house electricians or engineers. Gathering the information required can be very time consuming especially if single line drawings don't exist or are inaccurate. We have a very large power distribution system where I work and we have a contract engineeering firm perform our studies every 3 years or whenever significant changes are made to the system. Based on the size of the system we have I think the cost is very reasonable. I suggest you pursue that avenue versus trying to do it yourself. Charlie is a very knowlegable resource on this forum and it sounds like he provides this service. I can also provide the name of the firm we use. If I were you I would PM Charlie, me, or someone else and get some contact information.
 

jghrist

Senior Member
Yes, I know how to do it. I would start by opening up the company?s licensed copy of the SKM Power Tools software. ...
But that's because you understand the arc flash hazard problem and the analysis. I would not suggest that the OP buy SKM and attempt this on his own without enough study to understand what he's doing.
 
Status
Not open for further replies.
Top