Neher-McGrath
- Thread starter billyzee
- Start date
- Status
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
I use a specialized software program, whenever I need to do that kind of calculation. I think it cost the company about $2,000 for the software. It does not show the intermediate mathematical steps. You set up the model by telling it how many conduits you have, their sizes, their relative postions, the number and sizes of conductors in each, and the burial depth. It does the rest.
Are you looking for an example to see what the results look like? The results are printed in tabular format, and on a sketch of the system with ampacity numbers shown in each duct.
Are you looking for an example to see what the results look like? The results are printed in tabular format, and on a sketch of the system with ampacity numbers shown in each duct.
AmpCalc
http://www.calcware.com/
http://www.calcware.com/
Last edited:
NeherMac
NeherMac
I have a special software package called AmpCalc. We've been using it for awhile. My task is find some examples, model them in the software and make sure the results match. Its a goofy process that our client (guess who) makes us go through when using software to aid in the design process. I rather like doing this stuff sometimes because it makes me try and understand all the stuff that I was supposed to understand when pretending I understood wasn't good enough.
NeherMac
I have a special software package called AmpCalc. We've been using it for awhile. My task is find some examples, model them in the software and make sure the results match. Its a goofy process that our client (guess who) makes us go through when using software to aid in the design process. I rather like doing this stuff sometimes because it makes me try and understand all the stuff that I was supposed to understand when pretending I understood wasn't good enough.
RoberteFuhr
Member
- Location
- Covington, WA.
beanland
Senior Member
- Location
- Vancouver, WA
Finite Element Analysis
Finite Element Analysis
Rather than using software the relies on Neher-McGrath, I use a finite element analysis package and build the models. This gives me more flexibility in defining the problems and handling unususal circumstances. I use QuickField for 2D and FlexPDE for 3D modeling.
Finite Element Analysis
Rather than using software the relies on Neher-McGrath, I use a finite element analysis package and build the models. This gives me more flexibility in defining the problems and handling unususal circumstances. I use QuickField for 2D and FlexPDE for 3D modeling.
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
The package I mentioned in post 2 is also AmpCalc. I think I understand the client's request. But I don't think I have the information that would satisfy that request.
What I infer is that they want you demonstrate that the software you plan to use is, in fact, capable of accurately performing the task you give it. One way to test it is to input a known problem with a known solution. But to get the "known solution," you need to use a different method, something other than the thing you wish to test.
For example, suppose you invent a new device, and call it a "calculator." Suppose you claim that it can perform arithmetic operations. So to prove it works, you hand a long list of numbers to an accountant, and ask that person to add them up. The accountant gives you back a total (and an invoice). Independently, you use your new invention to add up the same numbers. You get the same result. You have thereby verified that your invention works.
Any example calculations I could dig out of our project files will have been done using the same AmpCalc package that you need to test. So they would not comprise a "different method."
You could do a few sample calculations using AmpCalc, and have someone else do the same calculations using a different software package (e.g., ETAP, as Bob Fuhr suggested). That could give you a valid comparison, and could satisfy the client's request. The problem with this plan is that the Neher-McGrath methodology will not necessarily give you the same answers, even with the same inputs, if you apply different analytical techniques for solving the numerous, simultaneous, non-linear equations. You may or may not get an exact match. I once tried to use AmpCalc to derive the numbers that appear in some of the NEC tables that apply to underground ductbanks. My answers were close, but not exact matches.
What I infer is that they want you demonstrate that the software you plan to use is, in fact, capable of accurately performing the task you give it. One way to test it is to input a known problem with a known solution. But to get the "known solution," you need to use a different method, something other than the thing you wish to test.
For example, suppose you invent a new device, and call it a "calculator." Suppose you claim that it can perform arithmetic operations. So to prove it works, you hand a long list of numbers to an accountant, and ask that person to add them up. The accountant gives you back a total (and an invoice). Independently, you use your new invention to add up the same numbers. You get the same result. You have thereby verified that your invention works.
Any example calculations I could dig out of our project files will have been done using the same AmpCalc package that you need to test. So they would not comprise a "different method."
You could do a few sample calculations using AmpCalc, and have someone else do the same calculations using a different software package (e.g., ETAP, as Bob Fuhr suggested). That could give you a valid comparison, and could satisfy the client's request. The problem with this plan is that the Neher-McGrath methodology will not necessarily give you the same answers, even with the same inputs, if you apply different analytical techniques for solving the numerous, simultaneous, non-linear equations. You may or may not get an exact match. I once tried to use AmpCalc to derive the numbers that appear in some of the NEC tables that apply to underground ductbanks. My answers were close, but not exact matches.
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
(Aside to Bob Fuhr) Welcome to the forum.
scottcoburn
New member
Calculation example
Calculation example
There is your example. Good luck.
{Moderator's Note: I removed the link, because the web site it takes you to has not only an example calculation, but also advertising material. If you want to get a link to that web site, then send a Private Message to the scottcoburn.}
Calculation example
There is your example. Good luck.
{Moderator's Note: I removed the link, because the web site it takes you to has not only an example calculation, but also advertising material. If you want to get a link to that web site, then send a Private Message to the scottcoburn.}
Last edited by a moderator:
- Status