My coop is presently planning to use our existing WindMil (Milsoft) model to perform an Arc Flash Hazard Assessment for our distribution substations and feeders. Our "sister" G&T has asked us if we could assist them in performing a study for a 40 MW gas turbine plant and a 120 MW hydro plant we operate. I have a query in to Milsoft as to whether or not we can correctly model & analyze these plants. My forum questions are:

(1) Are there any coops in a similar situation, and what have you done?
(2) What software / resources did you use for the generation facility studies?

I'm reluctant to volunteer until I understand the magnitude of the problem. I'm confident enough to do the distribution system. but the plants are a different matter. Thanks.

Jim Cross
Homer Electric Association
Kenai, Alaska

It's going to be quite an undertaking. For equipment i.e. switchgear etc., I think most people use commercial programs like EasyPower, ETAP etc. For overhead lines, people tend towards Arc Pro, or Duke Power also has a program.

jscross -
Having done studies at several generating facilities for a large power provider in the Tennessee Valley, I can say that they used power system software like K. Jackson mentioned above to model their generation facilities.

The software generally has no problem modeling the generators, and from their it looks similar to any other plant. It is important to get the generator information modeled correctly, and the external tie contributions should be included as well in order to get a full, accurate model. Many scenarios will need to be run, as well, due to the many sources, as well as the redundant power feeds necessary in a generation facility.

As having also done many studies, including utility systems (mostly smaller coops, muni's, IOU's) some of which did use Milsoft as the program for modeling the system for operations and engineering, they did not use that for arc flash analysis.

In all cases it was a combination of programs needed for the incident energy calculations. The program used by the utility to model the system was used to obtain the fault current, clearing time and X/R. ArcPro was used for open air faults and EasyPower was used for power plants, enclosed metalclad switchgear, etc.

Basically, the table in OSHA 1910.269 Appendix E provides the OSHA recommendations for methods to analyze the incident energy.

Please post the Milsoft response.