Abstract — This paper presents an interactive ATC calculation
program which is developed primarily as an educational tool.
The program runs under the graphical user interface of a previously developed software package, Power system Educational
Toolbox (PET) [1]. The user can choose multiple sources and
sinks as sellers and buyers for a power transaction. Repeated
power flow solutions are obtained and results displayed as the
user incrementally varies the transaction amount interactively.
Utilization of the program is illustrated using example cases.

[1] P. Krizan, F.H. Magnago and A. Abur, A Graphical Tool for the Analysis of Network Observability and State Estimation Algorithms, IEEE Power Engineering Society Winter Meeting, Vol. 1, 31 Jan.- 4 Feb. 1998, pp. 502 -507