18(Houston/Secr.)27
IEC/TC 18 Plenary meeting
In Houston 1998-10-14/16
Annex C uses the results of Annex B to complete a full time dependent system calculation. The Annex follows the guidelines of IEC 61363-1 clause 8.7. The first part of the Annex defines the system and calculation requirements and completes a "manual" approximate calculation. The second part of the Annex calculates the complete time dependent short-circuit current at specific points on an electrical system. This Annex is 75% complete. The work outstanding involves completing the time dependent calculation and linking the word document to the Excel spreadsheet to enable an interactive calculation to be completed.
Annex D applies specific approximations to the calculation to demonstrate their effect on the final result.
The work has attempted to provide not only a documented calculation illustrating the IEC 61363-1 formulae but also to provide an interactive computerized calculation. The calculation is done with Microsoft Excel and the documentation is completed in Microsoft Word. The system data is first entered into the Word document. This data is then linked to the Excel spreadsheet and calculations completed using IEC 61363-1 formulae. The calculation results are then linked back into tables in the Word document which illustrate the calculation steps and list the results.
The major problem encountered has been to successfully link data between the Word document and the Excel spreadsheet. Although the linking works successfully for small documents, problems have been encountered with the number of links required by this work. Initially it was hoped that complete tables could be linked as single entities however following several major formatting catastrophes, and acting on the advice of Lloyd' s Register of Shipping computer experts, it has been found necessary to link each individual cell within a table. This takes a considerable amount of time!
Work is progressing and it is intended to issue discussion documentation in the near future. The documentation will be issued even if the entire computer linking is not complete. Because of formatting problems, these documents will be issued as soon as the linking for Annex B is complete. At the same time I hope, as a minimum, to issue the narrative for Annex C.
Annex D will not be available for at least 6 months. The final work will be issued either on standard diskettes or as a read only CD.
