Selective Coordination Tools and Spreadsheets - Part Two

[ali hassan]

In the prevouis Topic "Selective Coordination Tools and Spreadsheets -
Part One", I showed that our study for selective Coordination will be
based on the following main parts:

Part One: What is selective coordination?

Part Two: NEC code and Selective Coordination

Part Three: Method of performing a selectivity coordination study
First: By using Selective Coordination Time - Current Curves
Second: By using Selective Coordination Charts/Tables.
Third: By using Siemens calculators / spreadsheets.

in this previous Topic, we covered part one, part two and the first
method of performing a selectivity coordination study By using
Selective Coordination Time - Current Curves.

today, I will continue explaining other Methods of performing a
selectivity coordination study as follows:


Second: Selective Coordination Charts:
Charts are available which list, in varying styles, breakers that
selectively coordinate with other breakers at specific available fault
current levels. An advantage of the charts is that they are often more
accurate than curve comparisons as they are based on more specific
test data derived for selective coordination. If there is disagreement
between overlaid curves and charts, the chart data should be used.

The following steps will assure the best use of the Selective Trip
Coordination Table:
1. Conduct a short circuit study to determine the available fault
current values at each level of the system where coordination is
critical by using the Estimated Available Fault Current Calculator or
any other Tool/Software.


to read more, please follow the below link:

http://alihassanelashmawy.blogspot.com/2012/01/selective-coordination-tools-and_19.html