Recloser Curve Equation 1

[mgtrp]

Does anyone have an equation that approximates the old Cooper recloser curve 142?

Thanks.

 

[wareagle]

http://www05.abb.com/global/scot/sc...56c44005e98c4/$File/PCD Protection Curves.pdf

 

[mgtrp]

Thanks, but that just list curve 142 as "point to point data" rather than giving equation parameters like most of the other curves.

 

[DTR2011]

I have researched this extensively. There are no true "equations", on reverse engineered best fits. You may want to check out the Basler web site, as they have some excel sheets that do a nice comparison of the real curves and best fit equations.

 

[MaxPovver]

Has anyone tried to get them from Cooper?

 

[mgtrp]

Thanks smallgreek, I found exactly what I was after on the Basler website.

 

[davidbeach]

The curves on the Basler web site were hand tweaked to provide a best match against a digitized version of the Cooper curves. Some of them turned out very well, others not so well. There were also 2 or 3 of the Cooper curves that (looking from the upper right of the sheet) were convex for lower currents and then concave for the higher currents; there was no way have having a relay curve emulate that convex portion, so the curve emulates only the concave portion and includes information as to a multiplier for the pickup. An interesting little project putting it all together, though.

 

[dpc]

So Cooper develops analog electronic curves to match the old hydraulic reclosers curves, then migrates this to digital recloser controls and now we attempt to curve-fit these into a linear equation. That's progress.