Westinghouse CO-8 curve information

[cgingras]

I am trying to find the equation used to calculate the time current characteristic curve for a Westinghouse CO-8 induction disk relay. I have the curves originally published by Westinghouse but i need to enter information into coordination software for a point in between time dials. So if someone has the equation or can point me in the right direction i would appreciate it.

 

[jghrist]

See thread238-102121

 

[dpc]

Your software should really incorporate a curve-fitting routine that will allow you to enter curves via a listing of points. There will be a lot of curves that will not have a published mathematical expression.

Most commercial coordination software provides this capability.