Mathematics Equations for S&C Power Fuses and electromechanical relays 3

[ingahs]

Hi Everyone

I need to know where can I find the equations curves for S&C Power Fuses and for electromechanical relays such as;
CO-11
CO-7
IAC ect...

Thanks-Alexis

 

[davidbeach]

S&C has, in the past, made available a program that will print out a set of times/currents for all of their fuse curves. I haven't had a need for it for quite some time, and don't recall off hand where my copy might be, I don't know if they still provide it, contact you local S&C person. No equations for the electromechanical relays. For best results get a good clean copy of the TCC and digitize it. Digitize the values using the exponent of the log decade (10A = 1, 100s = 2, etc.) and then dump that into an excel file and raise 10 to each value to get the actual plotted point.

 

[dpc]

http://www.sandc.com/support/tccs_main.asp

Fuse data can be found at link above.

I think there actually may be equations for the IAC relays but I don't feel like looking for them. You be better off and more accurate to do what David Beach suggested anyway.

 

[dpc]

I remembered where I saw the IAC equations -

Go to GE website and download an instruction manual for UR series relay, such as the T60. In the manual, they have equations for the IAC, IEC, and IEEE curves. At in the version I'm looking at they do. Probably also in the older SR-760 and similar manuals as well.

 

[davidbeach]

I haven't looked at the IAC equations dpc mentioned, but as I understand they will be a curve fit at best. They may be a very good curve fit, but the published TCCs were always based on testing the relay at multiple points and plotting the curve between those points.

 

[unclebob]

http://download.merlingerin.com/C12...1B18BC12570490025D3C6/$File/pcred301005fr.pdf

This is a large document. Look at pages 60-65 for some formulas.

 

[Eleceng01]

I agree with davidbeach, it has always been my understanding that the ols electromechanical relays did not follow the IAC, IEC equations exactly so using the formulas could get you into trouble in real applications.