Hello!
I was wondering if anyone could answer a question I have. SKM default values, how accurate are they? If I have an ARC flash curve, the Td" and Td' values are defaults. If my trip happens somewhere in between those values, which would be more accurate? Using the exact trip value or the default values? Any insight at all would be extremely helpful.

I'm not sure what you mean by "an ARC flash curve". Please elaborate.

I guess this is related to your June 21 post with attached graph. I have no idea what the attached graph represents. It seems to be a combination of a current sine wave and a generator impedance decrement curve or something. Please explain.

You should keep your posts on a single subject in one thread.

For the graph, the second half is a TCC curve. I'm mostly just wondering if it would be more accurate in my calculations to use the defaulted trip time SKM gives you, or use the trip time you know to be true, since I've seen them be different numbers

The two Td points on either side of the trip point are what appears to be the relative clearing times for the change in reactance for the generator/system while transitioning from the sub-transient to transient and ultimately to the steady state impedance of the machines. Using the sub-transient offers the maximum fault current based on the impedance models with the decaying time constant (X/R etc.). The trip time is nearer to reality in that the combined time for OCPD + Breaker clearing time is well beyond the Td".