What you want to do requires some study, time/current curves for every fuse or breaker you're dealing with, and log-log graph paper. Fuses and many breakers aren't adjustable. Long time, short time, and instantaneous trip settings work together to create a taylored, adjustable time/current curve. If co-ordinated, you should be able to plot the curves of the various fuses and breakers, without the curves intersecting. The curves might get close in places, but crossing is not a good sign. That indicates a time and current combination which might cause an upstream breaker to trip first or concurrently. But even if you put your thinking cap on and soak it all in, you still need an appropriate test set to verify trip unit dial settings.
Joe
