I was curious to see how many people that using EasyPower are using the Integrated method for finding the AFH when there are multiple sources. Per EasyPower, "this method takes into account the decreasing currents from motors and generators and also from multiple sources being switched out through protective devices tripping. The integrated method is the closest to a realistic scenario."

I have used it in the past and it does make a huge difference and model what is more realistic in the field. One of the nice things that it does as well, is it allows motor contribution to decay, depending on the facility you can have some large motor currents contributing. Also it keeps calculating at set intervals so when sources drop out that contribution is no longer being factored in. Typically the calculations use maximum magnitude fault for the longest duration of the last source clearing.

This is one of those areas where motor contribution modeling was not well defined in IEEE 1584. Until what I would consider this more realistic model was developed, motor contribution was a bit ackward. If you include it, often it would appear as sustained which is not correct and could effect the incdent energy. I would often try modeling incremental percentages of motor contribution just to see what happened.

I talked directly with EasyPower about their model several months ago. They explained the decay method they are using which I thought was quite good. They take the more realistic approach of the dynamic nature of the decay so the initial event (t=0) has all of the motor contribution then it decays over several cycles.

Yes. Great software at least for me.