Adrian! posted:FEM is usually about 1-2% accurate to real world. I'm using HFSS 14 for this.
Well, I looked at this, and then I look at that...
Adrian! posted:Okay guys. At AGHR (2700 ish ft) we got 74.8nF outside rail and 58.6nF center rail measured as is. Certainly more than the raw capacitance than I expected from the rail structure itself . I tried adding cap on the outside rail and DCS (about 13V excursion) is happy until we get to about 90nF .... so roughly 2:1 cap imbalance is where the problems seem to start.
I guess in the real world Finite element modeling has it's limitations.