400 cycle busbars

Do you have a specific temp rise you are trying to optimize around?

...I assume you are looking for a 'no airflow' continuous rating.

If I remember 300 Hertz has a greater Skin Effect than lower frequencies.

Your Buss Bars can be reduced in size than those carrying lower frequencies.

Gotta be a formulae around here some where?

Sorry, but reducing the SIZE is not completely correct. To lower the skin effect the THICKNESS has to be smaller but the current carrying area = SIZE has to be the same to avoid overheating, so only the SHAPE has to be changed.

Busbars of 600mm² are good for 1000A up to 70°C.
Regards Uwe

My goal is to find or develop a table of continuous busbar Ampacitys for various copper busbar sizes allowing for 60, 75 and 90 degree C maximum temperatures with no forced air flow.

As for Temp Rise, you can calculate that pretty closely using the following equation: Trise('C)=(Power Loss (watts)/Surface Area)^.833 Power Loss (watts)=I^2*R (Current Squared in Amps* Resistance in Ohms) while Surface Area is the sum of all 4 sides in square mm in the above equation.

As for your resistance, you will have to determine the material used (such as straight copper) it's resistivity per unit area, your total area and actual length.

Skin Depth for 400Hz begins around .14185 inches or can be computed by: 2.837/SQRT(frequency in Hz) So as long as you keep your bus bar thickness below .14185" you will have no skin effect to be concerned about.

Or if you really want to get into it:

http://en.wikipedia.org/wiki/Skin_effect