How to size a circuit breaker for a panel?

Hi everyone,

My question is where can I find information about sizing a circuit breaker for a panel that includes a 3 phase, 250 HP DC drive, Plc, and other little components. This drive puts out 405 FLA,500VDC and draws from the AC supply about 340amps. The charts I've found for sizing the breaker covers are only for squirrel cage motors. Is there a good web site or book I can find this info? Also is there a formula for this, like 1.5 X FLA?

I would use just a disconnect and fuses for circuit protection but the customer demand a circuit breaker. Is it necessary to use it with a proper DC drive package?

Sorry my question may not be appropriate for this PLC forum, but with so many experienced control guys here hopefully can help shed some light to me. Maybe someone can direct me to a site for controls similar to this one. Thanks.

The National Electrical Code is the answer to your question for sizing CBs or any other electrical apparatus for that matter. Also, you might try this site http://www.patchn.com/forum/ for getting better response due to the topic you have. The above site is for Industrial Maintenance type questions and everything connected with it. There are some really good experts there as well. Hope this helps!

Thanks Randy.