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Re: MMC Survivability

Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>


Although a lower voltage thing, the SISG pushes RMS currents to the 35 Arms region!! At that point, fully metalized MMCs become the dominate choice. Far higher capacitance but lower peak currents while still having considerable RMS current... The CD 940C20P47K-F at 451 amps peak at 13Arms is a choice. One needs to consider the caps at:


Easily available from rell.com or mouser.com... If you can handle the "tech", ScanTesla easily resolves the current details:




At 07:19 PM 8/29/2006, you wrote:
Hi Gerry,

Yes, it might be ok. But it is still riding the edge. Running the spice model would be ideal for the situation as this will at least give a model to go by (sure beats trial and error). When it comes to pigs in common STR mode, Cp is a good thing to spice up if one is thinking of using MMC's. The voltage capability of an MMC string becomes important as we near resonance, so the further we are away the better (in either direction). What is nice about high kva transformers is STR is still significant energy which helps the MMC compete with professional pulse caps in that range from a cost standpoint. However, to get a seriously robust MMC from a voltage standoff rating, pulse caps are a less expensive upfront cost (replacement cost is always on the side MMC's). I think for pig MMC's, we still need a larger value MMC cap to get the cost down. The 0.15uF's are just too low (I would really like to see a 0.5uF MMC available). 5kva is still in range of MMC's, so Jim just needs to decide what he is comfortable with.

Take care,