I am in need of some high-ripple-current caps for a power supply that I am building. According to my sims, at full power the PEAK ripple current will be about 12A or so. I will probably get some NOS units from Ebay. I am currently considering a couple options and I am trying to figure out the plusses and minuses of each.
Cap A:
6300uF @ 400V rated
Cornell Dubilier DCMC series, can size code DF, 3" x 5.625"
Cap B:
4500uF @ 250V rated
BC Capacitor 3188 series, can size code GH, 3" x 5.625"
Both caps are computer grade type, with screw terminals. The can size is the same for both. I can get datasheets on the product series from each manufacturer, but the exact product (rated V and Aripple) is not listed. I know that these are genuine, and both are manufactured in 2001. Both are being sold for about the same price.
I have tried to interpolate the datasheets to guesstimate the actual ripple current rating for the specific model in question, but it's a little murky. The closest 3188 cap that is 250V rated has a can size of 2"x4.625", which is much smaller and Aripple is 9A. A 250V 15,000uF cap that has the GH code has Aripple = 14A. For the BC caps, the closest part in the datasheet is a 6000uF 400V part with a similar case (code DE, 3"x5.125") rated at 13A. This seems to tell me that the 3"x5.625" can size for either of these would be rated for at least 14A, possibly more for the 250V rated cap.
Does that sound reasonable? Any thoughts about these options? Should I just go with Cap B, since it has a larger capacitance by about 35%?
Cap A:
6300uF @ 400V rated
Cornell Dubilier DCMC series, can size code DF, 3" x 5.625"
Cap B:
4500uF @ 250V rated
BC Capacitor 3188 series, can size code GH, 3" x 5.625"
Both caps are computer grade type, with screw terminals. The can size is the same for both. I can get datasheets on the product series from each manufacturer, but the exact product (rated V and Aripple) is not listed. I know that these are genuine, and both are manufactured in 2001. Both are being sold for about the same price.
I have tried to interpolate the datasheets to guesstimate the actual ripple current rating for the specific model in question, but it's a little murky. The closest 3188 cap that is 250V rated has a can size of 2"x4.625", which is much smaller and Aripple is 9A. A 250V 15,000uF cap that has the GH code has Aripple = 14A. For the BC caps, the closest part in the datasheet is a 6000uF 400V part with a similar case (code DE, 3"x5.125") rated at 13A. This seems to tell me that the 3"x5.625" can size for either of these would be rated for at least 14A, possibly more for the 250V rated cap.
Does that sound reasonable? Any thoughts about these options? Should I just go with Cap B, since it has a larger capacitance by about 35%?
More details on what you are building? Do you need high voltage caps? The voltage ripple with 12A peak draw on a lowly 6300uF is going to be pretty high.
This is for my variation on a capacitance multiplier power supply with over-voltage protection. Details are in that thread:
http://www.diyaudio.com/forums/powe...tance-multiplier-over-voltage-protection.html
In short, the rails are +/-86V. If I simulate a 600W output by the PS, the ripple on the first set of caps is about 12A peak. I assume that the cap ripple value is RMS and I wouldn't be drawing full power any more than a fraction of the time, if at all, but I did find these caps that are rated to cover even the peak current draw. I am trying to clear up the specs, since I can't get exact ones for the parts available for sale.
http://www.diyaudio.com/forums/powe...tance-multiplier-over-voltage-protection.html
In short, the rails are +/-86V. If I simulate a 600W output by the PS, the ripple on the first set of caps is about 12A peak. I assume that the cap ripple value is RMS and I wouldn't be drawing full power any more than a fraction of the time, if at all, but I did find these caps that are rated to cover even the peak current draw. I am trying to clear up the specs, since I can't get exact ones for the parts available for sale.
The rating that you need to worry for capacitor life about is RMS ripple current. The only thing you need to worry about with the peak value of the ripple current is if the [peak ripple current X (ESR + parasitics)] + droop violates your ripple voltage requirements.
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