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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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In Reply to: Re: black gates in parallel posted by Robert Karl Stonjek on December 21, 2001 at 23:52:45:
Robert S. I am not going to go back to completely understand your original question, but this is how I look at things. First, there is the original input surge current to charge the cap. This can in fact be 100 or more amps, IF you do NOT use a transformer and have a large enough cap. In the old days, 20+ years ago, we would insert a power resistor in front of the cap and short the resistor out with a relay, after the cap is charged. Today, we use heat sensitive 'surgistors' to limit the original charge current, and only on our best designs, do we use a shorting relay like we did in the old days. Of course, any transformer will limit the peak current, both with its winding resistance and core saturation.
Of course, once the cap is charged up, then the cap doesn't have to conduct so strongly, unless you are shorting out the cap, once it is charged up. This could happen with a flashlamp load, but I doubt that an amp would be so difficult. The exact charge current through the caps, after first charge, is difficult to predict, but it could be measured easily enough by putting in a current sensing resistor (.01) ohms or so in series with the ground leg of the cap, and measuring it with a scope. I doubt that you will see too many amps, and they will be only there for a short part of the AC cycle, so even though the I(squared) R losses could be significant, at least the cap can rest for most of the cycle.
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Follow Ups
- Re: black gates in parallel - john curl 12/22/0115:46:20 12/22/01 (5)
- Re: black gates in parallel - Robert Karl Stonjek 17:34:22 12/22/01 (4)
- Re: black gates in parallel - john curl 20:27:42 12/22/01 (3)
- Re: black gates in parallel - Robert Karl Stonjek 13:54:04 12/23/01 (2)
- Re: black gates in parallel - john curl 15:31:52 12/23/01 (1)
- Re: black gates in parallel - Robert Karl Stonjek 16:18:41 12/23/01 (0)