At 03:32 PM 2/4/00 -0800, Steve Thompson wrote:
>Can't claim practical experience, but I did run a Spice simulation. I
>assumed the primary R effect doubled the secondary Rs, and I assumed about
>4.5kV dc (didn't keep a copy of your original post).
>
>At .75A dc in the load, the current in the diodes is 6.5A peak. At 2A dc,
>the diode current is 12A peak, with a longer conduction period. This is 40ms
>after 'turn on', when the current appears to have settled to a constant
>value.
>
>Steve
Steve, thanks for the Spice run. Very interesting.
My actual output voltage at key down was 3100, key up (ZSAC) was about
3400. Using the graphs, I had estimated about 2.9 amps RMS current. But
what does that really mean in this context. I know we can calculate the
peak diode current, but few, if any, rectifier diodes have a REPETITIVE
PEAK CURRENT spec. So what's a guy to do?
I can see a trend here. It's becoming apparent that 6 amp diodes in the
scenario under discussion will barely provide sufficient safety margin to
allow for variations in parts and design assumptions.
73,
Larry - W7IUV
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