>
> Looking at Jenning's data on Vacuum Variable capacitors I noticed that
>the
>voltage rating on the capacitor is the Test Voltage and the working voltage
>is less.
>For example a 3000volt cap Cxxx-300-3 has a test peak voltage rating of
>3Kv and a working peak voltage rating
>of 1.8KV. A 5Kv one has working voltage of 3KV and a 7.5 has working peak
>voltage of 5KV.
> So if I am running a 4-1000A with 5K plate resistance and 1500 watts out
>the RMS Plate voltage would be 2740 Vrms or 3872V peak. I can't use a
>3000V cap based on those
>figures but must use at least a 7.5KV cap.
> So what gives. I expect most of us are pushing these caps beyond their
>working voltage limits.
>
? DC is normally used to test vacuum caps. Withstanding (breakdown)
potential decreases as freq. increases. At 30MHz, a 60% derating is
commonly used.
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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