For the major types of filters the secondary RMS current is related to
the DC load current as:
Inductor input: 0.7
FWCT capacitor input: 1.0 to 1.2
FWB capacitor input: 1.6 to 1.8
Data from O.H. Schrade: "Analysis of Rectifier Operation"
Tomm
Steve Thompson wrote:
>TexasRF@aol.com wrote:
>
>
>>
>>I don't have the answer Bill but there is this to consider:
>>
>>In the capacitor filter, current only flows about 20% of the cycle. This is
>>very much not a sine wave and I wonder how rms even applies in this case.
>>There has to be some terrific harmonics in that waveform!
>>
>>
>rms applies to any waveform - if the voltage/current are sinusoidal,
>then the 1.414 or .7071 factors apply. Where the waveform is a series of
>short peaks, then there isn't a simple numerical factor to use - the rms
>value has to be calculated by looking at data points over a time period,
>or measured using something that does the equivalent electronically.
>
>Your example of 5x the current for 1/5th the time leading to 5x the heat
>is a much better way of getting the point across!
>
>Steve
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