[AMPS] ripple current

Steve Thompson amps@txrx.demon.co.uk
Mon, 8 Mar 1999 08:10:57 +0000


In message <199903052149.QAA09127@pop.uky.edu>, William L. Fuqua III
<wlfuqu00@pop.uky.edu> writes
>
>   What is the actual RMS ripple current? According to a book I have it
>is 1.41 of dc output for a capacitive input filter, fullwave rectifier
>with an rectifier effeciency of 100 percent.
>   For a 1 amp plate current power supply the cheap ALL Electronics 
>capacitors should work just fine especially at 85 degrees c.
>
>73 
>Bill wa4lav
>
The rms and peak currents depend on the ratio of source and load
resistances and the capacitor value. For a decent high power PSU (bridge
with capacitor input) the ratio should be in the regions of 1-2% maximum
and you will have enough capacitance that it doesn't affect the
calculation). In these circumstances an old handbook I have puts the rms
ripple at about 3x dc current, and peak ripple at about 12x dc while a
spice simulation gives values of about 2x and 8x respectively.

Steve

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