Calculating ripple current in a capacitor

briankj

Joined Sep 21, 2018
5
It’s been a lot of years since college but I believe you can calculate you ripple like this.
You got 240VAC and I assume 60 hz, from a full wave bridge. Your cap is going to charge to 340vdc with the pulses coming in at 120hz. In between those peaks you are draining the cap at 50amp which is 50 coulombs/sec. So in the 0.0083 seconds (1/120) you will have drained off 0.4166 coulombs of charge. Now a 18000uf capacitor will give you 0.018 coulombs per volt so dividing 0.4166 by 0.018 = 23.144 volts which is what’s draining off between charges i.e. ripple.
 
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