Capacitors: ripple current vs maximum current capability for one discharge

Thread Starter

matters_100

Joined Mar 30, 2016
18
Hi,

For an electrolytic capacitor, is there an empirical relation between ripple current and the maximum yet safe current which can be drawn for dozens of miliseconds for a discharge application ? I mean without damaging the capacitor.
For example, if an electrolytic capacitor is rated for 30A ripple current at 120Hz/85°C, how much current can I continuously draw safely for 100ms ?
I suppose the limiting factors would be the heat generated and the connectors maximum current capability.

Thks
 

Picbuster

Joined Dec 2, 2013
1,008
The delta voltage = (current x discharge time cap )/ capacitor
discharge time related to impedance from load.
delta voltage= top top value ripple
current draw from cap up its maximum stored energy (no coil in load).
 

Thread Starter

matters_100

Joined Mar 30, 2016
18
I guess I haven't expressed myself clearly.

For example, if I have an application which requires 500A for 100ms only once every minute (assuming a capacitance large enough), would a low ESR electrolytic capacitor rated for 30A ripple current at 120Hz/85°C be able to handle the large current without damage ?

Thks
 

wayneh

Joined Sep 9, 2010
16,398
Have you looked closely at the capacitor specifications? I seem to recall seeing information like that - peak "instantaneous" current. I would think the manufacturers are the only ones likely to be able to answer your question.

I believe - but don't know - that capacitors can survive intermittent shorts. Stuff outside the capacitor lights up and vaporizes, but I think the capacitor is OK.
 
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