12-07-2017, 12:02 PM
Halved or not? Good question!
If you apply 1mV AC to your series pair, of say 100uF each, it is inconceivable that the oxide film be wrecked by such a small inverse voltage. So, you'll see the pair behave as a single 50uF component.
If you raise the AC to 20V peak, then by equal voltage division, you'll get 10V across each capacitor. One of these will be the wrong way round, and 10V reverse is enough to upset things. So this capacitor would easily look leaky, and start clamping its voltage, leaving the majority of the volts across the other. So, the pair will behave like something between 50uF and 100uF.
What were your concerns about non-linearities, Jeffrey? :-)
True non-polarised electrolytics are deliberately formed with two equal foils (I don't know how!) so they never start passing any significant reverse current. Whereas, normal electrolytics have just one foil formed and the other has just a very thin oxide film on it (ideally there'd be nothing, but aluminium likes to cover itself with something), so has very little reverse withstand capability. Two of these in series therefore don't give much chance of behaving like a nice linear capacitor! But that's just my thoughts.
If you apply 1mV AC to your series pair, of say 100uF each, it is inconceivable that the oxide film be wrecked by such a small inverse voltage. So, you'll see the pair behave as a single 50uF component.
If you raise the AC to 20V peak, then by equal voltage division, you'll get 10V across each capacitor. One of these will be the wrong way round, and 10V reverse is enough to upset things. So this capacitor would easily look leaky, and start clamping its voltage, leaving the majority of the volts across the other. So, the pair will behave like something between 50uF and 100uF.
What were your concerns about non-linearities, Jeffrey? :-)
True non-polarised electrolytics are deliberately formed with two equal foils (I don't know how!) so they never start passing any significant reverse current. Whereas, normal electrolytics have just one foil formed and the other has just a very thin oxide film on it (ideally there'd be nothing, but aluminium likes to cover itself with something), so has very little reverse withstand capability. Two of these in series therefore don't give much chance of behaving like a nice linear capacitor! But that's just my thoughts.
