application (specific) of polar and non polar capacitor

reza6430

Dear all,
As we know, there are two kind of capacitor polar and non polar. From that, I still did not know yet about specific application of them.
Can give me something a clear of explanation of that?

thank you
reza_diharja

Windadct

Typically "polar" or polarized caps, are electrolytics - they requuire the voltage across them to always be positive ( in relation to their polarization) - often used when Large capacitance are needed and are typically lower cost (per farad) than other non-polarized types. Think a filter for a DC power supply - the Voltage across the Cap is always the same polarity - however it does see ripple - or AC current.

Non polarized there are many types from signal to power applications - but technically they do not have the same requirement that the applied voltage always be Positive.
I know the Power caps off the top of my head as comparison:

These two caps are about the same physical size and we use both as a DC Bus Capacitor in Power Electronics
Electrolytic 3900uf / 500VDC : Lower cost, more bulk energy storage, lower voltage ( we often use in series to get higher bus V - which halves the capacitance), shorter life.

Film Cap 420uf / 1100V (AC or DC) :Higher cost, lower energy BUT typically LOWER Series Resistance and therefore a higher Ripple Current allowed, longer life etc.

Most of our customer spec the Film Cap.

yungman

You can get higher value polarized cap cheaper and smaller. But polarized cap cannot match the frequency performance of the non polarized cap. Mainly you use polarized cap with high value of above 4.7uF. For lower value below 1uF, there is no reason to use a polarized cap.

Application wise, it is too broad to say. Usually, people tends to use polarized cap for power supply filtering as you can get high value in smaller size and cheaper. But this is such a general statement as people use polarized cap for DC blocking in signal path also.

reza6430

Hmm, may I think it is dependent of frequency to use