Electrical – How to verify capacitor voltage rating?

capacitor

Ceramic capacitors are not marked with any kind of code that we can identify their model. Think that we have a batch of capacitors (lots of nearly identical capacitors) with unknown ratings. We can obviously use LRC meter to measure a capacitor's capacity. How can we verify or identify its voltage rating?

One solution I can think of is applying the alleged voltage or each possible voltages for ceramic capacitors in the market for a given(?) period of time, then measure its capacity again. If capacity is decreased, we can defer that the capacitor is burned and the capacitor's voltage rating is the voltage that we applied before last one.

Is there any better solution for that? If not, how much time is enough for a reliable voltage rating testing?

Best Answer

The voltage rating is tied up to the lifetime of the capacitor, so doing a short test will not give definitive answers immediately, which is unfortunate for you.

However I would play with the DC-bias characteristic. When applying a DC voltage across the capacitor to capacitance value will drop significantly. Especially DC-bias close to the voltage rating.

I recommend that you look at Murata's SimSurf online portal. Here you can input a DC-bias for a given capacitor and see how much the capacitance drops. Then try and compare with your test values, from DC Power supply and LCR-meter.