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ceramic capacitor voltage

Hello all,

this might be a bit off topic, however is there a (easy or not) way to tell the working voltage of a ceramic disc capacitor? I have tons of these surplus or saved capacitors but often the working voltage is marked when equal or higher than 1 kV. When I have to reuse a capacitor in a high but not so high voltage circuit (let's say 200 Vdc) I never know how to find the correct size or how to measure the insulation voltage of the capacitor. Fortunately film capacitor have a clear marking :-) Best regards

Francesco IS0FKQ

Reply to
francesco.messineo
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Francesco-

A problem with determining a capacitor's voltage, is that the test can be destructive. Once the insulation resistance has broken down, the capacitor is most likely no longer unusable.

For ceramic capacitors, you can take a chance and apply twice the expected working voltage and verify there is no leakage after the initial charging has occurred. Some capacitor testers have a capability to do this test.

Fred K4DII

Reply to
Fred McKenzie

Dielectric stress tests should be run for a long period of time, if you really want to be sure.

If the OP has lots of capacitors and the ability to safely test at high voltages, then destructive testing is an option. One determines the failure voltage and then extrapolates the safe working voltage from that (more than one unit must be failed, to be reasonably sure).

High-capacity ceramics might be safe at 50 dcwv, or so. Moderate capacity ceramics are probably OK at 100 to 200.

Reply to
Charles Schuler

my first q is to check that youre familiar with the voltage codes used on ceramics. V rating is indicated by one letter or number. If so, and theyre unmarked for some reason, do you have many of each type? If so, testing a few to destruction would be a workable way to get some ratings. Cant think of any other options, unless perchance you remember the operating V of what they were taken off.

NT

Reply to
meow2222

snipped-for-privacy@care2.com ha scritto:

I'm not sure about these codes, often on ceramics I see only 3 numbers and one letter and I assume the one letter is the tolerance code (M, Z often). Other have someting like 103P with an E on top and 82 lower in the disc. Others have YY on top and usual capacity code on a lower line. In short the answer is no, I haven't been able to find good references about all markings, so if anyone has good sources for learning these codes please share them! As for the destructive test, yes, it's an option, so if other else fails, I'll test them this way.

Thanks!

Francesco IS0FKQ

Reply to
francesco.messineo

Capacitor Voltage Rating codes:

1 =3D 100V 3 =3D 25V 4 =3D 4v 5 =3D 50V 6 =3D 6.3V 8 =3D 400V 9 =3D 5v /=3D 10 pF) J =3D =B15% K =3D =B110% M =3D =B120% Z =3D +80%, -20% P =3D +100%, -0%

NT

Reply to
meow2222

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