Testing Old Cap, Vitamin Q with LCR meter.

[intravino]

I'm trying to test an old Spague Vitamin Q capacitor with a LCR meter.

It's a non polarized capacitor 0,27 uF, 1000 volts. It's used in an old trigger module from EG & G.

I have these readings with the LCR meter (GW-Instek LCR-916) :


Frequency           C (series)          ESR                  D

100Hz                256 pF              10 Ohms           0.002

120Hz                255 pF              13.7 Ohms        0.003

1 KHz                254 pF               2.05 Ohms        0.003

10 KHz              253 pF               0.37 Ohms        0.006

100 KHz            250 pF               0.12 Ohms        0.019



Can you please tell me if the cap is still good?


It's the first time that I'm using a LCR meter. I'm tempted to say that the cap is still good but I need a second opinion.



Thanks,


Intravino

[richard.cs]

Either you've made a typo or the capacitor is bad, I'm inclined towards the former. 0.27 uF is 270000 pF. Are you sure it's not a 0.27 nF capacitor? Is the meter definately reading in pF?

[intravino]

Yes, sorry about this.

The cap is 0.27 uF.

All of the reading are in nF not in pF.

[N2IXK]

Capacitance looks good, but modern testers don't apply anywhere near enough voltage to give a meaningful leakage test on a 1kV rated capacitor.

[T3sl4co1l]

Capacitance looks good, but modern testers don't apply anywhere near enough voltage to give a meaningful leakage test on a 1kV rated capacitor.

^^ You need a hipot and leakage test (or megger, same idea) to really tell if it's bad.

Wax caps are almost always poor resistors, but film caps usually keep okay as far as leakage.

Tim