leakage of caps...

[Roel Das]

Does anyone have an idea of how to estimate the leakage of caps?
The cap value is 22nF, metalized polycarbonate film (400V DC cap).
Applied voltage: DC,  10V maximum...

I've been calculating this with tangent delta (tgd)...
Is what I'm doing right?

tgd = Ir / Ic

with Ir and Ic the currents in the R and C of the equivalent circuit of a
practical capacitor.

with
Ir=U/R
Ic=1/jwC

this gives: tgd = 1/wRC

tgd for metalized polycarbonate film caps is (lower than) 30 *10^-4 at 1
KHz.

Solving the equation for R, and using these values gives:

R = 1 / 30 * 10^-4 * 2pi * 10^3 * 22 * 10^-9 = 2,4 MOhm

This is the what my teacher told me. Is this be right? Seems quite a low
resistance...

Lower on the page of the caps databook it says:
R between leads, for C <= 0.33µF :     >30000 MOhm

This value suits me alot better. But is this the one to use?

Any experts on this?

Thanks
Roel