EMMC Value Drift

• To: tesla-at-pupman-dot-com
• Subject: EMMC Value Drift
• From: Terry Fritz <twftesla-at-uswest-dot-net>
• Date: Mon, 05 Jul 1999 19:46:15 -0600
• Approved: twftesla-at-uswest-dot-net
• Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

Hi All,

	I seem to be noticing a very slight capacitance value drift in my EMMC
cap.  It has 10 caps per string and has 5 strings of 1600 Volt 0.056uF
Panasonic high voltage pulse caps.  The total value has gone from 27.9nF to
27.7nF.  Each individual string seems to have drifted the same amount
(-0.7%).  This is close to the limits of my LCR meter but the drift seems
real.  After lasts week's run, it seemed to drop by about 0.3%.  I ran it
very hard this 4th and it seems to have drifted another 0.4% with that use.
 I run this 16000 volt cap at about 22000 volts so it is stressed in
voltage.  The strings seem to be fine current wise.  I wonder if the dv/dt
thing is degrading the internal connections??  Perhaps it will level out
with more use but it seems to be continuing in a linear way with the amount
of use.  If it continues, eventually it will fail and I can dissect the
remaining caps to see what the cause is.

Cheers,

	Terry

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