Hi Peter:
As a general rule, the insulation on the outside of
an electrolytic capacitor is considered functional
insulation. (Indeed, the insulation between the
elements of the capacitor and the aluminum can is
clearly functional insulation.)
As far as I know, only X- and Y-capacitor insulation
may be considered Basic insulation (in accordance
with IEC 60384-14).
Consequently, the insulation on the capacitor must
be ignored. The distance between the capacitor
case and grounded metal must meet the creepage and
clearance distance requirements, or solid insulation
must be interposed between the capacitor and the
grounded metal.
The fact that some certified power supplies do not
meet the spacing requirements is not an argument
that such spacings are not required. This simply
means that neither the power supply safety engineer
nor the certification engineer caught the problem.
After all, the spacings within a power supply
comprise a rather difficult and tedious job of
identifying the various voltages and corresponding
creepage and clearances on the PWB two-dimensional
plane. Often, we don't look at the clearances in
the third, vertical dimension.
Best regards,
Rich
-------------------------------------------
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.
Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/
To cancel your subscription, send mail to:
[email protected]
with the single line:
unsubscribe emc-pstc
For help, send mail to the list administrators:
Michael Garretson: [email protected]
Dave Heald [email protected]
For policy questions, send mail to:
Richard Nute: [email protected]
Jim Bacher: [email protected]
All emc-pstc postings are archived and searchable on the web at:
No longer online until our new server is brought online and the old
messages are imported into the new server.
