Hi Jim:
IEC 60664-4, being a basic safety standard, has introduced
a number of new requirements that are particularly frustrating
for design and safety engineers of switching-mode power
supplies. Because it is a basic safety standard, we are
required to apply the requirements -- unless we can PROVE
that they do not apply to our equipment.
The new requirements are based on the research that is cited
in the bibliography. Most of the research was done by
electric power distribution researchers in Germany.
The principles are sound, but whether or not they apply to
the internally-generated high frequencies and non-linear
waveforms of a SMPS to the same extent as a power distribution
system is an open question. TC 109 believes they do.
I believe Lal Bahra will present a paper on this subject at
the PSES Symposium, October 22-23-24, in Austin, Texas.
Unfortunately, SMPS safety engineers are unable to garner the
resources to get academics to study and research SMPS insulations
as has been done by the power industry in Europe and Germany.
And, for good reason as we don't have systematic SMPS insulation
failures.
Best regards,
Rich
ps: TC22 PT5 should coordinate with TC108 HBSDT as we are
just completing our insulation requirements for the
new IEC 62368 safety standard. We should not have any
differences between our standards. If you contact me
off-line, I can put you in touch with the TC108 experts
applying the 664-4 requirements.
> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On Behalf
> Of Jim Eichner
> Sent: Monday, June 16, 2008 5:48 AM
> To: [email protected]
> Cc: Jim Eichner
> Subject: IEC/EN 60664-4 - Insulation Coordination for
> frequencies over 30kHz
>
>
> Does anybody have any background on what drove the writing of
> 60664-4? I am on TC22 PT5 writing a safety standard for power
> electronics, and we are wondering if the -4 requirements were
> driven by real-life issues (breakdown of clearances, tracking
> across creepage distances, etc.) with application of existing
> (ie 60664-1 based) requirements on higher frequency circuits?
> Or did this standard get written out of a theoretical basis,
> in the absence of real-life issues?
>
> If there is a track record of real-life issues, the follow-on
> question is whether those issues manifest in the lower
> frequencies of the broad range of 60664-4 (which goes from
> 30kHz to 10MHz), since power electronics would typically use
> only the low end of that range, up to perhaps 1MHz.
>
> Thanks in advance,
>
> Jim Eichner, P.Eng.
> Compliance Engineering Manager
> Xantrex Technology Inc.
> e-mail: [email protected]
> web: www.xantrex.com
>
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