Raymond,
The standards (e.g. IEC 60950 section 5.3.2) allow production hi-pot
testing to be reduced to 1 sec., but does not address any change in
voltage, up or down. It usually takes more than 1 sec. for a hi-pot
to ramp up, stabilize, then ramp down. We used to use about 3 secs
to ensure at least 1 sec of full hi-pot voltage.
We have usually elevated our production hi-pot voltages for several
reasons:
- reduced test time
- power line variations affecting hi-pot output
- hi-pot calibration variances
- etc.
For example, we would use 1750Vac with an arc detect option for
the specified 1500V test, and 3750Vac with arc detect for the
specified 3000V test. Sometimes we ran all units at the higher
3750Vac to avoid changing hi-pot settings and introducing errors.
Most well designed ITE will easily pass a 3750Vac hipot without
damaging or weakening internal insulation. If the insulation is
damaged by such values, then it is unlikely it would survive a
single lightning strike surge, often well above 3750V.
George Alspaugh
raymond.li%[email protected] on 08/22/2001 10:25:43 AM
Please respond to raymond.li%[email protected]
To: emc-pstc%[email protected]
cc: owner-emc-pstc%[email protected] (bcc: George
Alspaugh/Lex/Lexmark)
Subject: Re: Manufacturing Hipot Testing
Dear All,
I have read one BSEN standard suggesting not to perform hipot testing at
the test voltage, 3kV, 1.25kV or 3.75kV in mass production. The reason is
that it might introduce potential failure in future operation by the
customer not immediate failure. It also suggests if hipot testing is done
on production line, lower testing voltage, i.e., 1/2 of test voltage should
be applied. I would like to have comments on this concern while doing
hipot test on production line or other modern way to replace the hipot test
on production line.
Thanks and regards,
..
Raymond Li
Omni Source Asia Ltd.
---------------------------------------------------------------------
Phone: +852-2542 5303
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John Woodgate
<[email protected]> To:
[email protected]
Sent by: cc:
owner-emc-pstc@majordom Subject: Re:
Manufacturing Hipot Testing
o.ieee.org
22/08/01 01:39 a
Please respond to John
Woodgate
I read in !emc-pstc that Doug McKean <[email protected]> wrote (in
<[email protected]>) about 'Manufacturing
Hipot Testing', on Tue, 21 Aug 2001:
>IMHO, if I were to address the initial question regarding
>manufactoring
>testing of a product bound for Europe - unless there were some severe
>national deviation differences from a similar type of US domestic
>approval
>of the product, I'd continue along with hi-pot testing just as if the
>product
>were bound for a domestic (US) market.
Well, you have come to the right conclusion but for two wrong reasons.
In Europe, there are no longer any 'national approvals' like the old
SEMKO etc. There is ONLY the Low Voltage Directive, and the European
Standards (ENs) that have been 'notified' in the Official Journal as
providing evidence of compliance.
However, most if not all of these ENs have *mandatory requirements* for
100% production-line testing (confusingly called 'routine testing'),
including a 'hi-pot' test.
It is entirely the responsibility of the manufacturer to ensure that the
Declaration of Conformity for the product is true, and to do that he
MAY, but does not have to, employ a test-house to produce a report and
maybe an expensive certificate and grant permission, in return for more
money, to apply a glamorous sticker to the product.
--
Regards, John Woodgate, OOO - Own Opinions Only.
http://www.jmwa.demon.co.uk
Eat mink and be dreary!
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