Rich,
Your comments raised several questions to me, but the most basic one
was - doesn't 4.4.5.1 still apply even if the power supply passes the
tests of 5.4.6 ?
Best Regards,
Kendall Wilcox
kwil...@fcpa.fujitsu.com
______________________________ Forward Header __________________________________
Subject: Re: Do UL1950 Recognized PS's Need Fire Enclosures
Author: Rich Nute <ri...@sdd.hp.com> at SMTP-MAIL
List-Post: emc-pstc@listserv.ieee.org
Date: 10/14/96 10:02 PM
Hello from San Diego:
At the urging of a colleague, I looked further into the question
raised by Mike Rains, whether or not a power supply needs to be
in a fire enclosure.
(I had stated that all primary circuits required a fire enclosure.)
In IEC 950 and its clones, Sub-clause 4.4.1 specifies two methods
for "achieving resistance to fire."
Method 1: Construction as specified in Sub-clause 4.4.2
and 4.4.3.
Method 2: Fault tests as specified in Sub-clause 5.4.6,
third dashed paragraph.
Sub-clause 5.4.6 first dashed paragraph requires fault tests in
any components in primary circuits -- REGARDLESS whether the
primary circuit is in a fire enclosure or not.
The third dashed paragraph implies tests in addition to the first
dashed paragraph, i.e., such as overload. Compliance with this
paragraph, in addition to the first dashed paragraph, qualifies a
circuit and its components for no fire enclosure.
So, the standard does not require a fire enclosure for a power
supply provided it is tested in accordance with BOTH first and
third dashed paragraphs of Sub-clause 5.4.6.
This is a different reasoning process than that of Mike Rains.
Best regards,
Rich
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Richard Nute Quality Department
Hewlett-Packard Company Product Regulations Group
San Diego Division (SDD) Tel : 619 655 3329
16399 West Bernardo Drive FAX : 619 655 4979
San Diego, California 92127 e-mail: ri...@sdd.hp.com
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