Hi, Ned
What you've stated below is a misapplication of the
standard. ยง4.5.1 (you quote from 60950/60950-1) is related
to normal operating condition testing, rather than the
abnormal operating condition of ventilation opening
blockage. I also doubt that instructions will include
starving of
In my experience UL always required to block one side at a time, and offered
to try to shorten the test time by blocking all. Not a requirement by any
means.
Leo Simon
Consulting Compliance Engineer
EMC Corporation
80 South St.
Hopkinton, MA 01748
Tel 508-249-5022
Fax 508-249-5500
From:
: Stone, Richard [mailto:rst...@xl.com]
Sent: Tuesday, November 25, 2003 10:28 AM
To: Brian O'Connell; emc-p...@majordomo.ieee.org
Subject: RE: Blocked ventillation testing
could this be in susbstitution for complete 100% fantray failure?
I dont think its vaild, as youd still have openings
Having worked at UL for many years in ITE, and having been the UL seminar
leader for ITE for several years, blocking vents during on one side only was
always the rule/what we taught = one fault at a time. Of course the years
have been adding on since my days at UL so things may have changed. I
.
If it is not rack mounted, then they are over testing.
Ned Devine
Entela Inc
From: Peter L. Tarver [mailto:peter.tar...@sanmina-sci.com]
Sent: Tuesday, November 25, 2003 12:32 PM
To: PSTC
Cc: Robert Johnson
Subject: RE: Blocked ventillation testing
Bob -
You're quite right that the proposed
...@majordomo.ieee.org
[mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Brian O'Connell
Sent: Tuesday, November 25, 2003 12:28 PM
To: emc-p...@majordomo.ieee.org
Subject: RE: Blocked ventillation testing
At least for 60950-1, this should be considered a multiple fault; unless the
intended end-use
One fault at a time. You can choose, your decision not theirs, to block all
at once to save time. (Make them show you how much they are going to reduce
the test cost with this streamlined testing
Gary
From: Robert Johnson [mailto:robe...@rcn.com]
Sent: Tuesday, November 25, 2003 7:56 AM
To:
Bob -
You're quite right that the proposed test constitutes a
multiple fault condition and is not supported by any UL
standard that I am aware of. I have never had any agency
request blocking of all equipment ventilation openings. UL
HK should provide you with a rationale for this testing and
At least for 60950-1, this should be considered a multiple fault; unless the
intended end-use installation indicates a mechanical situation where all
vents blocked could be considered a SFC.
I am not aware of any National Differences that would allow this test
condition. If UL is acting as an
Bob,
UL 60950 1.4.14 states that faults shall be applied in turn, and one at a
time. On the other hand I take a look at the practical operation of the unit
being tested. For example one of our units is a floor standing unit that sits
off the ground by about 2 inches. Since there will always
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